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Milton, Hans J/Metric conversion In the QC100 .U57 V598;1980 C.2 NBS-PUB-R 1980 NBS SPECIAL PUBLICATION 598

U.S. DEPARTMENT OF COMMERCE / National Bureau of Standards

METRIC CONVERSION

IN THE CONSTRUCTION

INDUSTRIES — TECHNICAL ISSUES

AND STATUS
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards' was established by an act of Congress on March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology

and facilitate their effective application for public benefit. To this end, the Bureau conducts

research and provides: (1) a basis for the Nation's physical measurement system, (2) scientific and technological services for industry and government, (3) a technical basis for equity in trade, and (4) technical services to promote public safety. The Bureau's technical work is per- formed by the National Measurement Laboratory, the National Engineering Laboratory, and

the Institute for Computer Sciences and Technology.

THE NATIONAL MEASUREMENT LABORATORY provides the national system of

physical and chemical and materials measurement; coordinates the system with measurement

systems of other nations and furnishes essential services leading to accurate and uniform

physical and chemical measurement throughout the Nation's scientific community, industry,

and commerce; conducts materials research leading to improved methods of measurement,

standards, and data on the properties of materials needed by industry, commerce, educational

institutions, and Government; provides advisory and research services to other Government

agencies; develops, produces, and distributes Standard Reference Materials; and provides

calibration services. The Laboratory consists of the following centers:

Absolute Physical Quantities2 — Radiation Research — Thermodynamics and

Molecular Science — Analytical Chemistry — Materials Science. THE NATIONAL ENGINEERING LABORATORY provides technology and technical ser- vices to the public and private sectors to address national needs and to solve national problems; conducts research in engineering and applied science in support of these efforts; builds and maintains competence in the necessary disciplines required to carry out this research and technical service; develops engineering data and measurement capabilities;

provides engineering measurement traceability services; develops test methods and proposes

engineering standards and code changes; develops and proposes new engineering practices;

and develops and improves mechanisms to transfer results of its research to the ultimate user. The Laboratory consists of the following centers:

Applied Mathematics — Electronics and Electrical Engineering- — Mechanical

Engineering and Process Technology 2 — Building Technology — Fire Research —

Consumer Product Technology — Field Methods.

THE INSTITUTE FOR COMPUTER SCIENCES AND TECHNOLOGY conducts

research and provides scientific and technical services to aid Federal agencies in the selection, acquisition, application, and use of computer technology to improve effectiveness and

economy in Government operations in accordance with Public Law 89-306 (40 U.S.C. 759), relevant Executive Orders, and other directives; carries out this mission by managing the Federal Information Processing Standards Program, developing Federal ADP standards

guidelines, and managing Federal participation in ADP voluntary standardization activities; provides scientific and technological advisory services and assistance to Federal agencies; and

provides the technical foundation for computer-related policies of the Federal Government.

The Institute consists of the following centers:

Programming Science and Technology — Computer Systems Engineering.

1 Headquarters and Laboratories at Gaithersburg, M D, unless otherwise noted: mailing address Washington, DC 20234.

: Some divisions within the center are located at Boulder, CO 80303.
National Bureau of Standards

. . .. _ ,

Library, E-OJ Admin. Kdg.

Metric Conversion in the Construction m 4 m

Industries—Technical Issues and Status

Hans J. Milton

Sandra A. Berry

Building Economics and Regulatory Technology

Division

Center for Building Technology

National Engineering Laboratory

National Bureau of Standards

Washington, DC 20234

U.S. DEPARTMENT OF COMMERCE, Philip M. Klutznick, Secretary

Luther H. Hodges, Jr., Deputy Secretary

Jordan J. Baruch, Assistant Secretary for Productivity, Technology and Innovation

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

Issued October 1 980
Library of Congress Catalog Card Number: 80-600173

National Bureau of Standards Special Publication 598

Nat. Bur. Stand. (U.S.), Spec. Publ. 598, 144 pages (Oct. 1980) CODEN: XNBSAV

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1980

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402

Price $5.50

( Add 25 percent for other than U.S. mailing

)
ABSTRACT

This Special Publication was prepared at the request of the Metric

Symposium Planning Committee of the National Institute of Building

Sciences (NIBS). It is intended to provide information on technical

issues and status of metric conversion in the United States construction industries. It will be made available to attendees at the NIBS

Symposium on "Metric Conversion in the Construction Community" to be

held December 2-3, 1980, in Chicago, IL. In addition, it will be available to other affected parties in the construction community.

The report contains information on planning for the metric change,

current metric activities of professional and industry groups, technical

implications in the construction industries, dimensional coordination,

metric building products and services, research issues, and timing. It

is intended to provide assistance for informed decisionmaking relative

to metric conversion for the U.S. construction industries. Also included

in the report is a bibliography of relevant construction industries'

metric technical information.

Keywords: Construction industries; dimensional coordination; metric bibliography; metric conversion timetable; metric decision; metric

product sizes; metric system (SI).

iii
PREFACE

This report has been prepared as an information paper for those

considering issues related to conversion of the building industries to

the metric system of measurement. In particular, it is made available

for those attending the Sympos ium on "Metric Conversion in the Construction Community ," to be held in Chicago, IL, on December 2-3, 1980.

The Symposium is being held under the leadership of the National

Institute of Building Sciences (NIBS) in cooperation with the American

National Metric Council, the United States Metric Board, and the National

Bureau of Standards. The purpose of the Symposium is for the U.S.

construction community:

"To examine opportunities and problems relating to the metric

system of measurement in construction and to consider a procedure

for developing consensus on whether or not the construction

community should convert, and, if so, when."

This report is designed to assist attendees by providing background

information on the status of metric conversion in the United States and

to provide a general understanding of the key aspects of metrication for

the construction community. It was assembled from material provided by

the U.S. construction community and technical data developed by the

Center for Building Technology at the National Bureau of Standards. It

is intended to present pertinent data and an analysis of the principal

issues faced by the construction community . It is recognized that all

of the content will not be of interest to many readers. Therefore the

information has been carefully broken up and headlined so that the table

of contents provides a guide to selective reading.

The report was requested by the NIBS Metric Symposium Planning Committee

,

which is comprised of representatives of the four organizations mentioned

above. The material presented does not represent the formal position of

any organization or individual , except where so indicated.

Special thanks are extended to the principal authors of this report,

Hans J. Milton, FRAIA, Technical Consultant, and Sandra A. Berry of the

National Bureau of Sandards . Mr. Milton's services on metrication and

dimensional coordination v/ere made available by the Australian Government

with the support of the U.S. Department of Housing and Urban Development

.

James G. Gross, Chief

Building Economics and Regulatory

Technology Division

Center for Building Technology

National Engineering Laboratory

National Bureau of Standards

iv
ACKNOWLEDGEMENTS

Constructive comments on an earlier draft of this document were received

from:

David S. Miller

Louis Barbrow

A. Charles Danner

David Gorin

Chairman, Metric Symposium Planning Committee,

National Institute of Building Sciences

National Bureau of Standards

U.S. Metric Board

American National Metric Council

Charlene F. Sizemore Board of Directors, National Institute of

Building Sciences

Thomas C. Tufts Chairman, Construction Industries Coordinating

Committee, American National Metric Council

The authors express appreciation to Ms. Ulesia Gray, Center for Building

Technology Word Processing Center, for her assistance in preparing this

document for publication in a very short time frame.

v
TABLE OF CONTENTS

Page

PART 1 - METRIC CONVERSION DELIBERATIONS AND PLANNING FOR

THE CHANGE

1.1 Historical Background 1

1.2 The U.S. Metric Study and Testimony from the

Construction Industries 2 1.3 Legislative Action, the Establishment of the U.S.

Metric Board 4

1.4 The American National Metric Council, and the Activities

of its Construction Industries Coordinating Committee .... 5 1.5 The GAO Metric Report and Findings Relating to the

Construction Industries 9

1.6 Involvement of the National Institute of Building

Sciences 12

1.7 International Metrication 13

Figure 1.1 ANMC/CICC Draft Metric Conversion Timetable for

the Construction Industries 8

References 13

PART 2 - CURRENT ACTIVITIES IN PROFESSIONAL AND INDUSTRY GROUPS

AND STATE GOVERNMENT POLICIES, METRIC COMMITTEE OR

COORDINATORS, METRIC ACTIONS

2.1 Current Construction-Related Activities 15

2.2 State Construction-Related Metric Activities 36

PART 3 - TECHNICAL IMPLICATIONS OF METRIC CONVERSION IN THE

CONSTRUCTION INDUSTRIES

3. 1 General Aspects 41

3.2 A Comparison of Features of SI and U.S. Customary Units ... 42

3.3 On Units and Numbers 42

3.4 Coherent Units 44

3.5 Decimalization 45

3.6 Metric Practice - or, Rules for the Use of SI 46

3.7 The Practical Application of Measurement 46

3.7.1 Estimation of Magnitudes 46

3.7.2 General Communication of Measurement Information ... 47

3.7.3 Descriptive Information in Written, Typed, or Printed Data 47

3.7.4 Calculations and Computation 47

3.7.5 Practical Measurement in Production and

Construction 47

3.7.6 Quality Control, Testing, and Research 48

3.8 Metric Units for Use by Tradesmen and Site Personnel 48

vi
Page

3.9 Metric Measuring Instruments 50

3.10 Metric Standards 50

3.11 Metric Building Codes 51

3.12 Technical Reference Materials, Handbooks, and Texbooks .... 51

Table 3-1 Concepts in Measurement: Comparison of SI and U.S.

Customary Units 43

Table 3-2 Key Metric Units for Use On-the-Job 49

References 32

PART 4 - METRIC CONVERSION AND DIMENSIONAL COORDINATION IN

BUILDING

4.1 Dimensional Coordination: Background 53

4.2 Metric Dimensional Coordination and the International

Building Module 54

4.3 Metrication and Dimensional Coordination 54

4.4 The Metric Building Module Compared with the Traditional

4-inch Module 55

4.4.1 Metric Modular Dimensions are Directly Visible 56

4.4.2 The Modular Square—A Useful Aid in Calculations ... 56

4.4.3 The Modular Cube 57

4.4.4 An Example of Calculations with Modular Dimensions . 57

4.4.5 Metric Drawing Scales and the Building Module 57

4.4.6 Endorsement of the 100 mm Metric Building Module ... 59

4.5 The Practical Application of Dimensional Coordination in

Building 60

4.6 The Choice of Preferred Dimensions 62

4.7 Issues in Production - Sizes of Modular Building Products

and Components 64

4.8 Construction - The Trade-off Between Design Dimensions

and Product Sizes 65

4.9 Modular Drawing Practice 66

4.10 The Development of Standards for Dimensional Coordination

in Building 66

Figure 4-1 Example of Drawings Scales with Modular Dimensions

Emphasized 58

Figure 4-2 Customary (Foot-Inch) and Metric Construction Steel

Tapes

Figure 4-3 Boundary Controlling Planes

Figure 4-4 Axial Controlling Planes 61

Figure 4-5 Vertical Controlling Dimensions

Figure 4-6 Intermediate Controlling Planes 62

Table 4-1 Comparison of Divisibility 63

Table 4-2 Metric Preferred Size Selection Matrix 65

Table 4-3 Matrix of Modular Design Dimensions vs. Modular

Product Sizes 67

References 68

vii
Page

PART 5 - PROPERTIES AND SIZES OF METRIC BUILDING PRODUCTSPRECEDENT, CHANGES PROPOSED, AND CHANGES MADE

5.1 Metrication and Building Products - Some General

Observations 71

5.2 International Precedent as a Guide 72

5.3 Metrication and Masonry Products 73

5.4 Metrication and Building Lumber 73

5.5 Metrication and Concrete 74

5.5.1 Bulk Materials for Use in Concrete 74

5.5.2 Ready Mixed Concrete 74

5.5.3 Concrete Reinforcing Steel 74

5.5.4 Precast and Manufactured Concrete Products 76

5.5.5 Concrete Design Data and Technical Information 76

5.6 Metrication and Metal Products 76

5.6.1 Structural Steel Sections 76

5.6.2 Fasteners 78

5.6.3 Steel Tubes and Pipes 79

5.6.4 Other Metals - Aluminum, Brass, Copper, Lead,

and Zinc 80

5.7 Glass Products 80

5.8 Panels, Boards, Sheets and Tile 81

5.9 Roofing 82

5.10 Construction Assemblies - Door, Windows, Partitions,

Skylights, etc 83

5.11 Stairways and Built-in Elements 83

5.12 Services Systems: Electrical, Lighting, AirConditioning , Plumbing, etc 84

Figure 5-1 ISO Basic Thread Profile 78

Table 5-1 Principal Dimensional Standards-Glass Products 81

References 84

PART 6 - BUILDING SERVICES AND METRIC CONVERSION

6. 1 Overview 87

6.2 Coherent Design for Energy Utilization and Conservation ... 87

6.3 Electrical and Illumination Engineering 89

6.4 HVAC—Heating, Cooling, Ventilating and Air-Conditioning .. 90

6.5 Hydraulic Design and Plumbing 91

6.6 Acoustical Engineering 93

Figure 6-1 The "joule" (J) as Pivotal Unit for Energy Design ... 88

Reference 93

viii
Page

PART 7 - DEVELOPMENT AND RESEARCH ISSUES IN METRICATION

7.1 Investigation and Research 95

7.2 Precedent and International Implications of Metric

Conversion 95

7.3 Basic Metric Issues 96

7.4 User Studies to Determine Suitable Metric Design

Dimensions 97

7.5 Dimensional Coordination Research 98

7.6 Investigation of Design and Documentation Aspects 99

7.7 Investigation of Building Codes and Standards 100

7.8 Investigations into Building Products and Production

Processes 100

7.9 Investigation of Metrication in Construction and

Maintenance 102

7.10 Adaptation of Materials During A Transitional Period 103

7.11 Research into Legal Implications, Contracts, and

Agreements 103

7.12 Research and Development in Perspective 104

Reference 105

PART 8 - TIMING OF METRIC CONVERSION IN THE CONSTRUCTION

INDUSTRIES—AN ASSESSMENT OF CRITICAL ACTIVITY ITEMS

8.1 Key Features of a Timetable for Conversion 107

8.2 Action Items in the ANMC Construction Industries Metric

Conversion Timetable 108

8.2.1 Publish Metric Practice Guide for Construction

(and revise) 109

8.2.2 Develop Necessary Basic Metric Standards 109

8.2.3 Determine Product Sizes in Metric Units 110

8.2.4 Produce Metric Measuring Equipment 110

8.2.5 Decision to Build Metric Building 110

8.2.6 Award Design Contract (for Metric Design) Ill

8.2.7 Begin Conceptual Design in Metric Ill

8.2.8 Develop and Distribute Metric Product Literature ... Ill

8.2.9 Publish Model Codes in Metric 112

8.2.10 Enact Enabling Legislation (for Metric

Requirements) 112

8.2.11 Conduct Land Transactions in Metric 113

8.2.12 Produce Property Surveys in Metric Units 113

8.2.13 Develop Metric Estimating System 113

8.2.14 Begin Design Development and Engineering in

Metric 113

8.2.15 Estimate and Bid on Metric Documents 114

8.2.16 Award Metric Construction Contract 114

8.2.17 Accept Plans in Metric and Issue Building

Permits 114

ix
Page

8.2.18 Obtain Labor Agreements in Metric 115

8.2.19 Begin Construction of Metric Buildings 115

8.2.20 Deliver Metric Products to Suppliers and Site H5

8.2.21 Complete Metric Construction 115

8.2.22 Occupy and Maintain Metric Buildings 116

8.2.23 Conduct Real Estate Transactions in Metric H6

8.3 Some Comments on the ANMC/CICC Construction Industries

Metric Conversion Timetable 116

8.4 International Precedent in Construction Metrication and

Program Timing 117

8.5 A Model for the Achievement of a Decision on Construction

Metrication 117

8.6 From Timetable to Implementation 119

Figure 8-1 Graphical Illustration of "Phases" in a Change 108

Figure 8-2 A Model for Metrication Decisions in the U.S.

Construction Industries 120

Table 8-1 International Precedent in Metrication in

Construction—Comparison of Program Timing H8

References 121

PART 9 - METRIC BIBLIOGRAPHY

9.1 Government Issuances 123

9.2 Industry and Association Issuances 125

9.3 Handbooks and General Information Issuances 126

9.4 Standards Organizations Issuances 126

9.5 American National Metric Council Issuances 130

PART 10 - APPENDICES

APPENDIX 1 Extracts from NBS SP 345-12 (July 1971), U.S. Metric

Study Interim Report, Testimony of Nationally

Representative Groups 131

APPENDIX 2 Listing of Organizations Contacted for Information

Included in Part 2 141

x
PART 1 - METRIC CONVERSION DELIBERATIONS AND PLANNING FOR THE CHANGE

1 . 1 Historical Background

The metric system of units was proposed at a time when the United

States of America had just put into effect its Constitution, and

George Washington had been named first President. In 1790, France,

Great Britain, and the fledgling United States were all considering

major changes to their systems of weights and measures in order to

reduce diversity and confusion. In each case, uniform measures and a decimal base were proposed, but only in France was a system developed

which has since been adopted by nearly all nations of the world—the

"systeme metrique" or metric system.

Thomas Jefferson, the Secretary of State in 1790, was aware of Talleyrand's proposal to the French National Assembly for a new and radically

different system of units, when he submitted as one of two plans for

consideration an elegant concept of decimally related weights and measures, based on a decimalized foot and a decimalized pound, with a direct relationship to the cubic foot. Although Jefferson's support

for a "decimal" currency had been instrumental in establishing the

decimal concept of measurement as the basis of commerce and accounting,

no action was taken to change weights and measures.

The first serious comparison of English (customary) and French (metric)

measures was made in 1821, in the extensive "Report Upon Weights and

Measures" by John Quincy Adams, stating advantages and disadvantages

of both systems. Adams, however, counseled against any hasty decision

and, thus, the subject remained dormant until the 1860 's, when some major international conferences and the newly formed National Academy

of Sciences took up the subject of an "international" system of

measurement.

The result of new initiatives was that the metric system was authorized

by an Act of Congress passed in 1866 (14 Stat. 339, July 28, 1866),

and thus became permissible for use in any transaction.

In 1875, the United States became one of the original signatory nations

to the Treaty (Convention) of the Meter (20 Stat. 709), which established the General Conference on Weights and Measures (CGPM), the International Committee for Weights and Measures (CIPM), and the International Bureau of Weights and Measures (BIPM). Thus, for over a century,

the United States has actively participated in the development of the

concepts of the metric system and, in recent years, the International

System of Units (SI).

Since 1893, customary units for use in the United States have been

defined in terms of metric units. In addition, all major units for

electricity, magnetism, and illumination now in use in the United

1
States are metric units and, in most instances, pure SI; for example,

watt, volt, ampere, ohm, Siemens [mho], hertz [cps], weber, tesla,

henry, candela, and lumen.

There have been various periods, starting in the 1860's and continuing

into the 1970' s, during which bills have been introduced in Congress

to effect the adoption or wider use of the metric system. Hearings

were held on many occasions, under the auspices of Senate or House of

Representatives' committees [1]*.

Since the formation of the Congressional Committee on Science and

Technology in 1959, which by House rule has been charged with the general oversight of the "standardization of weights and measures and the

metric system, " bills have been introduced that year and every year

following to effect wider use of the metric system in the United States

or to provide for surveys and studies to weigh the advisability of doing

so.

In 1960, the United States was a signatory to the 11th General

Conference on Weights and Measures, which formally gave the title

"International System of Units" to the rationalized and coherent ver- sion of the metric system, for which the abbreviation "SI" is used in

all languages. With this action, the change became an "international"

issue, reflecting the international participation in the development

of SI. Following a decision in 1965 by British industry to change to

SI, based on a voluntary conversion, one by one all other Englishspeaking nations decided to replace their customary measurement systems

with the International System of Units. Of the major nations, the decision by South Africa was followed by Australia, New Zealand, and Canada,

so that by the mid-1970 's only the United States had not reached a decision.

1 . 2 The U.S. Metric Study and Testimony from the Construction

Industries

On August 9, 1968, the President signed Public Law 90-472 (82 Stat.

693), "An Act to authorize the Secretary of Commerce to make a study to

determine the advantages and disadvantages of increased use of the

metric system in the United States," also referred to as the Metric

Study Act of 1968. The Act specified that the Secretary of Commerce

should submit to Congress, within 3 years, a full and complete report

of the findings, together with such recommendations as considered to

be appropriate and in the best interests of the United States. The

"U.S. Metric Study" was conducted by the National Bureau of Standards,

and has been reported in a 12-volume U.S. Metric Study Interim Report

(NBS SP 345-1 to SP 345-12) [2], as well as a Report to the Congress (NBS

SP 345 - July 1971), entitled "A Metric America - A Decision Whose Time

Has Come" [3]. The report concluded that the United States should

* Numbers in brackets refer to references at end of each Part.

2
change to the metric system through a coordinated national program,

and provided a number of more detailed recommendations, for example:

° that the Congress assign the responsibility for guiding the change,

and anticipating the kinds of special problems described in the

report, to a central coordinating body responsive to all sectors of

society;

° that within this guiding framework, detailed plans and timetables

be worked out by the sectors themselves;

° that early priority be given to educating every American schoolchild

and the public at large to think in metric terms;

0 that immediate steps be taken by the Congress to foster U.S.

participation in international standards activities;

° that in order to encourage efficiency and minimize the overall costs

to society, the general rule should be that any changeover costs

shall "lie where they fall;"

° that the Congress, after deciding on a plan for the Nation, establish

a target date 10 years ahead, by which time the United States will

have become predominantly, though not exclusively, metric; and,

° that there be a firm government commitment to this goal.

As part of the U.S. Metric Study, the construction industries were

asked to respond on their feelings about the projected change to metric

measurement. This was accomplished by means of questionnaires and

interviews, as well as by means of a two-day Construction Industry Conference, held at the National Bureau of Standards, U.S. Department of

Commerce, on October 5-6, 1970.

The responses from the "contract construction" sector of nonmanufacturing businesses are detailed in U.S. Metric Study Interim Report

No. 5 - Nonmanufacturing businesses (NBS SP 345-5). The following estimates were made by construction respondents as to a reasonable time

period for the change:

3
Percentage Cumulative Percentage

11 - 15 years

16 - 20 years

Over 20 years

Never

Immediately

1-2 years 3-5 years

6-10 years

0%

6%

17%

45%

6%

8%

4%

3%

0%

6%

23%

68%

74%

82%

86%

89%

No answer or don't know 11%

100%

The response indicates that a majority of the respondents who chose a time frame regarded a 6-to-10 year period as reasonable, namely 45/89

or 50.6 percent. If the responses favoring a shorter time frame ai'e

added, 68/89, or 76.4 percent, opted for a time frame within 10 years.

However, when asked about the current attitude of your company toward

increased metric usage in your operations 3 37 percent of the construction companies indicated that they were mildly or strongly against

against metrication, while 24 percent indicated that they were for

metrication. The remainder—39 percent—were either neutral or noncommittal (no answer, don't know). Fifty-seven percent of construction

representatives indicated that they believed increased metric usage was

in the best interest of the United States.

Additional testimony from the construction sector was obtained with the

assistance of the Construction Affairs Committee of the U.S. Chamber of

Commerce. The testimony from 26 major construction related groups is

summarized in U.S. Metric Study Interim Report No. 12 - Testimony of

Nationally Representative Groups, pages 76 - 86. The summaries of

findings have been reproduced as Appendix 1, as are the inputs from

individual groups that gave testimony, including the construction

industry's unions, whose testimony were presented at a separate National

Metric Study Conference on Labor.

1 . 3 Legislative Action, the Establishment of the U.S. Metric Board

Following the U.S. Metric Study Report, legislation was forwarded to

Congress by the Administration for a voluntary ten year plan to convert the nation to the metric system [92nd Congress]. However, no action was taken.

A number of bills were introduced in the 93rd Congress, with hearings

held on them en bloc in March and May 1973, followed by the reportingout of a metric bill by the Subcommittee on Science, Research, and

Technology, which was amended in the full Committee in October 1973.

On May 7, 1974, this bill was brought to the floor under a suspension

4
of rules which requires a two-thirds vote, but it was not acted upon

favorably.

In the 94th Congress, many bills were introduced in 1975, culminating

in the reporting-out of H.R. 8674, which was subsequently considered

and passed by the House on September 5, 1975; considered and passed by

the Senate, but amended, in lieu of Senate bill S. 100, on December 8,

1975; concurred on the Senate amendment by the House on December 11,

1975; and signed into Law by President Ford on December 23, 1975, as Public Law 94-168, cited as the "Metric Conversion Act of 1975" [4].

The purpose of the Act is stated as "To declare a national policy of

coordinating the increasing use of the metric system in the United

States, and to establish a United States Metric Board to coordinate the

voluntary conversion to the metric system. " The Act does not specify

a timetable for conversion, nor does it speak about the sole or predominant use of the metric system; rather, it mentions that "this Nation

is the only industrially developed nation which has not established a national policy of committing itself and taking steps to facilitate

conversion to the metric system, " and that "it is therefore declared

that the policy of the United States shall be to coordinate and plan

the increasing use of the metric system in the United States and to

establish a United States Metric Board to coordinate the voluntary

conversion to the metric system."

The remainder of the Act deals with the establishment, structure,

functions, and duties of the U.S. Metric Board, which, according to the

Act, consists of a Chairman and 16 members appointed by the President

by and with the advice and consent of the Senate. It is significant

that Section 5. (b)(2)(H) specifies one of the members "to be selected

from lists of qualified individuals representative of the construction

industry." This gives the building and construction industries a direct

voice in the deliberations of the U.S. Metric Board.

The original slate of nominees as Board members was rescinded after the

change of Administration in 1976, and the official appointment of the

U.S. Metric Board took place after the Senate had confirmed the first 13

nominees on March 21, and the other four nominees on June 20, 1978. The

Chairman of the U.S. Metric Board is Dr. Louis F. Polk, of Dayton, OH,

and the Vice-Chairman is Adrian Weaver of Stamford, CT. The member representing the construction industry is Francis R. Dugan, of Cincinnati, OH.

The administrative offices of the U.S. Metric Board are located at

1815 N. Lynn Street, Arlington, VA 22209; Phone (703) 235-1933.

1 . 4 The American National Metric Council, and the Activities of its

Construction Industries Coordinating Committee

As a result of increased metric discussion in the United States following

the Report of the U.S. Metric Study in 1971, the American National Metric

Council (ANMC) was formed in 1973. It was formed by private sector

5
initiative and under the sponsorship of the American National Standards

Institute (ANSI), as a nonprofit organization to assist all segments of

the U.S. economy in the planning, coordination, and implementation of a voluntary change to the metric system of measurement.

In January 1974, representatives from the main segments of the construction industries met as a Steering Group for Building and Construction

in ANMC, to establish strategies and policies for metric conversion

activities. This Steering Group is now known as the Construction Industries Coordinating Committee (CICC). ^ Subsequently, a number of Sector

Committees and Subsectors were formed to represent specific segments of

the construction and allied industries and services. For the purposes

of ANMC, these planning groups were given the following numeric codes:

3.00 CONSTRUCTION INDUSTRIES COORDINATING COMMITTEE [1974]

3.01 Design Sector [formed 1976]

Subsectors: Engineering

Architecture

3.02 Construction Codes and Standards Sector [formed 1975]

Subsectors: Building Codes

Electrical Codes

Plumbing Codes

Mechanical Codes

Elevator Codes

Fire Prevention Codes

State Implementation and Training

Canadian Code Liaison

3.03 Construction Products Manufacturers Sector [formed 1975]

Subsectors: Basic Structure

Exterior/Interior Finish and Insulation

Openings

Roofing

Mechanical/Electrical

Cabinets and Case Goods

Hardware

3.04 Contractor Sector

3.05 Information Sector

The reference to Coordinating Committee in this text preceded the

May 12, 1980, decision by the ANMC Board of Directors designating

Coordinating Committees as Coordinating Groups.

6
3.06 Real Estate Sector [formed 1975]

3.07 Users Sector (Building Clients)

3.08 Surveying and Mapping Sector [formed 1975]

Also: Labor Liaison Committee (formerly Sector 3.05)

Participation in ANMC's planning activities for the construction industries has included more than 300 individuals, representing more than 150

industry associations or organizations.

During 6 years of meetings, the CICC and its various sector committees

developed a comprehensive conversion plan for the U.S. construction

industries. By March 1978, CICC had identified all key metric activities in all sectors then in existence and had related these activities

in a series of logical networks showing interdependencies and sequences.

These activity sequence charts for each sector and for the industry as a whole were shown publicly at the 4th Annual ANMC Conference in Atlanta,

GA, in April 1978. During 1978, likely durations for the various activities were assessed, and in April 1979, at the 5th Annual ANMC Conference

in Washington, D.C., a draft Construction Industries Metric Conversion

Schedule was unveiled. This draft schedule provided the overall sector

management program for metric conversion. In September 1979, the CICC

and all its sector committees met to consider an expanded set of action

schedules—or timetables—for each sector and the construction industry

at large. These documents were subjected to the review by all individuals and groups associated with ANMC/CICC. In December 1979, the

CICC met in Washington, D.C. , and resolved to accept the timetable as a feasible basis for a voluntary change to metric, and decided to submit

it for general approval and a commitment to change. On April 4, 1980, as a prelude to the construction sessions at the 6th Annual ANMC Conference

in San Francisco, CA, the Metric Reporter [5] featured the ANMC/CICC

Construction Industries Metric Conversion Timetable (figure 1-1). The

Reporter also contained a ballot to permit individuals and/or organizations to express their feelings on the timetable.

The activities of the Construction Industries Coordinating Committee of

ANMC, in attempting to develop a voluntary plan for metric conversion

in the construction industries, have been detailed in the ANMC Construction Industries Coordinating Committee special publication (May 1980),

"Metric Conversion in the Construction Industries. .. Planning, Coordination and Timing" [6].

This Timetable has not been submitted to the U.S. Metric Board for

examination and general review in line with the procedures outlined in

Section 6.(2) and 6.(3) of the Metric Conversion Act of 1975. These

procedures state,

7
Figure 1-1: ANMC/CICC Draft Metric Conversion Timetable for the

Construction Industries

AMERICAN NATIONAL METRIC COUNCIL

CONSTRUCTION INDUSTRIES COORDINATING COMMITTEE

CONSTRUCTION INDUSTRIES METRIC CONVERSION TIMETABLE

3 00 CONSTRUCTION INDUSTRIES COORDINATING COMMITTEE

Action Item Publish Metric Practice Guide for Construction (and Revisel Develop Necessary Basic Metric Standards

Determine Product Sizes in Metric

Units

Decision to Build Metric Building

Award Design Contract Develop and Distribute Metric Product Literature Produce Metric Measuring Equipment

Begin Conceptual Design In Metric

Publish Model Codes in Metric

Develop Metric Estimating System

Enact Enabling Legislation

Conduct Land Transactions in Metric

Produce Property Surveys in Metric Begin Design Development and

Engineering in Me'ric

Estimate and Bid on Metric Documents

Award Metric Construction Contract Accept Plans in Metric and Issue Building Permits

Obtain Labor Agreements in Metric Begin Construction of Metric

Buildings

Deliver Metric Products to Suppliers and Site Complete Metric Construction

Occupy and Maintain Metric Buildings Conduct Real Estate Transactions

in Metric

Schedule Code Preliminary Metric Conversion Activity More and more organizations become involved

Intensive Metric Conversion Activity Most of the required changes are made Decreasing Metric Conversion Activity Any remaining changes are made Normal Metric Activity

Metric measurement has become predominant

Sector Number Code 3.01 Design 3 02 Codes and Standards 3.03 Construction Products 3.04 Contractors 3.05 Labor Liaison 3.06 Real Estate 3.07 Users/Building Clients 3.08 Surveying and Mapping 3.09 Information

8
"In carrying out this program, the Board shall

(2) provide for appropriate procedures whereby various groups,

under the auspices of the Board, may formulate, and recommend or suggest, to the Board specific programs for coordinating conversion

in each industry and segment thereof and specific dimensions and

configurations in the metric system and in other measurements for

general use. Such programs, dimensions, and configurations shall

be consistent with (a) the needs, interests, and capabilities of

manufacturers (large and small), suppliers, labor, consumers, educators, and other interested groups, and (b) the national interest;

(3) publicize, in an appropriate manner, proposed programs and

provide an opportunity for interested groups or individuals to

submit comments on such programs. At the request of interested

parties, the Board, in its discretion, may hold hearings with

regard to such programs. Such comments and hearings may be considered by the Board;"

The 23 Action Items of the Construction Industries Metric Conversion

Timetable are analyzed and expanded in Part 8 of this publication.

1 . 5 The GAP Metric Report and Findings Relating to the Construction

Industries

Following the passage of the Metric Conversion Act of 1975, concern was voiced by pro-metric as well as anti-metric groups about the implications of the Act. The General Accounting Office (GAO) undertook a study

and reported to Congress on the implications of adoption of the metric

system. It assigned a task force of GAO staff members to conduct a lengthy inquiry, involving both questionnaires and personal interviews,

as well as analysis of available studies and documents.

On October 20, 1978, the Comptroller General released GAO Report CED-78-

128, entitled "Getting a Better Understanding of the Metric SystemImplications If Adopted By the United States." The 740-page Report to

Congress and its Executive Summary [7] have not resolved the metric con- troversy in the United States, and contain no direct recommendations to

Congress. However, on page 30-23, the Report states, "We believe, on

the basis of the conversion lessons learned from the foreign countries

experience, that if the United States is to be predominantly metric,

the Congress should amend the Metric Conversion Act of 1975 to make it

the national policy to convert to the metric system as the predominant

system of weights and measures within a certain number of years. Also,

the U.S. Metric Board should accept lessons learned in other countries."

The report emphasizes potential problems, concerns, and anticipated

costs of the change and is, therefore, a useful guide to those areas which require additional research and investigation. In relying on "estimates," the report acknowledges that accurate assessments of either

costs or benefits are not possible, but that the costs of the change

would be substantial. The Report summarizes on page 31-27, "It would

seem that as a minimum before voluntarily deciding to convert, there

9
should be a clear understanding of the policy, knowledge of the costs

and benefits involved, an assessment of the impact on the sector involved and any related sector, and a determination of the impact on con- sumers." Chapter 11 of the report, "Automotive Industry Provides an Impetus," deals largely with costs and benefits, and clearly indicates

that initial cost estimates can be largely misleading and vastly overstated. In this industry, it is believed that the coupling of metrication with the introduction of new products or normal replacement cycles

will result in benefits which will ultimately outweigh the costs.

The largest chapter in the GAO Report, Chapter 16, deals with the

building and construction industries. The 55-page chapter, entitled "A

Dilemma for the Building and Construction Industry," states some of the reasons why conversion is progressing at a slow rate. It also finds the

industry, generally, is passive towards it, even though much of the

industry considers conversion to be inevitable and beneficial for the

United States as a whole.

"The apparent reasons for the lack of activity (at the time of the

study—1976-1978) are that (1) the industry presently has no compelling

reasons to convert, (2) the industry is uncertain of the national policy

and Federal commitment to conversion, (3) parts of the industry are con- cerned about the costs and not certain of the benefits, and (4) it is

difficult for individual firms or segments of the industry to act

alone—the industry is too diversified, and no firm is large enough to

lead. Metrication of the building and construction industry probably

would not occur in the near future unless it is mandated or the Federal

Government plays a greater role in bringing it about."

The chapter itself contains a great deal of useful information, based

on the result of 285 usable replies to a construction industry questionnaire, sent to 394 industry associations, as well as quotes from

interviews conducted with various industry spokesmen. In presenting

responses to various questions, the report uses a breakdown:

1. Construction Industry Associations (285)

a. Designers

b. Contractors

c. Labor

d. Manufacturers

e. Distributors

f. Codes and Standards

g. Real Estate

2. Small Construction Firms (67) from Survey of 1000 Small Businesses.

The categories of industry association, except for distributors, reflect

the sectors adopted by the American National Metric Council.

The GAO Study also asked a number of questions on timing of metric con- version in the construction industry, in Section F. of the Questionnaire

(shown on page 16-55 of the Report).

10
Question 20. asked: "If the United States converts to the metric system,

approximately what would be the shortest time frame for the majority of

your members to convert?", and Question 21. asked: "If conversion is

not made mandatory, what would be the optimum amount of time your members

would need to convert?"

The GAO Task Force chose different time spans from those used in the

U.S. Metric Study, having only two options rather than four options for

the first 10 year period, and four options rather than two options for

periods exceeding 20 years. Thus, the median in the eight GAO options

falls at 20 years, compared with a median of 10 years in the eight U.S.

Metric Study options.

Despite this difference in approach, the findings on timing were not

dissimilar as indicated in the text on "conversion target dates" (pages

16-45 and 16-46), which is quoted in full below.

"[A] time frame is needed for the industry to properly plan and coordinate. Architects would know when metric products are available, and

manufacturers would know when to produce metric products.

"Many factors should be considered in establishing a time frame. For

example, some may want a time frame as short as practicable because of

the dual inventories problem. Others may believe a longer time frame

is necessary. The guiding principle should be to maximize benefits and

minimize costs. More than one target date may be established for the

industry with the time frame of one segment differing from, but coordinated with, that of others.

"About 90 percent of the associations and 77 percent of the small

construction firms said that they could convert in 10 years or less.

Sixty-three percent of the associations and 62 percent of the small

construction firms thought that 10 years or less would be the optimum

time frame for conversion; i.e., conversion could be most favorably

implemented in 10 years or less."

Minimum Conversion Time Frame

Time Period Associations Cumulative Small Construction Cumulative

Firms

Under 5 years 37% 37% 42% 42%

5-10 years 54% 91% 35% 7_7_% 11-15 years 5% 96% 12% 89%

16 - 20 years 2% 98% 89%

21 years + 1% 99% 3% 92%

Never 1% 100% 7% 99%

11
Optimum Conversion Time Frame (Conversion not made mandatory)

Time Period Associations Cumulative Small Construction Cumulative

Firms

Under 5 years 21% 21% 31% 31%

5-10 years 63% 63% 31% 62%

11 - 15 years 14% 77% 10% 72%

16 - 20 years 7% 84% 5% 77%

21 years + 5% 89% 3% 80%

Never 11% 100% 19% 99%

1 . 6 Involvement of the National Institute of Building Sciences

With the development of the draft of a Construction Industries Metric

Conversion Timetable, representatives of construction industry associations working under the auspices of ANMC/CICC determined that a wider

dissemination of the information and planning data should be made to all

segments of the industry, to decide whether metric conversion was feasible, and, if so, whether it should be undertaken by means of a voluntary,

private-sector led conversion program based on the ANMC/CICC timetable.

A cornerstone of the planning was the decision by the Construction

Industries Coordinating Committee of ANMC that industry leaders should

be acquainted with metric conversion issues, opportunities and concerns,

as well as the metric conversion plan and schedule developed by ANMC/

CICC. In September 1979, the National Institute of Building Sciences

(NIBS) —as the major forum for the construction industry—was invited

to be a sponsor of a national conference on metric issues and the ANMC/

CICC Timetable, together with the American National Metric Council, the

U.S. Metric Board (USMB), and the National Bureau of Standards (NBS).

Subsequently, NIBS decided that it should organize such a conference on

a nonadvocate basis, with the assistance and cooperation of ANMC, USMB,

and NBS. In that way, both pro-metric and anti-metric views could be

presented in a construction-oriented context. The symposium on "Metric

Conversion in the Building Industry" will be held in Chicago, Illinois,

on December 2-3, 1980.

In February 1980, NIBS mailed a questionnaire on "Metric Conversion of

the Building Industry" to all its members, to ascertain interest in

attendance, and some feedback on: (1) aspects of metrication that have

been researched; (2) the willingness of individuals to present a paper

and the subject(s) for such a paper; and, (3) concerns about aspects of

metrication. From responses it is clear that dimensional (modular)

coordination and derived preferred sizes are regarded as the principal

issues for the construction community.

12
1.7 International Metrication

Close contacts are being maintained by the ANMC , USMB, and standardsgenerating organizations with the Canadian building design, production,

and construction industries to monitor their experiences during the

transition to metric (SI) units, and to obtain information on any action

that may assist the United States in making decisions on metric conversion. The Canadian building industry planned for an M-Day of January 1,

1978, and an M-Year of 1978, during which the actual changes in production and construction would be initiated, followed by a transition period

of a few years and predominantly metric new construction by December 31,

1980.

In addition, information on approaches and metric practices developed

during the changes in the construction industries of Britain, Australia,

and New Zealand has been available to guide the United States in terms

of technical precedent. But, rather than just following the patterns

of other countries, analysis of precedent will indicate trends and

make it possible for the United States to make decisions appropriate

to its own needs and industrial patterns.

REFERENCES

1. Report to Accompany H.R. 8674; Report No. 94-369, 94th Congress,

Committee on Science and Technology; July 17, 1975; pp. 11-14.

2. U.S. Metric Study Interim Reports; NBS Special Publications,

National Bureau of Standards, Washington, D.C., 20234:

SP 345- 1 - Huntoon, R.D. et al., "International Standards;"

150 pages.

SP 345- 2 - Clark, R.E., and Tascher, J.M., "Federal Government:

Civilian Agencies;" July 1971; 328 pages.

SP 345- 3 - Hatos, S.L., "Commercial Weights and Measures;"

July 1971; 11 pages.

SP 345- 4 - Barbrow, L.E., Coordinator, "The Manufacturing Industry;

July 1971; 172 pages.

SP 345- 5 - Cornog, J.R., and Bunten, E.D., "Nonmanufacturing

Businesses;" July 1971; 200 pages.

SP 345- 6 - Robinson, B.D., "Education;" July 1971; 216 pages.

SP 345- 7 - Survey Research Center, et al. , Rothrock B.D, Editor,

"The Consumer;" July 1971; 152 pages.

SP 345- 8 - Gordon, G.F. , "International Trade;" July 1971; 188

pages.

SP 345- 9 - Barbrow, L.E., Coordinator, "Department of Defense;"

July 1971; 132 pages.

13
SP 345-10 - Treat, C.F., "'A History of the Metric System Controversy

in the United States;" August 1971; 312 pages.

SP 345-11 - Stiehler, R.D., "Engineering Standards;" July 1971; 264

pages.

SP 345-12 - Odom, J.V., Editor, "Testimony of Nationally Representative Groups;" July 1971; 180 pages.

3. Report to The Congress, "A Metric America - A Decision Whose Time

Has Come;" Daniel V. de Simone; Special Publication 345; National

Bureau of Standards, Washington, D.C.; July 1971; 170 pages.

4. Public Law 94-168, "Metric Conversion Act of 1975;" 94th Congress,

H.R. 8674; available from U.S. Metric Board, 1815 N. Lynn Street,

Arlington, VA, 22209.

5. Metric Reporter, April 4, 1980, pages 5-8; American National Metric

Council, 1625 Massachusetts Avenue, N.W., Washington D.C. , 20036.

6. "Metric Conversion in the Construction Industries . . . Planning,

Coordination and Timing," American National Metric Council, 1625

Massachusetts Avenue, N.W. , Washington, D.C, 20036; May 1980;

56 pages.

7. Report to the Congress by the Comptroller General of the United

States, "Getting a Better Understanding of the Metric System

Implications If Adopted by the United States," CED-78-128; U.S.

General Accounting Office, Distribution Section, 441 G Street, N.W.,

Washington, D.C, 20548; October 20, 1978; 740 pages.

Executive Summary, CED-78-128A; U.S. General Accounting Office,

Distribution Section, 441 G Street, N.W. , Washington, D.C, 20548;

October 20, 1978; 87 pages.

14
PART 2 - CURRENT ACTIVITIES IN PROFESSIONAL AND INDUSTRY GROUPS AND

STATE GOVERNMENT POLICIES, METRIC COMMITTEES OR COORDINATORS,

METRIC ACTIONS

2 . 1 Current Construction Related Metric Activities

In the spring of 1980, the NBS Center for Building Technology sent a letter to 128 professional societies, trade associations, and individual

companies requesting metric conversion information. This section of

the document is comprised of excerpts from responses to this letter.

For the most part, those contacted are organizations which at sometime

had representatives at a meeting of one of the Sectors comprising the

Construction Industries Coordinating Committee of the American National

Metric Council. In a few instances, organizations were contacted

because they are well known in the construction community.

Following is a breakdown of inquiries sent and responses received

separated into categories similar to the Sector divisions of the Construction Industries Coordinating Committee of the American National

Metric Council.

Construction Related National Associations

Number of Number of

Sector Inquiries Sent Responses

Design 13 9 Codes and Standards 19 10

Product Manufacturers 35 15

Contractors 9 3 Information 0 0

Real Estate 6 0

Surveying and Mapping 3 2 Labor Liasion 4 0

93 39

Construction Related Individual Companies

Number of Number of

Sector Inquiries Sent Responses

All Sectors 35 12

There were a total of 51 responses to the inquiry. Following is a summary of the information contained in these responses from Construction Related National Associations and Individual Companies combined:

15
Sector

Has Published Metric Has Metric Has Metric Has Metric

Information Policy Coordinator Committee

Design UUj 0J

0J z Z Codes and Standards (10) c.D 9 Z rroduct \nlgs) \£oj 1 0 Q 1 u

l ^ 1

J

Contractors (3) 0 1 3 1 Information (0) 0 0 0 0

Real Estate (0) 0 0 0 0

Users \(j ) u u U u Surveying and

Mapping ( 2

)

9 9 1 i Labor Liaison (0) 0 0 0 0

21 17 20 19

The following organizations responded to the inquiry:

Aluminum Association, The

American Association of Cost Engineers

American Concrete Institute

American Congress on Surveying and Mapping

American Hospital Association

American Institute of Architects

American Insurance Association

American Iron and Steel Institute

American Plywood Association

American Society for Testing and Materials

American Society of Heating, Refrigerating and Air-Conditioning

Engineers

American Society of Mechanical Engineers

American Society of Photogrammetry

American Society of Plumbing Engineers

American Standard/U. S. Plumbing Products

Associated General Contractors of America

Association of Wall and Ceiling Industries - International

Bethlehem Steel Corporation

Bliss Steel Products Company

Brick Institute of America

Building Officials and Code Administrators International, Inc.

Business and Institutional Furniture Manufacturers Association

Carrier International Corporation

Concrete Reinforcing Steel Institute

Copper Development Association

Gypsum Association

Halstead and Mitchell-Division of Halstead Industries

Illuminating Engineering Society of North America

Interior Design Educators Council

International Association of Plumbing and Mechanical Officials

International Conference of Building Officials

16
Manufactured Housing Institute

Mechanical Contractors Association of America, Inc.

Mobil Research and Development Corporation

Monsanto Company

National Association of Home Builders

National Concrete Masonry Association

National Electrical Contractors Association

National Forest Products Association

National Society of Professional Engineers

Portland Cement Association

Prestressed Concrete Institute

Quaker-Maid - A Tappan Division

Red Cedar Shingle and Handsplit Shake Bureau

Society of American Registered Architects

Southern Building Code Congress International, Inc.

Tishman Research Corporation

Underwriters' Laboratories, Inc.

Union Carbide Corporation

United States Gypsum Company

Weyerhaeuser Company

A summary of each of the above organization's response follows in

alphabetical order. Those organizations responding that have no metric

conversion activity are included as well.

The Aluminum Association . The Aluminum industry, through committees of

the Aluminum Association, has been preparing for metric conversion for

over 9 years. The Association serves as secretariat to American National

Standards Committee H35 , which has published metric standards. The Association observes preferred metric sizes for metals established under

American National Standards Committees B32.3 and B32.4. The Association

has a metric committee which is chaired by Philip C. Althen, ALCOA,

and J. W. Barr of The Aluminum Association is responsible for association

metric activities. It published a "hard" metric version of its standards

manual in 1978.

American Association of Cost Engineers . This association has a publication guide to authors which requires both customary and metric notation

on all units in publications. Papers submitted containing SI units do

not require English equivalents; however, the reverse is required. The

Association expects to drop the use of English units altogether after a couple of years and publish exclusively in SI.

American Concrete Institute . The American Concrete Institute (ACI) has

a 13-member Metrication Committee, chaired by Clarkson Pinkham, of S.B.

Barnes and Associates, Los Angeles, CA. The mission of the Committee

is: "To remain abreast of developments related to metric conversion

and dimensional coordination, to evaluate the impact of these developments on the Institute and its membership, to assist the Board in

coordinating the various Institute activities related to metrication

17
and to recommend to the Board policies and objectives with regard to

metrication and dimensional coordination."

In addition, the ACI Board of Directors has adopted the following metric

policy:

"It is the policy of the American Concrete Institute to support

actively the use of the International System of Units (SI). Metric

Conversion offers a unique opportunity to achieve greater dimensional coordination. The American Concrete Institute actively supports the development and implementation of a rational system of

standard dimensions as a part of the processes of conversion to SI."

American Congress on Surveying and Mapping . This organization provided

quite a lengthly response to the inquiry. It has been very active in

the metric area and, therefore, its entire response is included.

Members of the surveying and mapping profession have discussed and

written about the conversion to SI for many years. Since the signing of

the Metric Bill by President Ford, the American Congress on Surveying

and Mapping (ACSM), under the leadership of Dr. Charles A. Whitten, and

in conjunction with the American National Metric Council, has prepared

a guide entitled, "Metric Practice Guide for Surveying & Mapping."

Both ACSM and ASCE have affirmatively declared it a policy to assist in

the orderly transition to the metric system. The ACSM charge for 1980

is

"Metric Committee (presidential)"

The Metric Committee establishes and maintains liaison with appropriate federal agencies concerned with the adoption of the metric

standard in the United States. Through ACSM periodical publications

and such monographs as the "Metric Practice Guide," the committee

provides up-to-date information on a continuing basis for the ACSM

membership on the status of the application of the metric system in

the United States as it affects various aspects of surveying and

cartography. The committee continues to serve as the secretariat

for the surveying and mapping sector of the American National Metric

Council, supporting the views and interests of our professions

before the ANMC , the U.S. Metric Board, and other agencies. The

committee will, in cooperation with other societies and agencies,

recommend a schedule of adoption of linear metric measurements by

survey personnel and offices. Methods and degree of use should be

considered.

In March 1980 at the annual convention of the ACSM and the American

Society of Photogrammetry (ASP) in St. Louis, the following resolution

was presented and adopted by the membership. It is currently being

reviewed by the Board of Directors.

18
"Whereas, The President of the United States has signed the Metric

Conversion Act (PL 94-168) in 1975; and

Whereas, The American National Metric Council has supported a voluntary conversion target date for 1985; and

Whereas, U.S. government agencies are in the process of conversion;

and

Whereas, The U.S. Metric Board has provided leadership in coordinaing conversion; and

Whereas, A smooth transition to the metric system as it pertains

to land survey matters is in the best interest of the American

people; Therefore, be it

Resolved, That American land surveyors have an obligation to prepare

for conversion now;

Resolved, That land surveyors in private practice and in public

service are urged to take the initiative in their daily performance

of duties;

Resolved, That all new land survey plats and plans be prepared at a ratio scale whenever possible;

Resolved, That a dual bar scale in meters and in feet be shown on all land survey plats and plans;

Resolved, That, wherever possible, all areas be shown in or ha

and that the equivalent in acres be added in parentheses on land

survey plats and plans;

Resolved, That, wherever possible, all field surveys be executed

with metric equipment and be recorded in metric units:

Resolved, That land surveyors join their state societies in assisting the public, their clients, attorneys, realtors, architects, and

engineers in all relevant metric conversion matters."

In addition, the resolution was adopted by the New England Section of

ACSM at its meeting in May 1980.

The Florida Society of Professional Land Surveyors is represented on

the Florida Metric Council. In 1978 it published the Florida Metric

Plan.

19
The U.S. Geological Survey has commenced publishing topographical

quadrangle maps at ratio scales showing metric contour elevations in

cooperation with several states.

The National Geodetic Survey of NOAA is currently advising and assisting

state surveyors' societies in adapting legalized state plan coordinate

systems to SI.

Many surveyors in private practice have begun to include meter/feet bar

scales on their drawings. Also, the addition of square meters to the

customary square footage and acreage of land is being added to land survey plans. A few surveyors have begun to show distances of boundaries

in meters. Generally, it has been agreed that land title records be

converted only when a new survey or subdivision takes place.

The response concluded:

"The problem with surveying is that it is dependent upon the

cooperation and consent of the legal profession, the real estate

industry, architects, engineering and construction clients. As

long as it is a voluntary method, it may become a matter of individual preference and may lead to undesirable disputes between

various users of surveyors' plans."

The organization has a metric committee and Mr. Gunther Gruelich is its

Chairman.

American Hospital Association . This association has monitored two aspects

of metric conversion: (1) the impact it would have on any management or operational concern in hospitals, and (2) the effects it would have on

the health facility. Although it has issued no material or publications

to its members, the American Hospital Association is highly interested

in other organizations that have developed useful guidance in the metric

conversion subject area.

The American Institute of Architects . The American Institute of Architects (AIA) metric coordinator is Robert T. Packard, of Washington, D.C.

Following is the AIA policy on metric conversion:

"Policy Statement That the Board of Directors of the American

Institute of Architects supports the Metric Conversion Act of

1975 (P.L. 94-168) as related to the construction industry, and

further urges that the metric system be adopted as the national

standard of weights and measures in the United States of America."

An "AIA Metric Building and Construction Guide" has been developed and

was published by Wiley Interscience , Inc. A metric sounding board of AIA

members interested in the conversion process has been established.

These members are kept informed of metric events, and individuals are asked to attend and report on metric meetings affecting the construction

industry.

20
The Board of Directors at its May 28-30, 1980, meeting adopted the

following policy:

"The Board of Directors approves the ANMC/CICC Metric Conversion

Timetable for the U.S. Construction Industries establishing

January 1, 1985 as the date on which metric construction may begin

in the United States."

American Insurance Association . The American Insurance Association has

no metric publications; however, staff members have attended meetings

of the American National Metric Council and it does have an interest in

metric conversion.

American Iron and Steel Institute . The American Iron and Steel Institute

(AISI) has had a Metrication Planning Committee for some years. It has

been concerned primarily with metric issues such as proper use of units,

questions of precision and training methods, which arise in processing

steel ordered in the metric system through the plants—from order processing to shipment. It has published a Metric Practice Guide.

American Plywood Association . The American Plywood Association has a metric advisory committee which has recommended the metric panel size

of 1200 x 2400 mm for sheathing grades of plywood. The committee voted

to recommend panel thickness designation at the lower end of tolerances —no minus tolerances. Metric equivalencies for plywood sizing were also adopted. Work is underway on metric thicknesses for sanded

panels.

American Society for Testing and Materials . The American Society for

Testing and Materials (ASTM) has a Metric Practice Committee—E43—whose

proposed scope is:

The committee shall develop and maintain standards relating to the

modern metric system (the International System of Units, SI) and

its use. To facilitate carrying out this function is shall maintain a continuing surveillance of activity and practice in metric

acceptance and use. The committee will provide advice and coordination on metric practice in standards and other publications for

other ASTM technical committees. This committee will coordinate

its work with that of other organizations having mutual interests.

The Committee Chairman is John F. Corey, Shelby, NC. The ASTM has published several standards. These are included in Part 9 of this report.

The basic ASTM policy is:

"...that SI units of measurement shall be included in all ASTM

standards that do not contain a companion standard in 'hard'

metric units.

21
In addition to the general policy of ASTM "to include metric (SI) unit

in all of its publications," the main national standards committee in

the United States dealing with building standards—Committee E6 , Performance of Building Constructions—has established the following metric

policy

"E6 standards (old and new) submitted to Society for approval shall

be written henceforth with SI units and U.S. Customary in brackets,

e.g., 100 mm [3.94 in.] or 25.4 mm [1.00 in.]. Hard or soft conversion remains the prerogative of the subcommittee writing the

standards.

American Society of Heating, Refrigerating and Air-Conditioning

Engineers . The American Society of Heating, Refrigerating and AirConditioning Engineers (ASHRAE) has a standing metric committee, which

meets twice a year and is active in educating society membership on metric conversion. All ASHRAE publications will be in dual units com- mencing in 1981. The staff metric coordinator is Thomas C. Elliott,

New York, NY, and ASHRAE 's metric policy is as follows:

"1. All ASHRAE documents published after January 1, 1976, shall

be prepared using only SI units, or shall be prepared using

dual units, i.e., SI and conventional units, with the sequence

of units left to the discretion of the author or editor.

Exceptions in Handbook volumes, Standards, and special publications may be authorized by the responsible ASHRAE Metric

Committee.

2. Except where difficulties would be encountered in achieving

the stated purpose, the Handbook Series, starting with the

1981 Fundamentals Volume, shall be published using dual units.

Chapters presently utilizing SI metric only shall remain so.

3. Exclusive use of SI units shall be required in ASHRAE publications when it is determined by the Board of Directors to be in

the best interest of the membership. During the transition

period, the Metric Committee will continue to disseminate educational materials to prepare the membership for the eventual

exclusive use of SI units."

American Society of Mechanical Engineers . The American Society of Mechanical Engineers (ASME) has no metric coordinator: however, it has a metric consultant who serves as secretary of its Metric Study Committee.

The ASME is the sponsor of the Boiler and Pressure Vessel Code , and presently has no plans to publish a metric edition. Following is ASME '

metric policy (as updated in 1977):

"The Society supports a coordinated voluntary national program of

conversion to the International System of Measurement. ASME will

cooperate with other organizations and societies in implementing

22
this policy. The ASME interpretation of SI is contained in ASME

Guide SI-1, ASME Orientation and Guide for Use of Si-Metric .

All works, papers and periodicals published by the Society shall

require units to be in the International System (SI). Customary

units may also be included.

The Council directs the Policy Board, Codes and Standards to assure

that Codes and Standards shall be published in SI units at the

appropriate time as determined by industry, government, public and

society needs consistent with national plans for coordinating and

managing development of SI Standards.

American Society of Photogrammetry . The American Society of Photogrammetry (ASP) has the following statement in the Foreword to its publication

"American Society of Photogrammetry Usage of the International System of

Units:

"It is the policy of the American Society of Photogrammetry to

promote simplification and uniformity in usage of units of measurement by cooperating with other organizations in establishing common

use of the International System of Units (Systeme International

d' Unites) with the abbreviation SI and popularly known as the

'metric system, 1 and to use this system in all of its publications.

This standard was prepared by the standards committee of the

American Society of Photogrammetry to promote use of the International System of Units, to make the policy of the Society known,

and to make the rules of use of the SI units readily available to

the members of the Society."

This standard is largely based on and generally technically consistent

with Standard 1000 of the International Organization for Standardization.

American Society of Plumbing Engineers . This Society uses dual units

in its publications entitled, "Data Book, Volume I, Fundamentals of

Plumbing Design," 1979-1980 Edition, and "Solar Energy System Design,"

as well as an appendix on SI unit conversions. Customary units are shown first with SI "soft" converted units in parentheses. The Society's

metric coordinator is A. J. Morales, Sherman Oaks, California.

American Standard/U. S. Plumbing Products . This organization uses dual

dimensioning on cataloged products and its metric coordinators are

J. S. Genovese and J. H. Bauer, New Brunswick, NJ. In his response to

the inquiry Mr. Bauer stated, "As a member of a subcommittee of CICC, we have agreed to accept the tentative schedule [ANMC/CICC Metric Conversion Timetable] put forth by CICC."

Associated General Contractors of America . The Associated General Contractors of America (AGC) has the following metric policy:

23
"...If the (construction) industry is to go metric, a hard conversion is recommended where there is an economic advantage (e.g.,

reduction of number of sizes). This means that the sizes of building products will change. In order to insure sensible change,, sizes

will have to be coordinated and rationalized. A hard conversion

properly handled, involving dimensional coordination is thus necessary if the building and construction industry is to realize any

advantage from metric conversion."

The AGC has taken no position for or against metric conversion. The

AGC has had a metric conversion committee since 1974 and Campbell Reed,

Washington, D.C., serves as its secretary. This committee has recom- mended support of and participation in the December 2-3, 1980, Metric

Symposium.

Association of Wall and Ceiling Industries - International . This asso- ciation has published no data in the metric area. It has established

recently a task group on metric conversion from within its Technical

Committees. Mr. Gene Erwin, Washington, D.C. , is responsible for Association metric activity.

Bethlehem Steel Corporation . Bethlehem Steel has the following metric

policy:

"Bethlehem Steel recognizes that the metric (SI) system is to become

the predominant system in the United States. We intend to supply

metric-dimensioned products to our customers when it is practical

to do so—from their point of view as well as ours. We intend to

remain fully aware of the progress being made by our customers in

implementing their metrication programs in order that we can do what

is necessary at the best possible time.

The Corporation has had a Corporate Metrication Committee since 1973. It

is chaired by A. G. Oudheusden, Bethlehem, PA. The Committee is composed

of department heads and its purpose is to study and make recommendations

for converting operating procedures and practices, processes, facilities, products, etc., to the metric (SI) system so as to supply metricdimensioned products when market demand dictates.

Bethlehem can accept and supply metric orders for flat-rolled steel

products. Other products can be supplied on a soft converted basis,

i.e., structural shapes, castings, forging, etc. Structural bolts can

be supplied to metric ASTM specifications.

The Chairman of the Corporate Metrication Committee summarized, "...we

have seen little interest in metric conversion so far, except for a few

large steel customers with worldwide operations in the automotive and

equipment areas."

24
Bliss Steel Products Corporation . The President of Bliss Steel has been

involved in activities of the Contruction Industries Coordinating Committee of the American National Metric Council. In his response, he

stated "The timing on our metrication will depend upon the metrication

of the entire Building Industry.

Brick Institute of America . The Brick Institute of America (BIA) has

no formal metric policy. Its Engineering and Research Committee is acting as its Metric Committee, with Alan H. Yorkdale, McLean, VA, serving

as coordinator. The response from the BIA included the following:

"Approximately three (3) years ago, the brick industry of the United

States was surveyed by the Institute. The general questions related

to metric conversion and dimensional coordination, along with metric

conversion.

The result of the survey indicated a general wait-and-see attitude,

with approximately 80 percent responding that 'when and if conversion came about,' they were willing to convert to dimensionally

coordinated metric size units.

It is significant to note that all manufacturers who are now making

modular size standard units are, in fact, making 'metric modular 1 size units, within the tolerances of the material specification

standards. All units larger than 'standard' size are now modular

and will also satisfy 'metric modular.

There are, of course, several 'special' sizes, mostly regional in

manufacture and market area.

Building Officials and Code Administrators International, Inc . The Executive Committee of the Building Officials and Code Administrators

International, Inc. (BOCA) reviewed the subject of metric conversion in

June 1979. Final action on this subject was to be decided at the 1980

Annual Conference, with results in the 1981 Editions of the Basic

Building Code, Basic Plumbing Code, Basic Mechanical Code, Basic Fire

Prevention Code, and Basic Property Maintenance Code. The change will be

a soft conversion.

Business and Institutional Furniture Manufacturers Association . This

Association has a Metric Conversion Subcommittee which is a part of its

Engineering Standards Committee. The output of this Association could

be classed as part of the construction industry or the metal or wood

manufacturing industry.

One of the primary functions of this Association is the preparation of

safety standards. To date, it has published dual-dimensioned standards

on general office chairs, lateral files, vertical files, and upholstered

furniture flammability requirements. In the near future it expects to

25
publish standards regarding desks, office panels and partitions, and

lounge furniture in dual units.

Carrier International Corporation . Since 1975, Carrier Corporation has

had a metric policy and placed responsibility for control of SI metric

development and coordination services among divisions within the Corporate

Engineering function. Two divisions of Carrier—Carrier International

Corporation and the Elliott Company—both have implemented plans to meet

the demands for SI units in overseas markets. The coordinator in each

of these organizations is: Gerald Callahan, Corporate Engineering,

Syracuse, NY; John Grecean, Carrier International Corporation, Syracuse,

NY; and, Lionel Taylor, Elliott Company, Jeannette, PA.

Concrete Reinforcing Steel Institute . This Institute does not issue

materials standards. It does participate in the development of metric

specifications for reinforcing bars through the American Society for

Testing and Materials. It is expected that the 1983 edition of the

American Concrete Institute Building Code for concrete construction will

be in dual units—metric and English.

The response included the following statement:

"Our industry cannot produce metric sizes until it receives orders

for same. The U.S. structural engineers cannot design for metric

sizes until: (1) the Building Codes are adopted in metric, or

(2) the Federal government requires all construction it finances

to be in metric sizes and grades. Whenever these conditions are

met, conversion of our industry will be quite rapid as substitution

of present sizes from inventory is not difficult."

Copper Development Association . Mr. Arthur Cohen, Supervisor of Standards and Safety Engineering, New York, New York, serves as the focal

point for metric activities for the Association.

Gypsum Association. The Gypsum Association has a metric committee

consisting of 16 members. The Committee is chaired by R.P. Entz, of

Des Plaines, IL. Its Vice Chairman and Secretary are D.L. Cook of

Dallas, TX, and H.B. Carlsen of Evanston, IL, respectively. The Committee has developed a listing of gypsum products and soft converted

their sizes to metric equivalents. It has a position paper opting for a soft rather than hard conversion of board products if metric is adopted

in the United States. In response to a U.S. Metric Board call for

general research proposals a recommendation for a project was developed

with the objective, "To evaluate the effect and primarily the economic

impact to both producer and applier alike if panel and tile products were produced (sized) based on the 100 mm module as opposed to the present

4-inch module."

Halstead and Mitchell - Division of Halstead Industries . This organization to date has had no incentive to convert to SI units. Its

26
Engineering Department has had no difficulty in handling occasional

inquiries in SI units. The organization belongs to the Air-Conditioning

and Refrigeration Institute and this Institute's standards are published

in dual units at present.

Illuminating Engineering Society of North America . The Illuminating

Engineering Society (IES) adopted a policy in 1979 to use SI units as primary units in its new reports and technical publications. Inch-pound

units are shown in parentheses for soft (exact) conversion and in

brackets for hard (approximate) conversion immediately after the SI

units. The IES Lighting Handbook is being revised (1980) and will contain SI units as primary units and, where possible, metric values will

be nominal values.

Interior Design Educators Council . The organization has not taken an official position on the use of the metric system in teaching design.

However, some of its members do teach some of their design problems in

the metric system. The contact person within this organization is

Mr. Curt Sherman, Richmond, VA.

International Association of Plumbing and Mechanical Officials . The

International Asssociation of Plumbing and Mechanical Officials (IAPMO)

metric coordinator is John Meacham, Los Angeles, CA. The IAPMO added

metric equivalents to its Uniform Plumbing Code in 1977, and they are in

the current edition (1979) of the Code. In addition, metric equivalents

are contained in The Uniform Plumbing Code Illustrated Training Manual

and the Uniform Solar Energy Code . Other codes will be brought into line

as time permits.

International Conference of Building Officials . The International

Conference of Building Officials (ICBO) has drafted, for internal use,

proposed revisions to its codes and standards, in expectation that it

should be ready to integrate metric units into the publications when the

onstruction industry in general, has signaled it is ready to proceed.

ICBO's contact person is Donald Watson, Whittier, CA.

Manufactured Housing Insitute. The Manufactured Housing Institute (MHI)

has taken the following position relative to metric conversion:

"The Manufactured Housing Institute (MHI) supports the principle of

metric conversion but defers to the site-built housing component

of the shelter industry in pursuing change-over. MHI sees no com- pelling reasons to expedite conversion, although there appears to

be a consensus that benefits of total conversion should outweigh

the nominal direct costs."

In addition, the response included MHI ' s Metric Conversion Concerns:

"Considerable planning and coordination must precede conversion. Manufacturers will have to work closely with suppliers of raw materials and

finished components. The transition period may be difficult, for example:

27
1. There is a tremendous amount of technical documentation that must be

republished. Standards that have taken years to evolve through the

consensus process will have to go through it again to resolve which

way to round off measurements. The cost of replacing entire technical libraries must also be considered.

2. The materials purchased by the industry will not all be available

simultaneously in the metric system. Therefore, there will undoubtedly be periods of phasing out of English system materials and

phasing in of metric materials. This will require periods of dual

dimensioning and dual inventories.

3. The international building module of 100 mm and selected multiples

sounds simple enough, but at some point in time standard joist,

stud, and truss spacing must change from 16" (406.4 mm) to 400 mm

(15-3/4"). We will have to use up inventories of 48" wide sheets

of plywood, particleboard and ceiling panels.

4. The dual dimensioning problem and change-over date is not just a problem of purchased materials and inventories. It has significant

impact on plant production jigs, fixtures, and tooling as well.

5. Retraining people will be a significant task all by itself. Teaching

nontechnical people is sometimes difficult. The retraining will

involve not only the unskilled workers in the plants, but some people

who might be considered as having a reasonable education including

inspectors at all levels.

6. The Metric Conversion Timetable comes as somewhat of a surprise.

The dates shown indicate that the development of basic metric standards is well underway, but we have not yet seen any of them.

Perhaps the schedule has slipped.

Mechanical Contractors Association of America, Inc . This Association

has a Metric Coordinator, Thomas K. Whitesel, Jr., Washington, D.C.

Mobil Research and Development Corporation . The Mobil Research and

Development Corporation has a metric committee and its Corporate Metric

Coordinator is F. E. Ray of Princeton, NJ . In his response to the inquiry, the Metric Coordinator voiced a concern that there were no process

plant constructors participating in the Construction Industries Coordinating Committee of the American National Metric Council.

Monsanto Company . Monsanto follows prevailing practice in the country

where the facility is being constructed. When special purpose equipment designed and built in a "metric" country is used in the United

States, in some cases "inch/pound" drawings are made to facilitate

installation; in other cases the construction people interpret and

follow the metric drawings, as supplied.

28
Monsanto does not feel it is its role to pioneer the use of metric SI

units in the construction industry, but is prepared to move to the metric

system if and when the U.S. construction industry does so.

National Association of Home Builders . The Board of Directors of the

National Association of Home Builders (NAHB) passed the following resolution relative to metric converison on May 15, 1978:

Construction and Savings Committee

"WHEREAS, all industrialized countries other than the United States

have adopted, or are in the process of adopting, the metric system

as their sole method of measurement; and

WHEREAS, there is increasing discussion from within the United

States and abroad for the United States to establish a program

incorporating a timetable for converting from the English system

to the metric system; and

WHEREAS, the United States Government has enacted the 'Metric

Conversion Act of 1975' which declares a national policy of coordinating the increased use of the metric system; and

WHEREAS, leadership is needed within the construction industry to

implement metric conversion when it occurs; and

WHEREAS, various agencies of government are becoming involved in

metrication which could possibly lead to taking the initiative

away from the private sector; and

WHEREAS, the potential savings to the construction industry are enormous by an orderly conversion,

NOW, THEREFORE, BE IT RESOLVED that NAHB support the American

National Metric Council's initiative in channeling and organizing

the private sector's effort to date in making the ultimate changeover to the metric system an orderly and beneficial one."

The NAHB has been involved with metric activities for several years,

has had representation on the Board of Directors of the American

National Metric Council, as well as a number of Sector committees.

The homebuilders are concerned with the lack of documented evidence to

prove claims of savings to the construction community. There is concern that a conversion may cost the industry a sizable amount of money,

because of the complexity of the industry's make-up.

The NAHB staff persons assigned responsibility for metric involvement

are Robert Boras and Milton Smithman, both of whom are located at NAHB

headquarters in Washington, D.C.

29
Mr. Smithman concluded his reply with:

"We sincerely support the conference which is to be sponsored by

the National Institute of Building Sciences on the subject of

[Metric Conversion in the Construction Industry]. We believe it

to be very constructive to air the issues both pro and con with

the participation of all parties involved. Hopefully, this con- ference will result ultimately in some sort of unified position."

National Concrete Masonry Association . This association responded negatively to the inquiry and the response is included here in total.

"Our organization has been against metric conversion from the

beginning, and the more it is studied, especially with the Canadian

experience now in progress, our position remains unchanged.

"Since our product is made and sold only in the U.S., we see no advantage to changing to metric. The costs to convert to metric

will be in the order of $140 million with most of the money being

spent rather quickly since all the molds which are used for the

manufacture of concrete masonry would have to be made anew. There

are currently about 1500 different sizes and shapes of concrete

masonry being made in the U.S. and one concrete masonry manufacturing plant will normally make from 50 to 200 different sizes and

shapes.

"Our organization prints more literature on concrete masonry than

any other in the world and we employ metric designations in most

of our literature since it is read all over the world. Therefore,

we are not unfamiliar with metric dimensions - or its problems.

We find countries which have adopted metric sizes have had problems

on agreeing on common dimensions so metric is not an answer to

'being in step with the world. 1

"We are staying informed on metric progress, and view with alarm

how quickly some industries are adopting the principle. For international organizations, there is merit in going to some type of

metric scaling, but for domestic organizations, the costs of con- versions are horrendous without much economic benefit.

"We will have [a representative] at the meeting in December, but

not as an advocate of metric conversion.

National Electrical Contractors Association . The Metric Coordinator for

this association is Charles J. Hart, Associate Director, Services and

Codes, Washington, D.C. In his response to the inquiry, Mr. Hart stated:

30
"...the National Electrical Contractors Association does not believe

that it is in a position to either promote or to impede metric con- version in the construction industry. If such conversion is determined, we believe that it should be orderly and coordinated. We are members of the American National Metric Council and participate

in several sectors of the Construction Industries Coordinating

Committee.

National Forest Products Association . The National Forest Products

Association published a booklet entitled, "Lumber and Wood Products

Metric Planning Package," under the auspices of the Lumber and Wood

Products Sector Committee of the American National Metric Council. In

his response, the Vice President of Technical Services of the Forest

Products Association stated that the wood industries steadfastly held

to a policy of non-advocacy of metric conversion throughout the development of this booklet. After its completion, the Sector committee and

its components decided to adopt a holding action pending a positive indication of metric progress on the part of the Federal government or the

construction industry.

National Society of Professional Engineers . The National Society of

Professional Engineers is concerned with the professional, rather than

technical, aspects of engineering; therefore, its primary role with

respect to conversion to the International System of (metric) Units

SI, has been that of encouraging orderly transition and furnishing

information to the membership via the Society's publications.

The Society has adopted the following professional policy:

"PROFESSIONAL POLICY NO. 102-C

METRIC SYSTEM—CONVERSION TO

The National Society of Professional Engineers, recognizing the

advantages inherent in use of the metric system of measurement,

endorses the principles embodied in the Metric Conversion Act of

1975.

In implementing the Act, NSPE supports full conformance with the

SI metric standards of the International Bureau of Weights and

Measures and in the matter of spelling with the standards of the

consortium of English speaking countries of the world.

NSPE urges it members, chapters, and state societies to provide

any assistance it can to further the rapid conversion to the metric

system within the United States."

Portland Cement Association . The Portland Cement Association (PCA) has

a Metric Committee whose principal objectives are to:

31
1. provide such technical assistance to the Canadian Portland Cement

Association as may from time to time be requested to implement their

metric needs;

2. keep informed on the various activities directed to promoting U.S.

metric conversion, and, when deemed necessary, notify our member

companies on current events and important issues;

3. evaluate the probable impact on PCA operations which may eventually

result from U.S. metric conversion; and,

4. plan programs within PCA to implement metric conversion, but only

at such time as the nation voluntarily decides to convert and a national M-date has been established and accepted.

The PCA response included the following note:

"It must be clearly undersood, however, that PCA does not in any

way set the metric policies for the cement industry, nor does it

represent its members, collectively or severally, in any matters

concerning metric conversion. Metric policies, planning and programs are strictly the responsibility of each cement producer,

acting independently for its own interests, and, therefore, a consensus industry attitude towards metric conversion has not been

established.

The PCA has researched and prepared several hard metric publications

and design aids for the Canadian cement interests. All publications

written since 1978 contain soft conversion of English units.

Prestressed Concrete Institute . The Prestressed Concrete Institute (PCI)

has a Metrication Committee, chaired by Douglas C. Jeffords of Nashville,

TN. Mr. Daniel P. Jenny of Chicago, IL is PCI's Metric Coordinator.

PCI has the following metric policy, dated January 1978:

"The Prestressed Concrete Institute endorses metric conversion to

the SI system of measurements. It is imperative that the conversion be done in a well planned, orderly fashion in order to minimize the difficulties that will result from the conversion, as well as to assure that the various standards adopted for use in

the prestressed industry are logical and compatible. Hence, it is

the policy of the Institute to continue to monitor the steps being

taken toward metrication in the construction industry with the

view of assisting the conversion and achieving reasonable and

workable standards."

In his response, the Metric Coordinator included the following "Initial

Steps for Implementation of the PCI Board Policy on Metrication:

32
1. All new PCI publications including PCI periodicals will have soft

conversions, i.e., metric equivalents in parentheses, metric scales

on graphs where feasible, and metric conversion charts.

2. When existing publications are revised they shall have a soft

conversion.

3. PCI shall adopt the 100 millimeter module as a basic unit (approximately 4 inches).

4. PCI shall adopt a basic panel size of 1200 x 2400 millimeters

(approximately equivalent to 4.0 x 8.0 feet).

5. The Standardization Committee shall be directed to use this opportunity for the rationalization of a reduced number of shapes. When

reviewing and cataloging this information, it shall be looked at in

both hard (exact) metric units and customary (English) units.

6. PCI shall expand its educational activities to assist the members

in evaluating and understanding metric conversion, and the SI system

of measurement.

7. The Metrication Committee shall be responsible for developing a hard conversion metric plan and schedule and recommend the appropriate time for implementation."

Quaker Maid ~ A Tappan Division . This organization is awaiting the

resolution of differences between the paneling plywood industry and

gypsum paneling industry. One industry is ready to convert to a 1200 x 2400 mm panel, while the other wishes to maintain the 4' x 8' measurement. Until these differences are resolved, the cabinet and appliance

industry cannot proceed, as many cabinet dimensions have developed over

the years to efficiently use plywood paneling.

Red Cedar Shingle and Handsplit Shake Bureau . To date, the extent of

this organization's metric activities is the inclusion of metric units

on the labels of bundles of shingles and shakes, i.e.,

Society of American Registered Architects . This Society responded

saying that for several years a representative has been attending

meetings of the Design Sector of the Construction Industries

Coordinating Committee of the American National Metric Council.

Bernard L. Frishman, Silver Spring, MD, is Coordinator and Representative

for the Society.

Southern Building Code Congress International, Inc . The Southern

Building Code Congress International, Inc. (SBCCI) has no formal timetable for conversion to SI units, and feels the industry itself should

16" x 5/2

24" x 3/4

(400 mm x 5/50 mm)

(600 mm x 19 mm

)

33
provide information and guidance on which units it will convert to. A

metric conversion chart is included in all 1979 editions of the Standard

Codes, and SBCCI is beginning to incorporate metric units in Research

and Compliance Reports it issues on products and materials. The SBCCI

Board is considering including soft converted units for nonindustry

dimensions in its 1982 Standard Codes; i.e., stair dimensions, heights

and areas, door widths, etc.

Tishman Research Corporation . The Tishman Research Corporation has

neither a metric policy nor a metric coordinator. This organization

posed questions in its response to the inquiry which are answered at the

beginning of Part 2.

Underwriters' Laboratories, Inc . In 1972, Underwriters' Laboratories,

Inc. began including SI metric equivalents to the stated customary units

in its Standards for Safety . Most standards include soft converted

units; however, when the involved industry expresses the need, hard

converted values are used.

Union Carbide Corporation . Union Carbide's Metrication Coordinator is

C.S. Hines, South Charleston, WV. It has a metrication Steering Committee which includes contacts in all divisions and functional groups. The

Steering Committee meets twice a year and maintains . close contact otherwise by telephone and Metric Bulletins issued by the Coordinator. Some

of its executives have had overseas experience and are familiar with

international use of metric. Union Carbide produces and sells some products in metric in the United States and is preparing to do so in many

remaining products. Market demand and other considerations determine

the timing of implementation of Union Carbide's metric conversion plans.

United States Gypsum Company . This company has a major concern with

the replacement of the 4-inch module with the 100 mm module. It is

opposed to hard conversion of panel, tile, and block products. It

opposes neither "soft conversion" nor "hard conversion" of non-rigid

products which are sold in bulk and/or packaged in bags, boxes, cans or similar volumetric units.

U.S. Gypsum established a corporate policy in 1978, as follows:

"United States Gypsum Company recognizes the apparent inevitability

of the proposed use of metric (SI) units as a replacement for those

units such as inch, pound, and foot, generally employed in the

United States.

The conversion of rigid materials to "hard" metric sizes based on

the 100 mm module is not believed to be in the best interest of

the Company, the construction industry, and the public in general.

The manufacture of gypsum, wood and mineral fiber products in sizes

based on the 100 mm module would result in smaller sizes than are presently produced with the 4-inch module and therefore a loss of

34
manufacturing capacity, an increased use of energy, and a requirement for additional labor for installation. Therefore, it will be

Company policy to support change on a "soft" conversion basis only

on rigid products. In anticipation of such change, labels and

literature will have metric values added at such time as revisions

are made normally.

Conversely, 'hard' conversion of products sold by weight or volume

such as building plasters, joint compounds, fluid paints, and

adhesives would have little effect on capacity and therefore could

readily be converted at such time as metric is accepted in the

United States. Company policy will be to accept 'hard' conversion

of measurements for such products."

The Company carries dual labeling on a large percentage of its products,

much of its literature and all research reports carry dual units, and

it is presently converting asphalt roofing shingles to hard metric sizes.

Mr. R. P. Entz of Des Plaines, IL is the metric coordinator for the U.S.

Gypsum Company.

Weyerhaeuser Company . Mr. Jack Firkins, Tacoma, Washington, is the

Metric Coordinator for Weyerhaeuser . The company has issued a Weyerhaeuser Metric Practice Guide . Its Senior Management Committee adopted

the following policy in 1976.

"In recognition of increasing international trade, the national

policy of increasing metric use and the long-term benefits of

metrication, it is the policy of Weyerhaeuser Company to support

the adoption of metric units of measure known as the International

System of Units (SI). It is our desire that metrication should be

essentially complete by 1982. However, our adoption pace will be

established considering our international product involvement, new product introduction and the metrication activity and progress

nationally and within our industry segments.

Section 6, Item 4 of the Metric Conversion Act of 1975 instructs

the U.S. Metric Board to 'encourage activities of standardization

organizations to develop or revise, as rapidly as practicable,

engineering standards on a metric measurement basis, and to take

advantage of opportunities to promote (A) rationalization or simplification of relationships, (B) improvemments of design, (C) reduction of size variations, (D) increase in economy, and (E) where

feasible, the efficient use of energy and the conservation of

natural resources. 1 It is company policy to be actively involved

in the development and revision of standards and codes relevant to

the products we produce. This activity shall be coordinated through

appropriate industry associations and the American National Metric

Council.

To minimize costs and maximize the benefits associated with

metrication, thoughtful and coordinated planning is essential.

35
Within the corporate policy and procedures framework, each business

shall establish metrication objectives (soft conversion, hard conversion, rationalization, optimization) for its products and business practices, and outline a program for achievement. Manufacturing and support groups shall similarly establish metrication objectives and activities that directly support the business. Each

manager shall incorporate metrication activity plans in his annual

statement of goals and program and standards of performance and

communicate them to the Corporate Metric Review Committee."

2. 2 State Construction Related Metric Activities

The following construction related information concerning state metrication activity was extracted from the 1978, 1979, and 1980 Editions of

the Metric Yearbook , published by J. J. Keller and Associates, Inc.,

145 W. Wisconsin Avenue, Neenah, WI 54956. Also noted are those states

with metric committees.

Arizona - has a Metric Advisory Committee and has passed legislation

concerning the recording of land in metric measurements.

California - has a Metric Conversion Council to coordinate changeover to

the metric system and to keep in step with the national effort. There is

a licensed contractor on the Council. Two of the Council's major objectives are to encourage standardization, and to identify Federal, state,

and local laws and codes requiring amendment for metric conversion.

Colorado - has a Metric Advisory Board.

Connecticut - has a Metric Coordinating Committee. The state is a member of the Northeast Metric Coordinating Council which is comprised

of six New England states. In 1979, the State Legislative Research

Committee was actively researching all the measurement sensitive portions of existing statutes so that proper legislation can be amended

which will properly effect the change-over at one given time.

Delaware - All plans done in the Delaware Department of Transportation

include metric equivalents.

Florida - has a Metric Council which has a construction subcommittee.

A Florida Metric Plan was accepted by the Governor and Cabinet on November 21, 1978. One of the purposes of the planning effort stated

in the Plan is "To insure that all legal and procedural barriers

(federal, state, and local) to voluntary metric conversion are removed."

Indiana - Senate Bill 224 was introduced in the state legislature in

1979, and would have provided for a statewide referendum on mandatory

adoption of the metric system in the United States. This bill met the same fate as other bills in this subject area—inaction for the remainder

of the session.

36
Iowa - the Highway Division of the Iowa Department of Transportation

has a metric task force concerned with conversion of the highway system,

including signing, maintenance, stationing and construction contracts.

Maine - has a Governmental Metric Policies Committee.

Massachusetts - is a member of the New England Metric Coordinating

Council and has established a Northeast Metric Resource Center at the

University of Massachusetts.

Montana - has an Intergovernmental Metric Task Force.

Nebraska - a Nebraska Metric Board is currently in the process of

forming, with representation from industry, agriculture and education.

Nevada - has a Nevada Metric Committee. The Nevada Department of

Transportation established a timetable for completing a metric construction project, but the timetable is not being followed currently due to

"the interruption in the metrication activities at the state and federal

level," according to the metric coordinator for that Department.

New Hampshire - is a member of the New England Metric Coordinating

Council.

New York - has a New York State Metric Council. The state enacted a law in 1977 to make the metric system the "preferred" system in the

state, but allows use of customary units. In February 1978, Article 16

of the Agriculture and Markets Law (Weights and Measures Law) revision

became effective. It reads in part: "The Legislature hereby finds and

declares that voluntary and orderly conversion to the metric system of

Weights and Measures is of vital importance to the economy of the

state. It is hereby declared to be the public policy of this state to

encourage the gradual implementation of the metric system throughout

the state's government, industry, commerce, business, education, and

agriculture. " The New York State Metric Council conducted a study of

state laws to determine how often customary measurement units appear

therein.

North Carolina - has a Metric Planning Board.

North Dakota - as parts of the North Dakota Code are replaced, metric

equivalents are inserted in the replacement sections. Future legislation

is drafted with metric equivalencies inserted. In 1979, its legislature

enacted Senate Concurrent Resolution No. 4010, urging the United States

Congress not to pass any legislation mandating conversion to the metric

system in the United States. This concurrent resolution passed the

Senate on an unrecorded vote and passed the House by a vote of 46 to 45.

A concurrent resolution is not legislation and thus does not require a constitutional majority to pass.

37
Ohio - the Ohio Department of Transportation prepared a report on highway

metrication listing a five-phase experimental program which consisted of

(I) Design of two metric highway projects; (II) Construction of these

two projects; (III) Public Use and Adoption of Highway Signs; (IV) Public

Information; (V) Public Reaction. In a speech the Ohio Department of

Transportation Director stated, "...a true conversion to metric cannot

be done at the local level... all industry would have to convert to have

the U.S. become truly metric." In addition, he stated, "The primary

cost of conversion would not be as expensive as originally conceived.

Oklahoma - in Oklahoma the metric system has been jointly recognized with

the customary system for some time and can be used for any commercial

purpose.

Oregon - the metric system has been jointly recognized with the customary

system and can be used for commercial purposes. A project of the Oregon

Department of Transportation involved design and preparation of contract

documents utilizing the metric system for a highway improvement project.

Two bridges have been completed using metric measurements.

In 1979, another metric construction project was completed successfully

by the Oregon Department of Transportation. This small effort included

replacing an antiquated bridge with a culvert.

In addition, a field survey has been completed on a metric bridge

replacement project and it is now in the design stage. The Department

of Transportation has also been involved in preparation of right-of-way

documents for a metric highway improvement project.

South Carolina - has a Metric Advisory Committee.

Tennessee - has a Metric Conversion Committee.

Texas - has a Metric System Advisory Council. Two information surveys

have been completed, one dealing with a computer search of Texas statutes

for frequency of occurence of measurement units to determine how much

adaptation would be necessary to effect metric conversion of existing

statutes; and a survey of colleges and universities to determine whether

they had metric courses in progress.

Vermont - has a Metric Coordinating Council. Its 1979 work plan included

as a goal the preparation of a 10-year state plan for the conversion

to Metrics for the State of Vermont and included actions appropriate for

the executive and legislative branches of state government, as well as the Vermont Metric Coordinating Council. The Council has a subcommittee

on Building and Construction.

Wyoming - According to a state bridge engineer in the Wyoming State

Highway Department, "The only metric activity we have undertaken in 1979

is to include soft metric conversion in our "Specification for Road and

38
Bridge Construction" which will be published in 1980. We have shown the

metric equivalents in parentheses after the U.S. units, and the metric

equivalents are in accordance with ASTM E380-76."

39

PART 3 - TECHNICAL IMPLICATIONS OF METRIC CONVERSION IN THE

CONSTRUCTION INDUSTRIES

3. 1 General Aspects

What we loosely call "metric" is a comprehensive measurement system

with a decimal base, derived from the metric system which was developed

in France during the last decade of the eighteenth century to replace a variety of non-standard "primitive" measures. The modern metric system —which is known as "SI," for the French term "Systeme International

d'Unites" —is fixed by international agreements which include the U.S.

as a signatory. SI includes units for every physical quantity. Metric

usage has been legal in the United States since 1866, and all customary

units used in the United States have been defined in terms of metric

units since 1893. SI units are already widely used in some engineering

disciplines, such as electrical engineering, illumination engineering,

and acoustical engineering.

The American Society for Testing and Materials (ASTM) standard ASTM

E380-79 [1] and the Institute of Electrical and Electronic Engineers (IEEE)

Standard 268-1979 [2], both titled "Standard for Metric Practice," are recognized as key standards. Formerly, these two standards formed the

basis for American National Standards Institute (ANSI) Z210.1, "American

National Standard for Metric Practice." However, the 1979 editions

differ marginally, so neither has been endorsed as an ANSI standard.

The construction community has its own supplementary standard to ASTM

E380, ANSI /ASTM E621-78 [3], "Standard Practice for the Use of Metric

(SI) Units in Building Design and Construction." This standard sets

out rules and recommendations for the use of SI units in design and construction, discusses special considerations in the selection of units,

provides tables of preferred and acceptable units for various discipline

groups, including examples of typical applications, and contains a set

of conversion factors for the most common units used.

The availability of these standards makes it possible to select correct

SI units for data presented in metric units only, or in dual units, and

enables values to be converted with an appropriate degree of precision.

The matter of selection of "preferred" metric values is addressed in

detail in NBS Technical Note 990, "The Selection of Preferred Metric

Values for Design and Construction" [4]. The Technical Note provides

a rationale for preferred numerical values, gives guidance on conversion decisions, and includes a methodology for manual or automated

conversion of values in standards and technical documents.

41
3. 2 A Comparison of Features of SI and U.S. Customary Units

When appraising the merit of alternative measurement systems in practical

use, especially in building design and construction applications, it is

desirable to compare the features of the respective "systems. " (See

table 3-1.) In discussions to date, the debate seems to have remained

in the scientific realm among supporters of SI, and in the popular domain

among people opposed to change from U.S. customary units —with little

exploration of common ground.

The metric system, despite its new and foreign names—even in France—was adopted by one country after another, not by force, but because of its

intrinsic features in simplifying communications, specification, calculations, measurement, and control. The founders of the system had taken

heed of their brief to develop a universal and permanent system, based

on rational precepts. While the first objective was to replace the

great diversity of measures then in use in France and Europe, both in

nomenclature and magnitude of units with the same name, the features

suggested in the 1790's included: coherence, decimalization, and the

designation of absolute, reproducible standards, all of which have

remained features of SI, the modern metric system.

From a construction industry viewpoint, the key features in SI are the

reduction in the number of units of measurement, coherence (one-to-one

relationships) between units, and the availability of decimal prefixes

to select working units which preserve simple numerical values.

3. 3 On Units and Numbers

To understand the implications of a measurement system, it is important

to appreciate the role of units and numbers, because it is in this

respect that SI and U.S. customary units differ most.

Any measuremment statement, or "numerical value," is a combination of a unit and a number; the unit represents the reference quantity but would

make little sense on its own, while the number indicates the multiple

of the reference quantity, and, again makes little sense on its own.

(An exception occurs in tabulations or drawings, where a general statement of the reference quantity makes it possible to represent numerical

values by a number only; e «g«, all dimensions are in millimeters.)

U.S. customary units for length, capacity, and mass date from the middle

ages, where an "additive system" of multiple units was used to indicate

magnitudes; for example, a precise statement required pounds and ounces,

or feet, inches, and fractions. (The additive system goes back to

antiquity and is still in use in units for time [year, month, week, day,

hour, minute, and second] and plane angle [degree, minute, and second of arc ] .

)

While an additive system can be used to measure precisely, any mathematical operation which is performed on the "numbers," becomes complex,

42
Table 3-1: Concepts in Measurement: Comparison of SI and U.S.

Customary Units

CONCEPTS SI (METRIC) UNITS U.S. CUSTOMARY UNITS

1. Completeness SI has a unit for every physical

quantity

Multiple units exist for most physical quantities, but are supplemented by metric or SI units in many fields.

2. Uniqueness SI has only one recognized unit

for any one physical quantity.

(For practical reasons, a number of non-SI units or multiples

are accepted — units for time,

angle, and multiples such as hectare, liter, metric ton.)

A variety of units exist for physical quantities, often for special

applications only. For example,

without counting superseded or special units, there are 9 units for length, 5 for mass, and 7 for volume or capacity.

3. Coherence SI units are all coherent, that

is, they have a one-to-one re- lationship to each other, based

on their unit derivation according to the laws of physics.

Customary units have only limited

coherence, and result in the introduction of factors other than 1, when changing from one unit to another; for example, 2,3,4,6,8,

9,12,16,20,22,24,27, etc.

4. Decimalization SI uses standard decimal prefixes

(powers of 10) to alter the mag- nitude of the reference quantity.

These prefixes merely change the position of the decimal point,

not the digits in a number. The

prefixes are internationally

used and understood.

Large or small values are trans- formed into a different, non- decimal unit, except for the mil

(1/1000"), the square (100 ft 2 ), and the kip (1000 lbf). The ratio

between units, or factor, alters

the numerical values in calculations .

5. Unit Names SI unit names, except for traditional metric names taken from

Greek or Latin words, are derived from the names of great

scientists, which are the same

in all languages.

Customary units have names based on words in the English language.

These words have no meaning in other

languages. In some instances, the same name is used for different

magnitudes

6. Symbolization

and Rules

SI units and prefixes are represented by internationally

agreed letter symbols, which

have the same meaning regardless

of surrounding language or script. SI has agreed rules

for the use of units, symbols,

and numbers.

Unit names can be represented by

symbols (ft, lb, qt), signs (", ', °), or abbreviations (fps, psi,

cfm) . Their use relates to the

English language context only.

There are few formal rules on unit

use

7. Reproducibility SI units are scientifically defined to allow their accurate determination anywhere in the

world, except for the kilogram

which is based on an artifact.

U.S. customary units have been defined in terms of metric or SI units, e.g., 1 ft = 0.3048 m.

8. Universality SI units are "international"

and represent the official measurement system of most nations of the world. An international governing body (CGPM)

maintains the system and its

rules, including periodic

review.

U.S. customary units represent a national measureaent system, not used

outside the United States.

43
even simple addition and subtraction. Multiplication and division is

time consuming as all values have to be converted to the lowest common denominator (e.g., 4'-10" = 58") or else decimalized (e.g., 4'-10" = 4.833') before such operations are commenced, and then reconverted afterwards. Moreover, in division, the fractions available may not be sufficient to give a precise result, so that the parts differ. This "fudge

factor" frequently occurs in stairs, where the division of floor-to-floor

height (in feet and inches) into an equal height of riser (in inches

and fractions) generally leaves a small residual fraction which is

distributed over a number of risers.

From the start, metric measurement looked for a direct relationship to

the decimal system of numbers. The first application of a decimal

system, indeed, occurred in the United States where decimal currency was introduced some years before the metric system was conceived and finalized in France. Metric is "decimal," and the originators of the system

even tried unsuccessfully to decimalize time and angular measurement.

From a productivity point of view, metric operations would be simpler,

quicker, and less error-prone, because units follow the decimal number

pattern by having decimal relationships only.

In all other nations that have changed to metric units, proponents and

opponents have contrasted "a national metric system" and "a familiar

customary system." People as well as computers work better with decimal

units than with compound (additive) values, and this may explain why

those groups whose work predominantly involves computations or measurement decision, such as building designers and engineers, have been supportive of an early change to SI. Increases in the productivity of

design and documentation activities using metric units have been reported

from other English-speaking countries.

3.4 Coherent Units

All units in SI are "coherent," that is, they relate to each other on a unity or one-to-one basis, without any factors or ratios as in the U.S.

customary (or inch-pound) system. All units in SI are exclusively

derived from seven base units representing fundamental physical quantities (length, mass, time, electric current, [thermodynamic] temperature,

amount of [molecular] substance, and luminous intensity) and, in some cases, also from two supplementary units (plane angle and solid angle).

Five of the nine units are already in use in the U.S. customary system.

Derived units are formed by multiplication, division, or compounding of

fundamental units, and some derived units have special names.

Part 6 provides practical applications of coherent units in energy

design, but for the purposes of illustration, coherence can be understood

better when the relationships of the already familiar unit for power and

heat flow, the watt (W), are examined:

44
Electrical power: 1 W = 1 V«A (1 watt = 1 volt x 1 ampere)

Heat flow, energy, or . . T/ '

. ... , . , JN

. . 1 W = 1 J/s (1 watt = 1 joule per second) work per unit time:

Work or energy per 1 W = 1 N •m/ s (1 watt = 1 newton meter per

unit time: second)

Expression in terms 1 W = 1 kg»m2 /s 3 (1 watt = 1 kilogram meter

of SI base units: squared per second cubed)

System coherence not only facilitates calculations, but simplifies comparisons; for example, the watt (W ) would be used in SI for all forms of

power and heat flow, thus allowing direct comparisons between alternatives or systems. The watt will remain where it is now used, and replace

the following U.S. customary units: Btu/h, Btu/min, Btu/s, fflbf/h,

ft«lbf/min, ft»lbf/s, horsepower (boiler), horsepower (electric), horsepower (550 ft»lbf/s), horsepower (water), and the ton (refrigeration).

3 . 5 Decimalization

The decimal number system, which uses the base ten, is in worldwide use,

and its number symbols are understood regardless of language or sur- rounding script. Each symbol has an absolute value as well as a value

of position, so that numbers can be written as a linear combination of

powers of ten; for example:

123 456 [one hundred twenty-three thousand four hundred fifty-six] really

means: 1 x 10 5 + 2 x lO 4^ + 3 x 10 3 + 4 x 10 2 + 5 x 10 1 + 6 [x 10°].

Approximately 400 years ago, the concept of positioning was extended to

include decimal fractions, using negative powers of ten to the right of

a decimal marker, and this innovation made it possible to accurately

express divisions, complex numbers, and all values smaller than one

(1.0). It is no longer necessary to express fractions by means of a numerator and denominator, but as a decimalized value; for example, one sixteenth (1/16) becomes 0.0625, one tenth (1/10) becomes 0.1. The profound merit of decimalization of fractions was grasped very quickly and

mathematics and physics advanced significantly; for example, making

possible the expression of logarithms.

Decimal measurement systems were advocated as early as the 16th century

to replace the variety of medieval measures then in use, but a spirit

of revolution against outdated practices to bring about change was needed. The concept of decimal prefixes (words and symbols signifying

the multiplication of a unit by a power of ten; for example: kilo (k)

for 10 3 or milli (m) for 10- 3

) provides simple numbers—instead of

2500 grams, 2.5 kilograms can be used; or in lieu of 0.010 meter, 10

millimeters can be used. Decimal prefixes (or factors) do not change

45
the digits, only their position relative to the decimal point. The only

factor that appears in metric calculations is ten (or a power of ten),

and the unit name is retained, even though the prefix may be changed.

In building design activities, decimalization combined with coherent

units greatly facilitates calculations and decision-making. The value

of decimal units has also been recognized in U.S. customary measurement;

wherein the mil represents one thousandth of an inch (0.001") and is used

in precision measurement; the building square represents 100 square feet

(ft^); the kip represents 1000 pound-force (lbf), and the chain of

feet, or 4 rods, has been divided into 100 links for ease of calculation.

3. 6 Metric Practice - or, Rules for the Use of SI

In contrast to customary measurement which has no explicit book of rules

for the selection and use of units, their presentation and symbolization,

and numbers used in conjunction with units, SI is accompanied by an internationally agreed set of rules and recommendations to ensure con- sistency and to avoid misunderstandings. These rules are mostly commonsense prescriptions which, with a little practical application, are easily learned.

ANSI/ASTM Standard E621-78, deals with "rules and recommendations for

the presentation of SI units and symbols" in table 5, and with the

"presentation of numerical values with SI" in table 6.

A number of metric practice guides for specific disciplines has been

prepared by professional societies or industry associations, as well as individual corporations. These are included in Part 9 of this report.

The surveying and mapping community has developed a comprehensive and

thorough "Metric Practice Guide for Surveying and Mapping" [5], issued

in March 1978 by the American Congress on Surveying and Mapping.

3 . 7 The Practical Application of Measurement

Measurement units are used in a number of different ways, from approximations to very precise measurements. The impact of metrication, correspondingly, would have different overtones.

3.7.1 Estimation of Magnitudes . Estimating magnitudes in terms of

reference quantities is a "learned" aspect of measurement and principally involves memory and judgment. For example, if one hundred people

are asked to estimate the length of a dollar bill, in inches, a normal

distribution is likely to result, with some estimates stating a length

that is far too short, and some far too long. Estimating temperature

or speed is more difficult, and that of force, pressure, or power almost

impossible without some form of measuring instrument. In estimating, we use "mental images" or recognition points, such as one's own height,

46
reach, or fingerspan, and the main task in metrication would be to

generate a new data bank of learned names, relationships, and magnitudes

for meaningful assessment of physical factors. The need to "relearn"

causes objection to change by some.

3.7.2 General Communication of Measurement Information . The communication of measurement data can involve either estimates or approximations,

or highly precise measured data. For either communication, the receiver

of the message must be in a position to assimilate and process the

message in a meaningful way. For example, if temperatures are given in

degrees Celsius (°C) only, an association between numerical value and

sensation of comfort (cold, cool, mild, warm, hot) would soon be

obtained. However, if both a familiar reference (in degrees Fahrenheit)

and a metric reference (in degrees Celsius) are given, the unfamiliar

value would be selectively blocked out with almost no long term memory.

Where the precise communication of measurement information is essential

to a task, such as calling out values obtained by measurement to a person

who records them, it is essential that both the measurer and the recorder

are fully familiar with the units and values that are used.

3.7.3 Descriptive Information in Written, Typed, or Printed Data . Descriptive information in "software," such as standards, technical data

sheets, textbooks, drawings, and the like, requires compactness, lack of

ambiquity, and consistency in presentation. In most instances, metric

data would be advantageous.

The largest part of initial activity in metric conversion would involve

software, to be prepared either in metric units only, or in dual units

for the duration of a transitional period. Metric practice information

would be needed to allow people in the construction community to

assimilate metric task information.

3.7.4 Calculations and Computation . As already indicated, metric

measurement was designed for greater productivity in all mathematical

processes involving measurement decisions. The concepts of unique units,

coherence, and decimalization combine to give greater speed and fewer

errors. Engineering calculations, in particular, would benefit. Architectual documentation, with only one measurement unit for length—the

millimeter (mm) —would be simplified significantly, and check-outs for

accuracy facilitated.

3.7.5 Practical Measurement in Production and Construction . To measure

magnitudes of physical quantities such as thickness, mass, thermal properties, electrical properties, etc., any measurement system will suffice.

However, if comparisons are to be made with international standards, or requirements set out in metric terms, the use of metric measuring devices

would be preferable, rather than the use of non-metric devices and

subsequent conversion.

47
Precision in measurement is a function of the following: accuracy of

the measuring instrument, accuracy of the operator (reader) and/or transcriber, and the graduation of the instrument. For example, with a measuring tape graduated in inches only, measurements can be made to the

nearest whole inch, while smaller intervals have to be interpolated by

judgment. Normal steel tapes for construction measurement are graduated

in multiples of 1/16", so that measurement can be laid out or read to

the nearest 1/16". Similarly, metric construction tapes are graduated

in millimeters, so that measurement can be effected to the nearest millimeter (mm). The metric graduation will encourage more precise measurement and would be likely to lead to fewer deviations in additive measurement during production, layout, or construction. Conversely, temperature

readings can be made with greater precision on the Fahrenheit (°F) scale

than on the Celsius scale (°C), due to the finer graduation of the

Fahrenheit scale.

In production and construction measurement, the use of metric units

could generally increase measurement precision.

3.7.6 Quality Control, Testing, and Research . Quality control in production requires precise measurement to ensure that product characteristics remain within specified limits; that is, fall within permissible

tolerances. In general, the use of millimeters for the measurement of

length, width, depth, thickness, diameter or radius, warping or twisting,

and squareness would facilitate quality control operations.

A high percentage of testing and laboratory work in product manufacture

already is carried out in metric units.

3.8 Metric Units for Use by Tradesmen and Site Personnel

Considerable attention has been paid to metric (SI) units for building

designers and other professional groups. However, most practical tasks

for measurement in production and construction are carried out by

skilled and unskilled workers, to whom the change of measurement units

may be a cause for some concern.

In the construction environment, the number of units required to be used

will reduce, so that the learning situation is not as great as imagined

at first sight. Precedent has indicated that there is little merit in

"overtraining" personnel, especially in aspects of the metric system that

will never be applied in practical use. For most tradesmen and on-site

personnel, training on the job is the best approach as it puts metric

concepts into a practical perspective.

Table 3-2 shows the most common metric units that would be used in various

construction-related activities.

48
Table 3-2: Key Metric Units for Use on the Job

ACTIVITY QUANTITY UNIT(S) SYMBOL(S)

BLOCK AND BRICK MASONRY

Linear Measurement

Area

Volume (of mortar) Kass (weight)

millimeter, meter

square meter

cubic meter kilogram

mm , m

m

2

3 m

kg

CARPENTRY Linear Measurement

Area millimeter, meter

square meter mm , mm

2

CONCRETE WORK Linear Measurement Area

Volume Temperature (of ingredients)

Mass (weight) (of ingredients)

Capacity (water) Cross-section (of reinforcement)

millimeter, meter

square meter

cubic meter

degree Celsius metric ton (1000 kg) liter square millimeter

mm , m m

2 m

3 °C

tLmm2

ELECTRICAL SERVICES

*already in common

use

Linear Measurement

Frequency

Power Energy Electric Current Electric Potential

Electric Resistance

millimeter, meter

*hertz, kilohertz

*watt, kilowatt megajoule, *kilowatthour (3.6 MJ) *ampere

*volt, kilovolt

*ohm, kilohm

mm, m

Hz, kHz

W, kW

MJ, kWh

A

V, kV

n, kn

EXCAVATING Linear Measurement

Volume

Mass (weight)

meter

cubic meter

metric ton (1000 kg)

mm 3

t

GLAZING Linear Measurement

Area

Mass (weight)

millimeter, meter

square meter kilogram

mm , m

m

2 kg

LAND SURVEYING Linear Measurement

Area

meter, kilometer

square meter, hectare (10 000 m)

,

square kilometer

m, km m , ha

km2

MECHANICAL SERVICES Linear Measurement

Volume

Capacity Airflow (Velocity) Volume Rate of Flow

Temperature

Force

Pressure, Stress

Energy, Work

millimeter, meter

cubic meter

liter (1 m = 1000 L) meter per second

cubic meter per second, liter per second

degree Celsius

newton, kilonewton

kilopascal, magapascal

kilojoule, megajoule

mm , m m

3 Lm/

m

3 /s L/s

°C

N, kN

kPa, MPa

kJ, MJ

PAINTING Linear Measurement

Area

Capacity (of paint)

meter, millimeter

square meter

liter, milliliter

m , mm

m

2 L, ml

PAVING, PLASTERING,

TILE LAYING

Linear Measurement

Area millimeter, meter

square meter

mm , m

m

2

PLUMBING (See also: Mechanical

Services)

Linear Measurement

Capacity

Mass (weight) Pressure

meter, millimeter

liter

kilogram, gram kilopascal

m , mm

Lkg, g kPa

ROOFING Linear Measurement

Area

Slope

millimeter, meter

square meter millimeter per meter (or use numerical r»tioj

mm , m m

2 mm/ ra

SEWAGE DISPOSAL,

SITE DRAINAGE

Linear Measurement

Area Volume

Capacity

Slope

meter, millimeter

square meter, hectare (10 000 m) cubic meter

liter millimeter per meter (or use numerical r«tio)

m , mm m

2

, ha m

3 Lmm/m

STEELWORK Linear Measurement

Mass (weight)

millimeter, meter

metric ton (1000 kg) , kilogram

mm , m

t, kg

TRUCKING Distance

Volume

Mass (weight)

kilometer

cubic meter metric ton (1000 kg), kilogram

km

m

3 t, kg

49
3. 9 Metric Measuring Instruments

One of the real costs of metric conversion is the purchase of metric

measuring instruments, such as drafting scales, steel tapes, weighing

devices (scales), gauges and dials, levels with graduations or markings,

micrometers, test sieves, and some specialized items for quality control

or performance measurement. The cost of procurement can only be reduced

if normal replacement cycles are used to acquire metric rather than

customary instruments. In some instances, it would be more practical to

effect a partial replacement; for example, the purchase of a blade with

metric graduations for a steel tape rather than purchasing the entire new unit, or a metric dial for a pressure gauge rather than a new gauge.

Although not preferred in the long run, tapes, scales, and gages may be

obtained with a dual readout for use in a transitional period; for

example, steel tapes are commercially available now with graduations

both in inches and fractions on one edge of the blade, and graduations

in millimeters on the other.

Special care should be exercised in purchasing decisions to make sure

that the "metric" instruments feature correct units and standard graduations. For example, tapes graduated in centimeters (cm) are widely sold

for general use, while the construction community probably would use millimeters (mm); the purchase of the wrong measuring devices could

create confusion rather than simplification. Similarly, a variety of

gages imported from traditionally metric countries are calibrated in

non-SI units, such as the bar, millibar, atm (standard atmospheres),

kgf/cm^, etc., rather than in pascals (Pa) or kilopascals (kPa).

Uninformed purchasing could cause confusion, apart from waste of money.

At this time there are no national standards that outline preferences

for metric drafting scales, steel tapes, surveying instruments, mass scales and other weighing devices, thermometers, pressure gages, etc.,

and it appears that the industry would benefit from standardization

efforts. ASTM Standard Ell-70 (Reapproved in 1977) [6], dealing with

test sieves, does list metric sieve designations as standard sizes

corresponding to those recommended by ISO, and also includes alternative

designations

.

A number of American multi-national corporations produce preferred metric

measuring instruments in other countries and are well equipped to serve

the needs of the U.S. construction community during a transition to

metric measurement.

3. 10 Metric Standards

The Metric Conversion Act of 1975 specifically addresses the subject of

metric standards and states in Section 6:

50
..."In carrying out this program, the [United States Metric] Board

shall—(4) encourage activities of standardization organizations

to develop or revise, as rapidly as practicable, engineering standards on a metric measurement basis, and to take advantage of opportunities to promote (A) rationalization or simplification of relationships, (B) improvements of design, (C) reduction of size variations, (D) increases in economy, and (E) where feasible, the efficient use of energy and the conservation of natural resources;"

Most of the voluntary national standards-writing organizations in the

United. States have policies to use or include metric (SI) units in their

standards, although not necessarily as "hard-converted" and preferred

values. Where available, the policy decisions of relevant building

design and construction standards-writing organizations are given in

Part 2.

3.11 Metric Building Codes

There are no fully metric building codes or model codes available in the

United States although some major code-developing organizations have

decided to include metric equivalents in future editions. There are a number of options, ranging from the use of dual measurement units (with

varying degrees of rounding and rationalization), to the preparation of

dual documents with separate, preferred values for use with each measurement system. The latter approach would provide the most convenient numbers for designers, manufacturers, contractors, and building controllers

but is likely to require considerable investigation and inter-industry

discussion to arrive at preferred values.

3.12 Technical Reference Material, Handbooks, and Textbooks

At present, technical information for professional and other personnel

in the construction community is predominantly in U.S. customary units,

although some professional institutes and societies are rapidly developing a metric data base. Scientific handbooks and college physics texts are largely in metric units, although they do not always adhere to

correct SI units and presentation.

The American Institute of Architects, in conjunction with Wiley

Interscience , has prepared the "AIA Metric Building and Construction

Guide" [7], a comprehensive and thorough basic reference document for

building designers and others interested in the application of SI in

construction.

A number of engineering textbooks dealing with the change to metric (SI)

units have been published. "Metric Units in Engineering—Going SI," by

Professor Cornelius Wandmacher [8] provides a useful and comprehensive

general text to acquaint engineers and engineering students with the

concepts, relationships, and practical application of SI.

A comprehensive metric bibliography is provided in Part 9.

51
REFERENCES

1. Standard for Metric Practice, ASTM E380-79; American Society for

Testing and Materials, Philadelphia, PA; 1979; 42 pages.

2. Standard for Metric Practice, IEEE Std. 268-1979; Institute of

Electrical and Electronics Engineers, New York, NY; 1979; 47 pages,

3. Standard Practice for Use of Metric (SI) Units in Building Design

and Construction, ASTM E621-78; American Society for Testing and

Materials; Philadephia, PA; 36 pages.

4. The Selection of Preferred Metric Values for Design and Construction;

NBS Technical Note 990; National Bureau of Standards, Washington,

D.C.; December 1978; 83 pages.

5. Metric Practice Guide for Surveying and Mapping; American Congress

on Surveying and Mapping, Falls Church, VA; March 1978; 12 pages.

6. Wire-Cloth Sieves for Testing Purposes, ASTM El 1-70 (reapprovved

1977), American Society for Testing and Materials, Philadelphia, PA;

1970; 5 pages.

7. AIA Metric Building and Construction Guide, Wiley Interscience , Inc.;

New York, NY; 1980, 154 pages.

8. Metric Units in Engineering—Going SI, Cornelius Wandmacher;

Industrial Press, Inc., New York, NY; (1978); 302 pages.

52
PART 4 - METRIC CONVERSION AND DIMENSIONAL COORDINATION IN BUILDING

4. 1 Dimensional Coordination: Background

In an industry where most tasks involve dimensional control of products,

components, assemblies, and building elements, as well as their combination and fitting to form buildings and structures, dimensional standardization is an essential ingredient of cost-effective operations. The

alternative of random sizes would involve extensive cutting or make-up

activity, and result in waste of materials as well as low productivity.

Dimensional coordination simply is a rational approach to the determination and selection of preferred sizes for building products, and of preferred dimensions for spans and spaces, based on a common denominator,

the "building module" or basic unit of size. For this reason, it is

also referred to as "modular coordination. "

In historical building activity, many components were custom made or shaped, or produced in small quantities, so that special sizes carried

no significant cost premium. A concept of preferences emerged, based

on whole multiples of the customary units of measurement, the foot and

the inch. Most preferred among these values were those that formed a simple doubling series, for example:

1" >

2" >

4" >

8" 16"

(l'-4") D> 32"

(2'-8") 0

64"

(5'-4")

3" D>6" >

12"

(V-0") >

24"

(2'-0") t>

48"

(4'-0") 0

96"

(8'-0")

These ranges are related by a factor of three, so that any size of the

inch-based series, when trebled, equals a value in the foot-based series.

Examples of customary product sizes from these two ranges abound, and

include brick, block, floor and ceiling tile, panels, planks, and many

assemblies. In addition, multiples of selected dimensions were used

for functional sizes and spaces in buildings, for instance whole multiples of the foot—2' (24"), 3' (36"), 4' (48"), and 5' (60")—as planning

modules. This system works quite well, except for the occasional mismatch in dimensions which is sorted out by design detailing or construction fitting on-site. Some minor inconvenience was caused by having to

work with essentially three measurement units: feet, inches, and common

fractions of inches.

With increasing industrialization of the 20th century, proposals emerged

in the 1920's and 1930's for a comprehensive and rationalized approach

to design and construction dimensions, and related building product

sizes. The best known pioneering work was done by the American industrialist Albert Farwell Bemis (1870-1936), who proposed a 4-inch module

as basic unit of size for buildings as well as building components, and

53
who developed a comprehensive approach to coordination, subsequently

referred to as "modular coordination." The 4-inch unit of size was given the symbol M (for module), and whole multiples of M were preferred

for all dimensions. The system also included a modular grid, with a 4-

inch grid interval, for the precoordination and positioning of building

elements and components. After Bemis' untimely death, his ideas became

the basis for a national standards effort in "the coordination of dimensions in building," and a series of national standards became available

after 1945. Masonry units, such as clay brick, concrete block, and clay

flue linings were in the forefront of the change to modular dimensions

based on the 4-inch module.

4. 2 Metric Dimensional Coordination and the International Building

Module

The ideas of modular coordination were picked up in post-World War II

Europe, and they became the basis of the industrialized reconstruction

program in a gigantic demonstration of how greater productivity can be

achieved by the use of standardized dimensions rather than random

choices. European nations used a 100 mm (10 cm) building module and

found this basic and decimal unit to be of a near-optimum size to reduce

variety while simultaneously retaining simplicity of numbers. The

European efforts, in both Western and Eastern European countries were followed by extensive adoption of the principles in South and Central

America and Asian metric countries. Subsequently, the 100 mm module was used as the basis of international (ISO) standards, prepared within the

ISO Technical Committee 59, Building Construction, which was 52 member

nations and 32 actively participating in the work. The international

building module was given further emphasis when all English-speaking

countries that changed to metric in the 1960's and 1970's adopted this

module and selected mutliples in the determination of their dimensional

preferences in building [1].

4. 3 Metrication and Dimensional Coordination

Although a separate issue from metrication, dimensional coordination in

the construction industry becomes like a Siamese twin: without at least

a partial adoption of modular and preferred sizes during the change, one

of the greatest opportunities of metrication in construction would be

missed. In the United States, this fact is already widely appreciated,

and both the U.S. Metric Study in 1970-71, and the GAO Metric Study in

1976-78 found support for this proposition, even though a considerable

percentage of respondents did not give a definitive reply.

Question 14. h in the GAO Report, CED-78-128 [2], as part of a question

dealing with "advantages frequently attributed to conversion with the

metric system, " stated:

"Conversion will provide an opportunity for implementing or expanding 'dimensional or modular coordination' ," defined in footnote

three as "A direct relationship between the dimensions selected for

54
the design of a building and the sizes of components used in its

construction. Product sizes and dimensions are based on agreed-upon

rules that permit a better fit of products during the building process. Dimensions and sizes are based on a module, such as 4 inches

or 100 millimeters."

Four response categories were used in Question 14: 1. Agree; 2. Disagree; 3. Does not apply; and, 4. No basis to judge. The following

percentage responses are shown on page 16-27, of the report.

Overall Responses

Group of Agree Disagree Does not No basis

Respondents apply to judge

All Associations 38% 13% 7% 42%

Designers 39% 12% 15% 33%

Contractors 44% 7% 9% 41%

Labor 44% 11% 44%

Manufacturers 32% 18% 8% 43%

Distributors 42% 5% 53%

Codes & Standards 60% 40%

Real Estate 22% 11% 6% 61%

It is interesting to note that, if one considers only the definite

responses "agree" or "disagree," nearly three-quarters (74.5 percent) of

all associations concurred with the question asked, ranging from 64 percent of manufacturers to 100 percent of codes and standards. However,

it is also significant that almost half of the respondents (49 percent)

selected the neutral choices "does not apply" or "no basis to judge."

In the latter category the range is from 33 percent of designers to

61 percent of real estate.

All in all, the definite responses to the GAO Study reinforce the

previous findings and statements by many leaders of the construction

community that "metrication would be an opportunity for implementing or expanding dimensional or modular coordination in building."

4. 4 The Metric Building Module Compared with the Traditional 4-Inch

Module

The advantages of metric dimensional coordination in building are derived

to a large extent from the mathematical and technical features of the

metric building module of 100 mm, which represents one decimal part of

the meter. This dimension is only 1/16" (or 1.6 mm) smaller than the

traditional 4-inch module, which has been widely used in the sizing of

building products and design approaches in the U.S. construction

industry. Therefore, metric modular dimensions and sizes would differ

i 55
only slightly—they would be 1.6 percent smaller and, in many instances,

remain within existing tolerances. The principal advantages of the

metric module are outlined below.

4.4.1 Metric Modular Dimensions are Directly Visible . Any dimension,

in millimeters, with two zeros (00) at the end is always a modular dimension, that is, a whole multiple of the 100 mm module. But much more significant in the design and construction context, is that the "modular

multiplier" is directly visible and represented by the number in front

of the two zeros. This makes it possible to identify and select "preferred" multimodular values at a glance. For example, although 4700 mm

is a modular dimension it can be recognized instantly as a less preferred

multiple because the multiplier, 47, is a prime number and divisible only

by itself and one. By comparison, 4800 mm, or 48 modules, has superior

properties of divisibility—it is a whole multiple of the following

"modular dimensions:" 2400, 1600, 1200, 800, 600, 400, 300, and 200 mm. Thus, when a choice is available, the designer and contractor would

almost invariably be better off with 4800 mm.

In the customary context, multimodular dimensions are partly "hidden"

by the need to use both feet and inches in stating them. For example,

a dimension of 15 '-8" can readily be recognized as a "modular" dimension,

that is, divisible by 4 inches, but after a little mental arithmetic it

becomes clear that the multiplier is a less preferred 47!

In another example, the foot-inch equivalent of 64 modules is 21 '-4",

which is not immediately recognizable as a whole multiple of 8" and

16", so common in standard product sizes and spacing of structural

members. Quite a few designers, without thinking, might prefer 21'-0"

or 22'-0" for building spaces or spans. There would be no such difficulty with 6400 mm, the equivalent of 64 metric modules, which can immediately be distinguished for its divisibility by 3200, 1600, 800,

400, and 200 mm!

4.4.2 The Modular Square —A Useful Aid in Calculations . The modular

square of 100 mm x 100 mm, which provides the basic two-dimensional

grid, has an area of exac tly 0.01 m

2

( one hundredth of a square meter).

This relationship is very useful in all forms of calculations involving

area, such as in functional properties (structural, thermal, acoustic,

etc.). A "modular" area in metric units simply is the product of the

two multipliers; for example, a door of 800 mm x 2200 mm has an area of

176 modular squares (8 x 22), which can be converted directly to square

meters by dividing by 100, so that it would represent an area of 1.76 m.

If the door had been 2000 mm (or 20 modules) high, the calculation could

have been done in the mind. By comparison, a modular square with 4"

sides represents l/9th of a square foot or l/81st of a square yard, so that calculations are much more awkward. A customary door of 2' -8" x

7 '-4", which has 176 customary modular squares, requires a lengthy calculation and rounding to establish its area, because there are no decimal

relationships.

56
The direct relationship between the metric modular square and the square

meter (m2

) becomes even more significant in calculating costs of buildings, building elements, or building components, where any cost in $/m2

has the same numerical value in cents per square module. For example,

a cost of $6/m2 also represents a cost of 6<t per square module. This

enables more accurate costing of modular buildings and modular building

products, as well as tighter cost control. In computerized building

design and documentation, the cost of design alternatives could be factored into the decision process without much difficulty as part of metric

modular coordination.

4.4.3 The Modular Cube . The modular cube of 100 mm x 100 mm x 100 mm,

which is the basic unit in a three-dimensional modular space grid, represents a volume of exac tly 0.001 m

3

( one thousandth of a cubic meter) and

a capcity of 1 L (one liter). This relationship greatly simplifies all

calculations involving volume or capacity, such as room or building

volumes, cut and fill computations, HVAC design, and load estimates based

on mass per unit volume of materials. The capacity as well as mass of

the contents of rectangular storage tanks with modular dimensions can be

calculated with ease, based on direct unit relationships that can be

traced right back to the original concepts of the metric system of the

1790's. The units of volume, capacity, and mass were related on a one- to-one basis in the following sequence: 1 cubic decimeter (now a cubic

module, as well) equals 1 liter, 1 liter of water at its maximum density

has a mass of 1 kilogram. This relationship is still very useful; for

example, if the specific gravity of a material is known, the numerical

value also indicates the mass of a modular cube of that material. In

unreinforced concrete with a specific gravity of 2.3 (or a mass density

of 2300 kg/m3

) a modular cube would have a mass of 2.3 kg; in steel,

with a specific gravity of 7.85 (mass density of 7850 kg/m-*) it would

be 7.85; etc.

4.4.4 An Example of Calculations with Modular Dimensions . A practical

example will illustrate the advantages of these relationships in a metric modular concept. A reinforced, precast concrete panel of 100 mm

thickness, 1200 mm width, and 3200 mm height, with a specific gravity

of 2.4 would have the following dimensional and related properties:

Area: 12[00] x 32[00] = 384 square modules = 3.84 m

2 Volume: 1[00] x 12[00] x 32[00] = 384 cubic modules = 0.384 m

3 Mass: 1 x 12 x 32 x 2.4 = 921.6 kg

Force: [mass x 9.8 m/s 2

] = 921.6 x 9.8 = 9032 N = 9.032 kN

Thus area can be computed easily for functional properties or costing;

volume for quantity of concrete required; mass for transportation of

the panel; and force for lifting and structural load calculations.

4.4.5 Metric Drawing Scales and the Building Module . Because of the

decimal relationships that extend right through metric measurement applications, the 100 mm building module has two other major advantages in

measurement: it is represented directly as a scalar division on all

57
drawing scales from 1:1 (full size) to 1:100; and it represents a major,

marked graduation on construction tapes.

The scale instruments (hand scales or machine scales) prominently

identify 100 mm and its multiples for ratios from 1:1 to 1:10, as shown

in figure 4-1, and show a major graduation line for 100 mm on the 1:20

scale, where every multiple of 200 mm is marked. At scales of 1:50 and

1:100, the 100 mm building module is represented by 2 mm and 1 mm, re- spectively. Therefore, the designer working on detail drawings is con- stantly reminded of the "modular" dimension as a preferred value. This

is not so in customary scales, which emphasize the foot (3 modules) and

often the 6" and 3" subdivision, rather than the 4-inch module.

Figure 4-1: Examples of Drawing Scales with Modular Dimensions Emphasized

1:1 0 10 mm 20 30 40 SO 60 70 80 90 100 110 120

ililjiii

1 1 1 1 i ! 1 1 1

!M!|!ll!|!lll|lil!

1 2 0 20 mm 40 60 8 0 100

i 120 140 160 180 200 220 240

1 5 o 100 mm 200 300 400 500 600

T f f T f \r T T T

1:10 )

Nil Nil 1

100 mm 200 m S>00 600 7 10 800 900 1000 1100 1200

TTTT TTTTVTTT TTV TTTTVTTVTT

1 20 200 mm 400 d<J<j 900 1000 1200 1400 1600 1800 2000 2200 2400

T The triangles have been added to point to locations of whole multiples

of the 100 mm module on detail scales. They give a direct indication

of the scale factor and the subdivision of the scale; for example;

each mm represents an increment of 1 mm at 1:1; 2 mm at 1:2; 5 mm at

1:5; 10 mm at 1:10; and 20 mm at 1:20.

58
Construction steel tapes for use in building layout and measurement of

building products are the principal measuring instruments on-site. U.S.

customary tapes are graduated in feet, inches, and fractions. Many tapes

also show a special marking for all multiples of 16 inches to facilitate

layout at 16 inch centers. However, modular increments of 4 inches are not marked in any special way, except for multiples of three modules (12" or 1') and four modules (16") on some tapes.

Metric construction tapes are graduated in millimeters for short tapes,

and meters and millimeters for longer tapes. Major graduations occur

every 100 mm (or 0.1 m), thus emphasizing the metric building module at

every increment. Other numbered graduation marks occur every 10 mm. These tapes greatly facilitate modular building layout on-site.

Sections of customary (foot-inch) tapes and metric (meter-millimeter)

tapes are shown in figure 4-2.

Figure 4-2: Customary (Foot-Inch) and Metric Construction Steel Tapes

Section of 12-ft pocket steel tape graduated in feet, inches, and

sixteenths of an inch

Jiiiiil

1 1 1 1

>

LlLlLlLU

H|l|!|ip

iiLjiiiJiiiiiJii.11 111 L 1.

i|imiii|i|i|[

1 3

Li LULL 11 ilihluihhh

in

4 O

Mi

b. Section of 3 m pocket steel tape graduated in meters and millimeters

(100, 10. 5 and 1)

1

' | I | I | I | I | I | I | I | I | I | I |

I | I I I | I | I 80 90 900 10 20 30 40 50 60 70 80 90 lm 10 20

' ''^iilii iiliiiiliiiiliiiilmiliiiiliiiiliiiil iii iliiiilmiU I

c. Section of 30 m precision steel tape graduated in meters and

millimeters

4.4.6 Endorsement of the 100 mm Metric Building Module . The 100 mm

metric building module has been endorsed in publications or information

released by major industry organizations in the United States such

as

The American Society for Testing and Materials (ASTM)

The American Institute of Architects (AIA)

59
The ANMC Construction Industries Coordinating Committee (ANMC/CICC)

and its Sector Committees

The National Association of Home Builders (NAHB)

In addition, as outlined in Part 2, a number of major associations or societies have developed metric policy statements or guidelines which

recommend the conversion to preferred metric dimensions and sizes —

hard conversion—rather than the use of metric equivalents for customary

dimensions or sizes —a soft conversion.

4 . 5 The Practical Application of Dimensional Coordination in Building

Dimensional coordination in building represents a voluntary, but

conscious attempt to "rationalize" the dimensions of buildings as well

as the related sizes of building products or components through the use

of a common unit of size—or module—and selected multiples. Like metrication, dimensional coordination is a matter for cooperative effort

rather than mandate. The establishment of a successful program requires

the cooperation of designers, manufacturers, and many other parties to

the building process, to set down general rules and conventions for the use of preferred dimensions, including guidelines for joints, tolerances,

and limits of fit.

Basically, there are few differences in the stated "aims, principles,

or practical application" of dimensional coordination based on a 4-inch

module, and dimensional coordination based on a 100 mm module. In the

latter case, international recommendations and guidelines have been

established, but the resulting conventions could be used with either

module.

Recent trends worldwide indicate overwhelming support for the 100 mm

module and the derived sizes, and many of the developing nations have

chosen to adopt the content of ISO standards, in full or with minor variations, as their national standards. The trends also show a move away

from the rigid application of modular grids as the basis for coordination, and the substitution of a few major "controlling planes or lines"

instead. The distances between such controlling planes are called "controlling dimensions," and these are normally selected from preferred

multiples of the building module.

On plan, such controlling dimensions can occur in two ways. They may

either be taken between the "coordinating (or nominal) faces" of building elements, in which case they are referred to as boundary controlling

planes, or they may be taken from axis to axis of structural elements,

in which case they are referred to as axial controlling planes. Either

approach has advantages. Normally, boundary control is more useful in

buildings with many structural elements and subdivision into small spaces,

for example in most residential type structures. Axial control, generally, is more appropriate in larger buildings or structures, with long

spans and open plans, such as industrial type structures.

60
The alternative approaches are Illustrated graphically in figures 4-3

and 4-4.

Figure 4-3: Boundary Controlling Figure 4-4: Axial Controlling

Planes Planes

Preferred dimensions for horizontal control have been established in ISO

standards, and dimensions which are whole multiples of 300 mm, 600 mm,

1200 mm, 3000 mm, and 6000 mm are most favored, with a limited application of 1500 mm as an additional preference. The absence of U.S. representation in ISO has meant that the typical U.S. preference for four

modules (or 400 mm) traditionally used in spans, spacings, and many

product sizes (16" increments) is not included, except in the multiples

1200 mm and 6000 mm.

In section, controlling dimensions occur between controlling planes at

floor level, ceiling level, and roof level. They are generally referred

to as floor-to-floor height (story height), floor-to-ceiling height (room

height), ceiling-to-roof height, or floor-to-roof height, as appropriate.

Multiples of 100 mm, 300 mm, and 600 mm have been suggested as preferred

dimensions for vertical control in international proposals, with the use

of such increments specified for particular ranges of dimensions. The

typical U.S. preference for two modules (or 200 mm) traditionally used in

masonry products (8" vertical control), is not specifically mentioned.

Additional intermediate controlling planes occur at door head and window

head height, and at window sill level. These dimensions identify the

vertical component of preferred opening sizes.

Vertical controlling dimensions and intermediate controlling planes are shown in figures 4-5 and 4-6.

61
Figure 4-5: Vertical Controlling Figure 4-6: Intermediate

Dimensions Controlling Planes

A further refinement is the designation of supplementary spaces, or "zones," to accommodate structural elements and non-usable space. These

zones may be modular (controlling zones) or non-modular (neutral zones).

4. 6 The Choice of Preferred Dimensions

The principal aspect of dimensional coordination in building is the

selection, by industry consensus, of "preferred" dimensions for the

design coordination of buildings, and the sizing of building products.

With careful choices and cooperation between all major groups affected,

much greater "dimensional harmony" is feasible than is known today

without any sacrifice of flexibility. Customary sizes were developed in

response to needs at particular points in time either unilaterally or by consensus. Many traditional product sizes are compatible with modular

coordination, and the similarity in customary and metric modules should

make it possible to continue production in the same facility and with

the same equipment, albeit modified in some instances.

What then are preferred dimensions? As construction is an additive

process, any dimension which can be further divided into whole modular

62
subunits is definitely preferred. This is where multipliers such as 6 (divisible by 1, 2, and 3); 12 (divisible by 1, 2, 3, 4, and 6); and 60

(divisible by 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, and 30) have decided

advantages. In a metric modular context, dimensions such as 600 mm

(6 modules), 1200 mm (12 modules), and 6000 mm (60 modules) have long

been recognized as preferences, independently of their close similarity

to customary dimensions of 2 feet (6 modules), 4 feet (12 modules),

and 20 feet (60 modules).

In fact, metric preferences combine the benefits of decimalization, in

the form of a 100 mm basic module, with highly divisible numbers, and,

therefore, would provide some additional benefits. This is easily illustrated by a comparison of the customary modular dimension of four feet

(equal to 48 inches, or 12 modules) and the metric counterpart of 1200 mm

(12 metric modules). Table 4-1 lists divisibility into whole subunits,

in modular as well as non-modular sizes. "Modular divisibility" remains

the same, while non-modular divisibility is increased significantly. The

non-modular sizes can be used for small additive components, such as tile, brick, etc., which are used in combination, for example, in mosaic

patterns

.

Table 4-1: Comparison of Divisibility

Divisor

4'-0" [12 modules] 1200 mm [12 modules]

Modular Size

Non-modular

Size Modular Size

Non-modular

Size

1 4'-0" 1200 mm

2 2'-0" 600 mm

3 l'_4" 400 mm

4 l'-0" 300 mm

5 240 mm

6 8" 200 mm

8 6" 150 mm

10 120 mm

12 4" 100 mm

15 80 mm

16 3" 75 mm

20 60 mm

24 2"* 50 mm*

25 48 mm

32 lh"

40 30 mm

48 1"* 25 mm*

50 24 mm

Total 6 5 6 12

* indicates a submodule

Similar comparisons may be made for each "pair" of customary and metric

modules.

63
4. 7 Issues in Production ~ Sizes of Modular Building Products and

Components

The manufacturing industry is unlikely to produce metric modular products

until a demand emerges. Such a demand is unlikely to develop before a construction industry M-Day, and may only build up slowly after that, as contracts for metric buildings are let. Initially, some metric modular

products are likely to enter the market as additional product lines, but

a prolonged transition period would probably create more problems for the

manufacturer than the customer as a result of dual inventories. For this reason it is essential that "consensus decisions" be reached throughout

industry—without a commitment the safest course might be to remain with

traditional sizes and to let others hazard "metric experiments."

The lessons from other countries do not bear out predictions of gloom.

They are particularly interesting in a logical approach to the establishment of "industry preferences" for building component and assembly

sizes, based on the 100 mm module and selected multiples.

A "metric preferred size selection matrix" is shown in table 4-2. The

purpose of the matrix, which was also included on page 54 of the AIA

Metric Building and Construction Guide [3], is to facilitate the identification of size preferences in four product categories, ranging from

small components to very large components.

In the sizing of modular products, it must be remembered that "coordinating dimensions" are ideal dimensions, taken from centerline to centerline of adjacent ^components; that is, they include half a joint width on each side. For example, the standard (or specified) size for modular

masonry units with coordinating dimensions of 100 x 100 x 300 mm, would

be one joint width less, or 90 x 90 x 290 mm for the standard 10 mm mortar joint. This is the same as in traditional practice, where a modular

masonry unit of 4" x 4" x 12" with a 3/8" joint would have standard

dimensions of 3-5/8" x 3-5/8" x 11-5/8", except that whole millimeters

are used instead of inches and fractions. Similarly, in the case of

building board or wallboard, the joint width is normally considered

minimal and part of the tolerances allowed for production irregularities,

so that a "coordinating size" of 1200 x 2400 mm (or the customary 4'-0"

x 8'-0") would also be the standard (or specified) size.

Tolerances for metric product sizes will be expressed in millimeters

rather than in fractional units; for example, a ceiling tile might be

shown as 300 x 600 mm, with tolerances of -2 mm, +1 mm, compared with

a customary ceiling tile of 12" x 24", with tolerances of -1/8", +1/16".

(These values are shown only for illustrative purposes.)

64
Table 4-2: Metric Preferred Size Selection Matrix

CATEGORY TYPICAL EXAMPLES OF COMPONENTS AND ASSEMBLIES

DIMENSIONAL PREFERENCE

(mm) First Sec ond A: Small Components

(under 500 mm) Brick, block, tile, paving units

100 200

300 400

2550

75 150

250

B : Med ium- s i z e Components and Assemblies

(under 1500 ram)

Sheets, panels, partition

units, doorsets, windows,

slabs

600

800 900

1200

500

700 1000 1400

*Note 1

Ci Large - size

Components and Assemblies

(up to 3600 mm)

Precast floor unxts, pre- cast wall units, panels, door assemblies, window

assemblies, precast

stairs, precast ducts

1800

2400

3000

3600

(n x 300 ) 1500 2100

2700

3300

(n x 200) 1600

2000

2200

2600

2800

3200

3400

*Note 2

D : Very Large

Components and Assemblies

(over 3600 mm)

Prefabricated building

elements, precast floor

and roof sections,

4800

6000

7200

8400

9600

10 800

12 000

(n x 600) 4200

6600

7800

9000

10 200

11 400

(n x 1500) 4500

7500

10 500

*Note 3

NOTES: 1. For the purposes of rationalization, those multiples of 100 mm, above 1000, which are prime numbers (e.g., 1100, 1300, 1700, 1900, 2300, 2900, eta.) constitute a lower order of preference and should

only be considered where special requirements exist.

2. Alternative second preferences are shown; for vertical dimensions

the use of multiples of 300 nrn, particularly in conjunction with masonry materials.

3. Alternative second preferences are shown; for some projects it will be more appropriate to size large components or assemblies in multiples of 1500 rrm.

4. 8 Construction - The Trade-off Between Design Dimensions and Product

Sizes

Efficient construction involves the positioning and assembly of a variety

of building components from different sources into an organized and functional whole with a minimum of cutting, fitting, or other waste of effort

and materials. Modular construction has long been looked at as a means

of obtaining greater efficiency in construction and, thus, stabilizing

building costs.

Efficient construction, to some extent, depends on the harmony of design

dimensions and building product sizes, as any mismatch requires cutting

and/or fitting of materials. Obviously, some cutting will always be

needed around openings, projections, or corners, but the intelligent use

of preferences can reduce its amount without resulting in stereotypes.

This applies regardless of the measurement system used.

65
However, for reasons discussed earlier, the visibility and divisibility

of metric preferred dimensions would offer opportunities for savings

right through the building design and construction processes. A tradeoff matrix for preferred design dimensions and product sizes was developed in Australia, and has been refined for U.S. use. The matrix is an original "metric decision aid," but it could be duplicated in customary

dimensions, based on the 4-inch module.

The matrix, in table 4-3, shows on the horizontal axis a selection of

dimensional preferences for building products between 100 mm and 1200 mm,

and on the vertical axis design dimensions from 200 mm to 6000 mm. In

the squares of the matrix, where appropriate, divisibility of the design

dimensions is indicated by numerals which show the multiple of preferred

product dimensions. The summary columns list the total divisibility of

modular design dimensions as well as the two non-modular dimensions

included. It gives a very clear indication why, for example, 3600 mm is

a better design dimension than iti, neighbors , 3500 mm and 3700 mm, since

it represents a whole multiple of many different modular product dimensions. All prime number modules, such as 3700 mm, have been shown in

italics to indicate that they offer more limited value in modular coordination. The matrix can be expanded, and readily adapted for computer

design decisions.

4. 9 Modular Drawing Practice

Modular drawing practice has relied heavily on the use of modular grids

to control dimensions, sizes, and position, using either the basic module

or multimodules as grid intervals. Grids are also used in metric dimensional coordination to facilitate precoordination decisions in designs,

but more emphasis is placed on controlling lines, such as floor or ceiling planes, which are shown with a little circle at the end. An open

45-degree arrow replaces solid arrows in the identification of modular

controlling or coordinating dimensions.

4.10 The Development of Standards for Dimensional Coordination in

Building

The United States has the distinction of having had the first national

standards committee on "the coordination of dimensions in building,"

namely Project A62 in the American Standards Association in 1939, which

prepared a series of four national standards based on a 4-inch module,

between 1945 and 1957 [4]. Another burst of modular standards activity

took place after the American Standards Association changed its name

to USA Standards Association and, a little later, to the present name American National Standards Institute (ANSI), with four additional

standards in the A62 series issued between 1968 and 1971 [5],

In 1974, the responsibility for the development of standards dealing

with dimensional coordination was transferred from ANSI to the American

Society for Testing and Materials (ASTM), and a new Subcommittee E.6-62

66
Table 4-3: Matrix of Modular Design Dimensions vs. Modular Product

Sizes to Show Whole Multiples of Product Sizes and the

Extent of Modular Options in the Range 200 mm to 6000 mm

Product Dimensions noou i a

Other

100 150 200 250 30CT 400 500 600 700 800

_ _ - 900 1000 1200 Mul t i pies Mu 1 1 i p 1 es

200 2 1 2

_ 300 3 2 1 2 1 400 4 2 1 3 500 5 2 1 2 1 600 6 4 3 2 1 4 1 700 7 1 2 800 8 4 2 1 4 900 9 6 3 1 3 1000 10 5 4 2 1 4 1 1100 11 1 1200 12 8 6 4 3 2 1 6 1 1300 1

1 1400 14 7 2 3

- 1500 15 10 6 5 3 3 2 1600 16 8 4 2 4 - 1700 17 1 1800 18 12 9 6 3 2 5 1900 19 1 - 2000 20 10 8 5 4 2 5 1 2100 21 14 7 3 3 1 2200 22 11 2

- 2300 23 1 - 2400 24 16 12 8 6 4 3 2 7 1 tDUU 9CL J 1 u 5

9 i 2600 26 13 2

- 2700 27 18 9 3 3 1 2800 28 14 7 4 4 2900 29 1 3000 30 20 15 12 10 6 5 3 6 2 3100 31 1 - 3200 32 16 8 4 4 3300 33 22 11 2 1 3400 34 17 2 - 3500 35 14 7 5 3 1 3600 36 24 18 12 9 6 4 3 7 1 3700 37 1

1 3800 38 19 2

- 3900 39 26 13 2 1 4000 40 20 16 10 8 5

4 6 1 4100 41 1 4200 42 28 21 14 7 6 5 1 4300 43 1 4400 44 22 i i 3 4500 45 30 18 15 9 5 4 2 4600 46 23 2

_ 4700 47 1 4800 48 32 24 16 12 8 6 4 7 1 4900 49 1 2 5000 50 25 20 10 5 4 1 5100 51 34 17 2 1 5200 52 26 13 3 5300 53 1 5400 54 36 27 18 9 6 5 1 5500 55 22 11 2 1 5600 56 28 14 8 7 5 5700 57 38 19 2 1 5800 58 29 2 5900 59 1 6000 60 40 30 24 20 15 12 10 6 5 8 2

67
was formed to deal with "Coordination of Dimensions for Building Materials and Systems," under the jurisdiction of Committee E.6, Performance

of Building Constructions.

To date, ASTM Committee E.6 has issued only one standard, ANSI/ASTM

E577-76, Standard for Dimensional Coordination of Rectilinear Building

Parts and Systems [6]. It uses a novel approach of designating dimensional preferences by the symbol "U" (for unit dimension), and assigning

values to U in both metric (SI) and U.S. customary units. The U represents both 100 mm in metric units and 4 inches in U.S. customary units,

as the standard increment and the standard spacing in a modular grid.

The standard implies that at some future date dimensional coordination

based on a 100 mm module is likely to take over from dimensional coordination based on the 4-inch module, and that the general principles may be

applied regardless of unit choice. But the duality could lead to problems in production and construction, since modular metric products will

not be interchangeable with modular customary products, and vice versa. The standard is under review, and it has been suggested that it should

be replaced by a companion standard in two separate issues, one entirely

in metric units, and the other entirely in U.S. customary units.

ASTM Committee E.6 has under consideration a proposed standard on "Dimensional Coordination of Structural Clay Units, Concrete Masonry

Units, and Clay Flue Linings," as companion standards with separate

metric and customary versions. The ideas advanced in the draft standard

are not new; much of the content is based on material contained in former ASA (ANSI) standards A62. 2-1945; A62. 3-1946, and A62. 4-1947. The

comparison standards are discussed in more detail in 5.3.

REFERENCES

1. International and National Standards on Dimensional Coordination,

Modular Coordination, Tolerances and Joints in Building, NBS

Special Publication 595; National Bureau of Standards, Washington,

D.C. (To be published October 1980).

2. Report to the Congress by the Comptroller General of the United

States, "Getting a Better Understanding of the Metric System

Implications if Adopted by the United States," CED-78-128; 740 pages;

Superintendent of Documents, U.S. Government Printing Office,

Washington, D.C; October 20, 1978; and, Executive Summary

CED-78-128A; 71 pages.

3. AIA Metric Building and Construction Guide; The American Institute

of Architects, Wiley Interscience Inc., New York, NY; 1980; 154 pages.

4. American Standard Basis for the Coordination of Dimensions of

Building Materials and Equipment; A62. 1-1 945 (R1957 ) ; American Standards Association (now ANSI); New York, NY; 1957; 6 pages.

68
American Standard Basis for the Coordination of Masonry; A62. 2-1945;

American Standards Association (ANSI); New York, NY; 1945; 6 pages.

American Standard Sizes of Clay and Concrete Modular Masonry Units;

A62. 3-1946; American Standards Association; (ANSI); New York, NY;

1946; 14 pages.

American Standard Sizes of Clay Flue Linings; A62. 4-1947; American

Standards Association (ANSI); New York, NY; 1947, 7 pages.

USA Standards - Basis for the Horizontal Dimensioning of Coordinated

Building Components and Systems, A62. 5-1968; United States of America

Standards Institute (ANSI); New York, NY; 1968; 8 pages.

American National Standard - Classification for Properties and Performance of Coordinated Building Components and Systems, ANSI A62.6-

1969; American National Standards Institute, New York, NY; 1969;

11 pages.

American National Standard - Basis for the Vertical Dimensioning of

Coordinated Building Components and Systems, A62. 7-1969; American

National Standards Institute, New York, NY; 1969; 11 pages.

American National Standard - Numerical Designation of Modular Grid

Coordinates, A62. 8-1971; American National Standards Institute,

New York, NY; 1971; 13 pages.

Standard for Dimensional Coordination of Rectilinear Building Parts

and Systems, ANSI/ASTM E577-76; American Society for Testing and

Materials, Philadelphia, PA; January 1977; 4 pages (This is currently

subject to review.

)

69

PART 5 - PROPERTIES AND SIZES OF METRIC BUILDING PRODUCTS—PRECEDENT,

CHANGES PROPOSED, AND CHANGES MADE

5 . 1 Metrication and Building Products - Some General Observations

A change to metric (SI) units in construction would require the review

of the dimensions and physical properties of most building materials,

components, and assemblies. Before selecting new sizes, it would be

desirable to assess the impact of metrication, difficulties associated

with the change-over, opportunities for rationalization and variety

reduction, and alternative strategies for conversion.

Initially, many products would require no change other than their

description in metric terms and/or adjustment within existing production

tolerances. This metric veneer is termed a

" soft conversion " to equivalent metric values within tolerances, since the only changes that

would be made would occur on paper—in the software. Where dual labeling is used, it would not even be necessary to keep separate inventories.

In a soft conversion, a manufacturer would seek out "convenient" numerical values, rather than preferred metric values; for example a 12 inch

length (304.8 mm) would simply be shown as 305 mm. Generally, a soft

conversion allows producers to postpone changes to new and preferred

sizes or properties until the next redesign or new product development.

On the other hand, to take advantage of "preferred metric dimensions or sizes," other products would require a

" hard conversion ," that is, a change to new and non-interchangeable sizes, to fit in with industry

preferences or to reduce variety. The term "hard conversion" is used

not only because such a change is often more difficult, but because the

hardware is changed so that separate inventories would have to be kept.

A typical hard conversion would involve a change from multiples of 4 inches

(101.6 mm) to multiples of 100 mm; for example, a 12 inch (304.8 mm) com- ponent would be replaced by a 100 mm component.

Metric changes could be attempted one-at-a- time , or simultaneously,

with all changes to a product occurring at the same time. In the first

case, the costs may be spread over a greater period of time; however,

it could require successive revision of technical data, which may

reduce its cost-effectiveness.

The principal theme associated with change should be "rationalization

through metrication." This means that product ranges should be reviewed

for functional and economic efficiency, for example, whether the range

carried presents an optimum range, or whether the steps within a range

are really the best or only exist because of tradition and historical

factors. A change to metric products could lend itself to the pruning of

products that have been liabilities, either as a result of long shelflife and slow sales, or poor contribution to profit. In some instances,

product lines could be reduced without costs to the producer, designer,

71
or user, but with gains to the producer, distributor, or contractor.

Some examples are discussed in the assessment of specific product

groups

.

Metric production considerations are discussed in Section 4, of NBS

Special Publication 530 [1], dealing with "Managerial and Economic

Considerations in the Change to a Metric Production Environment." Guidance on conversion strategies and the selection of convenient and preferred metric values is given in NBS Technical Note 990, "The Selection

of Preferred Metric Values for Design and Construction" [2],

5 . 2 International Precedent as a Guide

Although the U.S. construction community has a larger turnover than

that of any other country, the precedent of metric production decisions

from other countries offers many useful suggestions of how to adapt to

metric with a minimum of cost and disruption, and of the pitfalls that

should be avoided.

Precedent from Britain, South Africa, New Zealand and Australia is

already dated by time, and many of the people who made the decisions or managed the resulting changes have already retired. In any case, Canadian precedent is the most relevant guide, because of the many similarities in construction technology and practices, joint participation in

standards development activities, interlocking industrial ownerships in

many segments of industry, as well as a general exchange of technological ideas and research findings. In addition, Canada is geographically

closest and is now in the transitional stages of metric conversion in

the construction industries—the Canadian M-Day for construction was on January 1, 1978—so that it presents an ideal learning model for the

United States. While it has been suggested that, due to the much larger

U.S. economy, metric adaptation costs and problems would be greater

than elsewhere, (in the case of the concrete block industry the relative

size of Canada and the United States has been used as a factor in cost

estimates). These predictions of cost have tended to ignore three

aspects that would facilitate a change in the United States:

1. A larger economy allows a "progressive change" with manufacturers

changing when it is economically most advantageous, and not all at

the same time. As metric demand builds up, more and more organizations would change.

2. Lead-times now available allow for optimum planning of equipment

obsolescence and replacement decisions.

3. With variety reduction, larger and longer production runs are possible, which would reduce unit costs.

In the discussion of metric progress and proposals in various industry

segments, Canadian precedent will serve as an illustration of "metric

72
trailblazing , " particularly as Canadian industry is now producing products

based on joint United States/Canada proposals.

5.3 Metrication and Masonry Products

Masonry units, made from fired clay or concrete, have traditionally been

of modular sizes. The masonry products industry has not taken a definitive stand on metric dimensions and sizes, but some masonry industry

leaders see the value of metric masonry products as a backbone in metric

dimensional coordination. As in other countries that have converted,

metric masonry unit sizes would probably be determined early on and be

available when needed. Early predictions of greater costs associated

with the change have not materialized in other countries, because the

available lead-time was used to minimize costs by taking advantage of

planning obsolescence in production machinery, and normal replacement

cycles for extrusion dies and molds. Also, some products now produced

are within tolerances of metric sizes, such as the 7-1/2" brick.

As noted in 4.10, the American Society for Testing and Materials (ASTM)

Committee E.6 is in the process of developing a standard for "Dimensional Coordination of Structural Clay Units, Concrete Masonry Units,

and Clay Flue Linings," to be issued in two non-interchangeable com- panion documents, one in SI units and the other in U.S. customary units.

The metric version will have preferred dimensions based on the 100 mm

module. A significant difference is that the metric standard proposes

only two standard joint thicknesses, 10 mm and 5 mm, compared with three

standard joint thicknesses in customary units (1/2", 3/8", and 1/4"),

for brick and facing tile, thus reducing variety in design detailing and

production.

5.4 Metriciation and Building Lumber

The lumber and wood products industry has studied metric issues for the

past five years as part of the work of the ANMC Lumber and Wood Products

Sector Committee and its ten Subsectors. The industry has relaxed its

early activities based on the assumption that most issues have been

resolved and that there is no great pressure for conversion within the

industry or on the industry. A general statement of the industry's

metric position in mid-1978 is contained in "Lumber and Wood Products

Metric Planning Package" [3], issued by the National Forest Products

Association.

On page 4, the document proposes a soft conversion of existing widths

and thicknesses of softwood building lumber, with marginal rounding down

in the larger sizes. (Tables 1-5, pages 12-16.) Widths and thicknesses

will be designated in millimeters (mm) and in net dimensions rather than

current nominal sizes. Lengths will be hard converted in multiples of

600 mm, coordinated with proposed building dimensions based on the 100 mm module and proposed metric sizes of panel products.

73
In marketing and costing, lengths will be shown in meters (m) . The

proposed sizes would probably be reevaluated during and after an actual

conversion, when both producers and users realize that greater rationalization is possible with preferred sizes that suit the needs of the

industry, and facilitate the design and construction processes.

5.5 Metrication and Concrete

The concrete industry would likely be a lead sector in any metrication

effort as it has been in other countries that have made the change.

Modifications necessitated by the change to SI are not extensive, but

the potential for variety reduction and rationalization is considerable.

5.5.1 Bulk Materials for Use in Concrete . Constituent materials used

in the manufacture of concrete would not represent major problems in a change to metric (SI) units. Sand and aggregates could be delivered by

the metric ton (t) instead of the U.S. short ton. Where volume is preferred, such as in paving, the cubic meter (m3

) could replace the cubic

yard (yd-*) and cubic foot (ft 3 ). Water could be measured in terms of

liters [L] instead of U.S. gallons. As mentioned earlier, the relationship of the liter cube and kilogram, and their derivation from the cubic

meter (1 L = 0.001 m3

; 1 L of water at S.G. of 1.0 = 1 kg) would facilitate mix and placement calculations. Cement is a powder and would not

require any modifications in the manufacturing process. However, bulk

cement could be sold by the metric ton (t), while bagged cement would

probably be shipped in 40 kg bags (25 bags per metric ton), replacing

the current 94 lb. bag (42.6 kg).

5.5.2 Ready Mixed ^Concrete . Ready mixed concrete could be delivered by

the cubic meter (m 3 ), approximately 1.3 cubic yards, but increment steps

for orders could be a matter for local determination within broad overall

guidelines. Concrete strength grades could be expressed in megapascals

(MPa) instead of psi, in a regular progression with fewer steps than at

present. It is likely that 5 MPa steps would be used, such as: 15 MPa

(2175 psi); 20 MPa (2900 psi); 25 MPa (3625 psi); 30 MPa (4350 psi); 35 MPa

(5075 psi); and 40 MPa (5800 psi). For higher strengths, increments of

10 MPa would likely be preferred.

5.5.3 Concrete Reinforcing Steel . A change to metric (SI) units would

present an opportunity for the review and rationalization of reinforcing

steel sizes and ranges. This fact is well recognized by the Concrete

Reinforcing Steel Institute (CRSI), which has been involved in detailed

studies and discussions with Canada to bring about a new and rationalized

range of reinforcement in North America.

Proposals are based on preferred sizes derived from the principal design

criterion, cross-sectional area, and the use of sizes in select multiplies

of 100 nmS The metric sizes, which are the subject of a standby standard

prepared within ASTM, are already in use in Canada. They involve a reduction in range from the 11 current sizes to 8 metric sizes, and, therefore

simplification of production, distribution, fabrication, and design

74
activities. Five of the eight new sizes are within weight tolerances of

existing bars, which means that roll changes are needed for only three

bar sizes.

Two Canadian standards provide details of the geometrical and other

properties of the new range: CSA Standard G30 . 12-Ml 977 , Billet-Steel

Bars for Concrete Reinforcement [4]; and, CSA Standard G30. 16-111977

,

Weldable Low Alloy Steel Deformed Bars for Concrete Reinforcement [5].

Table 1 in both standards is identical and has been reproduced for

information:

Table 1 Deformed Bar Designation Numbers', Nominal

Dimensions 7

, Unit Masses, and Deformation Requirements

Nominal Dimensions Deformation Requirements mm

Mass

Cross- (Weight) Maximum Gap

Bar Sectional Per Unit Maximum Minimum Chord of 12 5 Designation Area Diameter Perimeter Length Average Average Per Cent ot Number mm3 mm mm kg/m Spacing Height Nominal Perimeter 10 100 11.3 35.5 ,0.785 7.9 0.45 4.4 15 200 16.0 50.1 1.570 11.2 0.72 6.3 20 300 19.5 61.3 2.355 13.6 0.98 7.7 25 500 25.2 79.2 3.925 17.6 1.26 9.9 30 700 29.9 93.9 5.495 20.9 1.48 11.7 35 1000 35.7 112.2 7.850 25.0 1.79 14.0 45 1500 43.7 137.3 11.775 30.6 2.20 17.2 55 ' 2500 56.4 177.2 19.625 39.4 2.55 22.2

* Bar numbers are based on the number of millimetres included in the nominal diameter of the bars.

t The nominal dimensions of a deformed bar are equivalent to those of a

plain round bar having the same mass per metre as the deformed bar.

The cross-sectional areas for conventional bars [#3 to #18] are given

for comparison purposes and metric replacements are shown below:

Customary

Designation

Area in mm2

#3

71

#4

129

#5

200

#6

284

#7

387

#8

Metric Area/

Designation 100 200 300

510

500

I #9

645

#10

819

#11

1006

#14

1452

#18

2581

700 1000 1500 2500

The 100 mra^ rebar replaces both #3 and #4; the 700 rara^ rebar replaces

both #9 and #10. Only #7 (7/8" <f>) has no metric equivalent, and its use should be limited as the transition period approaches to avoid the

possibility of non-availability after a change is implemented. Some

buildings may be built during the change from one range to another,

and foreknowledge of metric proposals will minimize adaptation problems.

75
5.5.4 Precast and Manufactured Concrete Products . While in-situ concrete

construction in metric units would be a matter of fairly simple dimensional

adaptation by setting formwork to metric spans, spacings, or other design

dimensions, manufactured concrete products made in forms or on casting

beds to foot-inch dimensions could present more adjustment problems.

For example, prestressed structural sections, such as T-beams or double

T-beams, could be produced to metric preferred lengths without much

difficulty; however, nominal width preferences would require a definite

change from foot-inch width to metric widths. In the case of a typical

section with a coordinating width of 8'-0", a change to a metric width

of 2400 mm would require a reduction of 1-1/2" (or 38 mm) overall, or 3/4" (19 mm) on each side. This might be accomplished by the insertion

of a 3/4" filler piece on each side, if the sides of the form are not

adjustable. Otherwise, the profile would probably remain unaltered

until the form is replaced, renewed, or possibly superseded by a new design in metric preferred dimensions.

Lead-times available now could be well used by identifying lifecycles

of casting forms, potential new designs, and alternative adaptation

strategies to enable a cost-effective adjustment to a metric building

environment

5.5.5 Concrete Design Data and Technical Information . The American

Concrete Institute (ACI) and the Prestressed Concrete Institute (PCI)

have endorsed metrication, based on an orderly and planned approach. In

view of their international constituencies, both institutes are actively

engaged in developing a metric technical data bank for concrete and concrete products. ACI has an active Board Committee on Metrication, and

has an Institute policy to develop a hard metric version of the key

technical document prepared by Committee 318, "Building Code Requirements

for Reinforced Concrete" [6], by 1983, with the parallel publication of

related standards by that time.

5. 6 Metrication and Metal Products

5.6.1 Structural Steel Sections . The principal ANSI/ASTM standard for

structural steel products, A6- "Standard Specification for General

Requirements for Rolled Steel Plates, Shapes, Sheet Piling, and Bars for

Structural Use" [7], contains metric equivalents and metric dimensions

and properties for standard shape profiles in the Annex. A more extensive listing of properties is contained in the Canadian standard CAN3-

G312.3-M78, "Preferred Metric Dimensions for Structural Steel W and HP

Shapes, Angles, and Hollow Structural Steel Sections" [8].

Whereas the Canadian Standard uses the same sizes and designations for

W and HP Shapes, equal leg angles and unequal leg angles have been

rationalized in metric dimensions and thicknesses, as tabulated below.

76
CAN3 - G312.3-M78 , Table 3 CAN3 - G312.3-M78, Table 4

Equal Leg Angles [Metric]

Thickness (mm)

Unequal Leg Angles [Metric]

Thickness (mm)

Size Size

( mm) J H J o

Qo XU 1 J ID lU Z.J JU (mm )

r>J

A j t

Qo 1

i nu I J ID ZU

Z. JXZ J X X X H JX J U X X X X

J JXJ J X X X X J jxju X X X X

H JX4 J X X X X X aD JXJU w^n X X X X

J JXJ J X X X X X X / JXJU X X X 65x65 X X X X 80x60 X X X X

7 5x75 X X X X X 90x65 X X X X

90x90 X X X X 90x7 5 X X X X X 100x100 X X XXX 100x75 X X X X

125x125 X XXX 100x90 X X X X 150x150 X X X X 125x75 X X X X 200x200 X X X X X X 125x90 X X X X

150x100 X X X X

200x100 X X X X

200x150 X X X

Total Range 50 Total Range: 56

The steel industry has identified metrication as an opportune time to

make some changes and to rationalize product lines for more efficient

operations. For example, the 43 sizes for steel plates in customary

units have been replaced with 28 metric sizes, a reduction in variety by

35 percent, which will facilitate production, distribution, fabrication,

and design detailing once a transition has been made.

A range of American National Standards [9] and identical Canadian

standards [10] exists which provide guidance on preferred sizes for metric

steel products other than structural shapes and other metal products:

ANSI B32. 3-1977 Preferred Metric Sizes for Flat Metal Products (Corresponding Canadian Standard is

CAN3-G312. 1-75)

ANSI B32. 4-1977 Preferred Metric Sizes for Round, Square

and Hexagon Metal Products (Corresponding

Canadian Standard is CAN3-G312. 2-76)

ANSI B32. 5-1977 Preferred Metric Sizes for Tubular Metal

Products Other Than Pipe

ANSI B32. 6-1977 Preferred Metric Equivalents of Inch Sizes

for Tubular Metal Products Other Than Pipe

77
Most steel standards issued by ASTM now have dual dimensions, and a few

have a separate, hard converted metric version designated by the suffix

"M" after the standard identification number; for example:

ASTM A568M-7 7 Standard Specification for Steel, Carbon

and High Strength Low Alloy Hot Rolled

Sheet and Cold Rolled Sheet — General

Requirements (Metric) [11]

5.6.2 Fasteners . The fasteners industry is on the way to a single

system of international fastener standards. The Industrial Fasteners

Institute (IFI), in Cleveland, Ohio, has conducted extensive studies

into an optimum system of metric mechanical fasteners and fastener

application engineering, and has found that significant economic and

technical benefits can be shared by users and producers of fasteners if

advantage is taken of technical improvement opportunities, more efficient use of materials, and "reduction" in the number of different

parts.

After five years of research and technical investigation, as well as liaison with ISO technical committees, the Industrial Fasteners Institute published a series of "Metric Fasteners Standards" [12] in 1976,

which provided for significant product rationalization. Screw threads were based on the ISO basic thread profile shown in Figure 5-1, and the

standards allowed for only one series of diameter-pitch combinations,

rather than "coarse" and "fine" threads.

Figure 5-1: ISO Basic Thread Profile

r

P (pitch) -— 0 125P

BASIC MAJOR DIAMETER

/ v\

\

60° /// \y z

0.54127P

SCREW THREAD AXIS

V J

78
Of particular interest to engineering and construction may be standards

for bolts, screws, nuts, rivets, and other fasteners. IFI Standard 526

[12] deals with "Metric High Strength Structural Bolts, Nuts and Washers,"

and covers nominal lengths from 45 mm to 300 mm, in the following

increments

45 mm to 100 mm: Incremental lengths of 5 mm

100 mm to 300 mm: Incremental lengths of 10 mm

Nominal bolt sizes are designated by a capital M, followed by the

nominal body diameter (e.g., M20 for 20 mm) and an indication of thread

pitch in millimeters (e.g., 2.5 for 2.5 mm). The following combinations

are listed:

45 and 55 mm:

55 and 60 mm:

65 and 70 mm:

70 and 75 mm:

70 to 300 mm:

Ml 6x2

Ml 6x2, M20x2.5

Ml 6x2, M20x2.5, M24x3

Ml 6x2, M20x2.5, M24x3, M30x3.5

M16x2, M20x2.5, M24x3, M30x3.5, M36x4

This abbreviated listing is indicative of the simplicity of the metric

range

.

The IFI Metric Fastener Standards are in the process of being revised,

and a new edition is anticipated in the first quarter of 1981. Some

modifications have been made to bring the entire metric fastener system

into line with ISO standards.

Metric fasteners are being used widely in industrial applications,

particularly in the automotive industry.

5.6.3 Steel Tubes and Pipes . It is likely that most steel tube and

pipe products will initially be "soft converted" to equivalent metric

sizes

.

However, the Tube and Steel Company of America [Tascoa] , of New York,

indicated in a May 1980 new release [13], that the company is leading

the way to metric sizes and that hard metric sizes are available for

the following tubing:

Squares Rectangles

30 mm x 30 mm

40 mm x 40 mm

50 mm x 50 mm

60 mm x 60 mm

100 mm x 100 mm

120 mm x 120 mm

125 mm x 125 mm

25 mm x 50 mm

40 mm x 80 mm

50 mm x 100 mm

60 mm x 120 mm

80 mm x 140 mm

100 mm x 180 mm

150 mm x 200 mm

The release further stated that additional sizes of 150 mm x 150 mm and

175 mm x 175 mm would be added to the range, and that with the planned

79
addition of a new mill in April 1981, production capability of "hard

metric sizes would be increased.

5.6.4 Other Metals - Aluminum, Brass, Copper, Lead, and Zinc . Planning

for metrication is well advanced in the aluminum industry. Through com- mittees of the Aluminum Association, the industry has been preparing for

metric conversion for nine years. In 1978, it issued a "hard metric"

version of its basic reference document, "Aluminum Standards and Data"

[14], using logical metric values for long-term use rather than restating

customary values in metric terms by the use of conversion factors.

The Aluminum Company of America (ALCOA) recently published preferred

metric sizes for its aluminum sheet and plate products, in line with

ANSI standards; and details are available through the Aluminum Association, the National Association of Aluminum Distributors, or the American

National Metric Council.

At the national level, the Metals Sector Committee of the ANMC Materials

Coordinating Committee has developed an outline plan and schedules for

the change to SI in the metals industries. Timing of metric production,

generally, is complementary to the recommended construction industries

metric conversion schedule.

5.7 Glass Products

A change to metric (SI) units would permit some dimensional rationalization of glass thicknesses, with metric designations given in millimeters

(mm) and whole numbers rather than fractions. A system of permissible

tolerances on thickness would mean that some of the existing glass

thicknesses would be fully interchangeable with new metric thicknesses.

Additionally, tolerances for length and width of cut sizes have been

related to glass thickness, so that a metric accuracy system could

likely lead to better fit and functional performance of glazed elements.

The standards adopted by the Canadian glass industry [15] provide a good

guide to the direction in which the metric change could head, especially

as one of the principal glass suppliers in Canada, PPG Industries Canada

Ltd., is affiliated with PPG Industries in the United States. The

principal metric standards include:

CAN2-12. 1-M79

CAN2-12.2-M76

CAN2-12.3-M76

CAN2-12.4-M76

CAN2-12.8-M76

CAN2-12.9-M76

Glass, Safety; Tempered

Glass, Sheet or Laminated; Flat, Clear

Glass, Polished Plate or Float; Flat, Clear

Glass, Heat Absorbing

Glass, Insulating Glass Units

Glass, Spandrel

CAN2-12. 10-M76 Glass, Light and Heat Reflecting for Building

Construction

80
CAN2-12. 11-M76 Glass, Wired; Safety

CAN2-12.12-M79 Glass Sheets, Plastic, Safety

GAN2-12. 13-M79 Glass, Patterned

The principal dimensional standards for sheet or laminated, polished

plate or float, insulating glass units, and spandrel glass are shown

in table 5-1.

Table 5-1. Principal Dimensional Standards--Glass Products

Nominal Thickness Cut Size Canadian National Standard

Thickness Tolerance Length and VJidth CAN2- Series

(mm) (mm) Tolerance (mm) 12. 2M 12. 3M 12. 8M 12. 9M

2 + 0.3 + 2.0 X X

3 + 0.5 + 2.0 X X X X

4 + 0.5 + 2.0 X X X X

5 + 0.5 + 2.0 X X X X

6 + 0.5 + 2.0 X X X X

8 + 0.8 + 2.5 X X X

10 + 1.0 + 2.5 X X X

12 + 1.0 + 3.0 X X X

15 + 1.0 + 4.0 X X

19 + 1.0 + 5.0 X X

22 + 1.0 + 6.0 X

25 + 1.0 + 6.5 X

Wired safety glass comes in 6 mm thickness (+1.5; -0) and 10 mm thickness

(+0.5; -1.5).

5.8 Panels, Sheets, and Tile

Rigid or flexible sheet and tile materials for use on vertical and

horizontal surfaces in buildings are dimensionally significant, inasmuch as they generally bear a relationship to preferred dimensions.

Customary products have nominal sizes related to multiples of feet, or inches, and there is a general fit with the 4-inch building module,

except for floor and wall tile.

As part of a change to metric dimensions, these products probably would

change to whole multiples of millimeters, and, as new products are introduced or product lines rationalized, to metric preferred sizes coinciding

with whole multiples of the 100 mm building module. Some producing

sectors have indicated their recommended preferred sizes. For example,

the metric advisory committee of the American Plywood Association recommends a metric panel size of 1200 x 2400 mm for sheathing grades of

plywood, thus permitting a direct relationship between preferred spacing

of structural members and the sizes of plywood.

81
Concerns have been expressed by segments of the gypsum board industry

that a "hard conversion" to a metric board size of 1200 x 2400 mm would

cause losses in productivity and output, and that a soft conversion of

existing sizes to a metric size of 1200 x 2440 mm (or 1219 x 2438 mm)

would be preferable.

A soft conversion of existing sizes, without any change or changes

within production tolerances, could be an interim solution which may be

supplanted by genuine "hard" metric sizes should building designers

begin to specify such products and contractors demand them for use in

metric building projects. The concern is not new—it was expressed in

Britian, Australia, and Canada—but in each case the industry rapidly

moved to preferred metric sizes as demand for products developed. The

lead-time available now might be used to assess any equipment obsolescence, so that replacement machinery could be introduced to coincide with

a change to metric sizes. In Canada, 1200 x 2400 mm, 1200 x 3000 mm, and

1200 x 3600 mm gypsum wallboard or ceiling panels, and 600 x 2400 mm and

1200 x 2400 mm gypsum sheathing board are now being supplied by Canadian

Gypsum and Westroc Industries.

5 .9 Roofing

Roofing materials include metal decking, shingles, tile, bituminous felts

and a variety of specialized materials and systems made from asbestoscement, fiberglass reinforced polyesters, etc. Dimensional considerations

involve effective cover and overlaps, size and shapes of profiles, and

effective span between supports.

Due to the variety of origins and the relative simplicity of site

modification by cutting or adjustment (of overlap or projection), there

has been no strong dimensional discipline in traditional roofing materials

and systems. A change to modular metric dimensions would permit a reappraisal of approaches and provide an opportunity for rationalization

of sizes, spacings, and overlap.

The first industrial segment of the roofing industry to have assessed

the opportunities of metrication in the wake of the Canadian experience

is the asphalt roofing shingle segment. "Metric shingles," approximately 18 percent larger than customary shingles, are in production in

California (Thagard Oil Company) and in New England (Reynolds Aluminum

Building Products Company), and have gained wide acceptance. The shingles are 1000 mm (39-3/8") (1 meter) long, and 336 mm (13.25") wide, and

are produced on the same manufacturing plant, requiring very little new

equipment. Reports on the production, use, and acceptance of these

shingles are contained in ANMC Metric Reporter issues of March 21, 1980,

and July 1 , 1980 [16]

.

Proposals have also been made in the metal roofing segment to introduce

a metric profile for roll-formed metal decking, with an effective cover width of 1000 mm (39-3/8") to take the place of the traditional width

of 36 inches (915 mm), an effective increase in width of approximately

82
nine percent. The length of metal roof decking represents no major

problem in the longer term, as stock length could be adjusted to suit

metric preferences, and special lengths would be available on large

order quantities in the same manner as now.

5.10 Construction Assemblies - Doors, Windows, Partitions, Skylights,

etc

Composite building assemblies, such as doors (including frames), windows,

partitions, and skylights, could be designed and manufactured to suit

dimensionally coordinated openings in walls or roofs. It is important

to realize that in a metric building environment the size of the opening rather than the size of the product or assembly is regarded as the

critical determinant. The reason, basically, is simple: if products

are manufactured to fit into a standard range of preferred openings,

variety reduction can take place in manufacturing while simultaneously

providing the designer with alternative, though standard, choices. This

approach could lead to better products and containment of construction

costs. Special requirements in prestige buildings or unusual structures

could be catered for as is done now—by individual or batch production

of special assemblies.

A change to metric preferred dimensions could be a unique point in time

at which to reappraise standard details, or to develop standard details

where none exist. If precedent is any guide, the use of a single unit

of measurement—the millimeter (mm) —for the layout of openings, the

manufacture of components, and the specification of tolerances leads

to better accuracy in building.

5.11 Stairways and Built-in Elements

The standardization of floor-to-floor heights (story heights) in buildings

makes it attractive to standardize stair design and detailing, in concrete

as well as steel or wood. This could enable a higher degree of prefabrication, especially as the early availability of stairs on medium or high

rise building projects facilitates construction activities and improves

on-site safety. The use of millimeters for the geometric layout and

detailing of stairs (overall dimensions as well as rise and run) would

facilitate design, manufacture, and construction, and make it possible

to avoid or reduce inaccuracies, especially uneven riser height, and

thus improve stair safety.

Preferred horizontal and vertical dimensions in building facilitates

the integration of large, precast or prefabricated components and elements. Again, the elemental dimensions would be expressed in the same measurement units as the tolerances and clearances for positioning and

fit, thus reducing the likelihood of mismatch. Overall, metric design

and construction could likely lead to neater solutions.

83
5.12 Services Systems; Electrical, Lighting, Air-Conditioning

,

Plumbing, etc.

A transition to "metric" dimensions and configurations in building

services would likely be a slow and gradual one, characterized by rationalization of sizes and ranges wherever practicable. If the industry

determines an M-Day, new product development is almost certain to be

carried out in metric units, and to metric preferences. Electrical

wiring sizes may change following a research evaluation of present sizes

and the potential for optimization to benefit designers, producers, and

users. Plumbing pipes unlikely would require more than a soft conversion

of "nominal" designations, except for the chance to classify all alternatives according to the same principles, possibly internal diameter or cross-sectional area. Air-conditioning ducts may change with new sheet

metal sizes, and some preferred metric duct configurations have been

indicated in American Society of Heating, Refrigerating and AirConditioning Engineers (ASHRAE) documents.

Fixtures, fittings, and accessories could be changed to metric preferred

sizes where this is essential to their "coordination," but need not

otherwise be changed, except when new products are developed. Among the

fixtures and fittings which may require a hard conversion are components

that are integrated into wall or ceiling systems, such as fluorescent

lamps for use in modular buildings, and air-conditioning grilles or diff users.

Considerable investigation has been carried out in the United States and

other countries to arrive at a "metric fluorescent lamp," for use in

metric modular construction, which would be able to use existing ballast

and support systems. A lamp of 1160 mm length has found wide support in

discussions within the International Electrotechnical Commission (IEC).

The IEC is the international standardization body in the field of electricity and electrical applications. (It is noted that the current 4-

foot fluorescent lamp is actually too long for end-to-end mounting of

lighting fixtures in modular construction based on a 4-foot ceiling grid,

so that designers have had to either modify their layout or select a larger ceiling module, such as 4'-l", 4' -1-1/2", or 4' -2".)

REFERENCES

1. Metrication in Building Design, Production, and Construction, NBS

Special Publication 530; National Bureau of Standards, Washington,

D.C.; September 1978; 188 pages.

2. The Selection of Preferred Metric Values for Design and Construction,

NBS Technical Note 990; National Bureau of Standards, Washington,

D.C.; December 1978; 83 pages.

84
3. Lumber and Wood Products Metric Planning Package; The Lumber and

Wood Products Sector Committee; National Forest Products Association;

Washington, D.C.; Mid-1978; 24 pages.

4. Billet-Steel Bars for Concrete Reinforcement, CSA Standard G30-12-

M1977, Canadian Standards Association, Rexdale, Ontario, Canada;

February 1977; 16 pages.

5. Weldable Low Alloy Steel Deformed Bars for Concrete Reinforcement,

CSA Standard G30 . 1 6-M-l 977 ; Canadian Standards Association, Rexdale,

Ontario, Canada; November 1977; 17 pages.

6. Building Code Requirements for Reinforced Concrete, ANSI/ACI 318-77;

American Concrete Institute, Detroit, MI; 1977; 103 pages.

7. Standard Specification for General Requirements for Rolled Steel

Plates, Shapes, Sheet Piling, and Bars for Structural Use, ANSI/ASTM

A6-78 e

, American Society for Testing and Materials, Philadelphia,

PA; January 1980; 62 pages.

8. Preferred Metric Dimensions for Structural Steel W and HP Shapes,

Angles and Hollow Structural Sections, CAN3-G3 1 2 . 3-M78 ; Canadian

Standards Association, Rexdale, Ontario, Canada; November 1978;

28 pages.

9. Preferred Metric Sizes for Flat Metal Products, ANSI B32. 3-1977;

April 1977; 9 pages; and Supplement ANSI B32.3a-1978, August 1978;

1 page.

Preferred Metric Sizes for Round, Square, Rectangle, and Hexagon

Metal products; B32.4M-1980; April 1980; 11 pages.

Preferred Metric Sizes for Tubular Metal Products Other than Pipe,

ANSI B32. 5-1977; September 1977; 8 pages.

Preferred Metric Equivalents of Inch Sizes for Tubular Metal Products

Other than Pipe, ANSI B32. 6-1977; August 1977; 8 pages.

The above four standards available from the American National

Standards Institute, New York, NY.

10. Preferred Metric Dimensions for Flat Metal Products, CAN 03 12 . 1-1 97 5

;

November 1975; 10 pages.

Preferred Metric Dimensions for Round, Square, Rectangular and

Hexagonal Metal Products, CAN3-G312. 2M-1976; Mary 1976; 11 pages.

The above two standards are available from the Canadian Standards

Association, Rexdale, Ontario, Canada.

85

PART 6 - BUILDING SERVICES AND METRIC CONVERSION

6. 1 Overview

Modern buildings are designed to provide a physical and functional

environment in terms of indoor climate, electrical services, lighting,

hydraulic services, and mechanical equipment, which, in combination

account for a substantial part of the total building cost. Rapid

escalation in energy costs—which cannot be attributed to metrication

has forced a wholesale reappraisal of design approaches to use energy

wisely and to extract the maximum utility out of every energy dollar

spent.

It is suggested that metric design for energy conservation and utilization

will be simpler than in U.S. customary units because only a few, coherent

SI units need to be used, thus making alternatives more directly comparable. Since all units for electrical applications are already SI units,

metrication would simply complete the change for other forms of energy.

6.2 Coherent Design for Energy Utilization and Conservation

The use of metric (SI) units would make the understanding of thermodynamics

and mechanical engineering easier. In line with laws of physics, only

one unit, the joule (J), represents all forms of energy, whether mechanical (work), thermal (quantity of heat), electrical, chemical, nuclear, and even molecular, thereby replacing a wide variety of unrelated customary

units

The pivotal role played by the joule is shown in figure 6-1. For example,

a force of one newton (N) applied for a distance of one meter (m) will produce one joule of energy or heat. In the same manner, one watt (W) of

electric power applied for one second (s) will produce one joule of heat

or energy, (1 J = 1 N*m = 1 W*s). More interestingly, the joule remains

the numerator in all compound units, which, in a coherent system with oneto-one relationships, will greatly simplify calculations and reduce

errors

It is easy to appreciate the direct relationship between coherent units,

when it is compared with the traditional situation, where such units as: Btu, therm, horsepower-hour, foot pound-force, and kilowatt-hour are all

used for energy. One SI unit, the watt (W) , which is related on a one- to-one basis to the joule, would replace such variety for power or heat

flow as: Btu/s, Btu/h, Btu/d, fflbf/s, fflbf/min, fflbf/h, horsepower,

and ton of refrigeration, quite apart from the fact that there are different values for the Btu and the horsepower, depending upon definitions,

context, or reference values.

87
Figure 6-1: The "joule" (J) as Pivotal Unit for Energy Design

MAGNETIC ELECTRIC ELECTRIC

FLUX DENSITY INDUCTANCE CURRENT RESISTANCE CONDUCTANCE

ELECTRIC C\ CHARGE,

' QUANTITY

OF ELECTRICITY

ELECTRIC

CAPACITANCE

MOLAR HEAT CAPACITY, MOLAR ENTROPY

Developed by Hans J. Milton, FRAIA

Note: Solid arrow lines indicate that the originating unit is a multiplier

.

Broken arrow lines indicate that the originating unit is in the

denominator

.

Dotted lines indicate that the derived unit is the reciprocal

of the originating unit.

88
If the basic concepts of energy are not clearly defined and understood, it

becomes very difficult to engage in rational design for energy utilization

and conservation. Use of SI units would clarify may hitherto obscure

relationships by means of absolute units and system coherence.

6.3 Electrical and Illumination Engineering

Electrical units used in the United States have been metric units since

they were first defined between 1860 and 1900. The practical units for

resistance (ohm), potential (volt), current (ampere), charge (coulomb),

and capacity (fared) were introduced at the International Electrical

Congress in Paris in 1881, and the unit for inductance (henry) was added at the Congress in Chicago in 1883. It can be said that "coherence" as part of a unit system was first appreciated in electrical and

electromagnetic units. The basis for the use of ampere as the fourth

fundamental property—or as a base unit—was provided in 1901, when the

Italian professor and physicist Giovanni Giorgi proposed a system which

included "The Rational Units of Electrogmagnetism. " [Title of his paper

in 1901.] In 1935, the Giorgi (or MKSA) system was adopted by the International Electrotechnical Association, and it played a prominent part in

the creation, in 1960, of SI, the International System of Units.

The major breakthrough in SI is the unification of mechanical and

electrical units through the watt (W=J/s = V*A) and the joule (J = N*m = W*s), which facilitates most calculations, as indicated in figure 6-1.

Electrical units have been included in the figure to illustrate the

coherence of SI; for example, the ohm (Q, ) could be defined as 1 V/A, or

1 W/A^, or I/S, but the first definition is the one most commonly shown.

Electrical engineering in the United States, therefore, represents a discipline which uses a hybrid system of SI units for all electromagnetic

properties, and U.S. customary units for length and mass, as their derivatives. A change to SI would introduce a minor change in the units

already in use, by replacing the "mho" (reciprocal ohm) with the "Siemens" (S), and the cycle per second (cps) with the "hertz" (Hz = 1/s) —

both on a one-to-one basis, so that numerical values would not be affected.

A change to SI would introduce a major change by giving electrical and

electronics engineers a fully coherent system to work with when customary

units are abandoned. This could increase productivity, especially in

design and production. The Institute of Electrical and Electronics Engineers (IEEE) has had an active interest in metrication, and has used SI

units in most of its publications.

Similarly, illumination engineers in the United States have worked with a hybrid system of SI units for basic illumination properties, and customary

units for length, area, and compound units. SI units, such as the candela

(cd), lumen (lm = cd*sr) and lumen per watt (lm/W) are already in general

use, and the only significant changes needed would be the replacement of

the lumen per square foot (lm/ft^) with the lux (lx = lm/m 2

), and the

candela per square foot, lambert, and footlambert with the candela per

89
square meter (cd/m^). The change to SI units only, again, would simplify

calculations and lighting design. The premier professional society for

illumination engineers in North America, the Illuminating Engineering

Society (IES), has decided to issue the eighth edition of its major

reference document, the IES Lighting Handbook [1], with SI units as primary units and hard conversions. It is expected to be published late

in 1980 or early in 1981.

While the change in units represents few complications, a "hard conversion" of electrical equipment and lighting fixtures and lamps would be more complicated and, in most instances, unwarranted. Should new sizes

or designations be required as part of a "metric range," such ranges

should be developed as new products rather than as conversions, aiming

to reduce variety at the same time. For example, for electric motors,

step increments of 0.5 kW in power output would yield fewer models than

step increments of 0.5 hp (electrical) (0.373 kW). A 2-hp motor (1 .492 kW)

would be interchangeable with a 1.5 kW motor; similarly, a 4-hp motor

[2.984 kW] would be interchangeable with a 3 kW motor, and in the intermediate steps of the range two metric sizes would replace three customary

sizes, for an overall variety reduction of 25 percent. Fluorescent lamps

in customary sizes are already too long for end-to-end installation of

fixtures using the same nominal customary designations. For ceiling

systems using metric modular dimensions such as 1200 mm, a new and shorter

lamp of 1160 mm length would be needed. Major manufacturers have already

conducted extensive research and trial production, but the "metric range"

will take some time to emerge as 80 percent of all production goes into

lamp replacement in existing customary fixtures.

Research into optimum metric sizes, as well as improved design (for

example, the type of end pins used in fluorescent lamps) is regarded as

a desirable part of the metric change which would best be carried out

in the lead-time available before an M-Day and the commencement of

orders for metric products.

6.4 HVAC—Heating, Cooling, Ventilating, and Air Conditioning

The design and integration of heating, cooling, ventilating, and

air-conditioning systems in building is an area where the change to metric

units and metric sizes has been viewed as being of little advantage while

incurring some costs. However, many HVAC design engineers appreciate that

coherent units and decimal relationships will facilitate calculations,

as shown in 6.2.

The major advantage of the change to metric occurs in the use of one unit for pressure and stress, the pascal (Pa), and its decimal multiples,

replacing such a variety of units as:

90
For pressure: psf [lbf/ft 2

] inch H

2 0 (4°C)

foot H

2 0 (4°C)

inch Hg (0°C)

inch Hg (60°F)

psi [lbf/in2

]

47.88 Pa

249.08 Pa

2988.98 Pa

3386.38 Pa

3376.85 Pa

6894.76 Pa

2.989

3.386

3.377

6.895

kPa

kPa

kPa

kPa

atmosphere (std) 101 325.00 Pa 101.325 kPa

For stress: psf [lbf/ft 2

] psi [lbf/in2

] tonf/ft 2 6894.76 Pa = 6.895

95 760.52 Pa = 95.761

[6.894 76 x 106 Pa]

[13.789 51 x 10 6 Pa]

47.88 Pa

kPa

kPa

ksi [kip/in2

] 6.895 MPa

= 13.790 MPa

A major professional society in this field, the American Society of

Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has been

actively engaged in educating its membership on metric issues, and will

have all its publications in dual units by 1981, including the Handbook

series. During the transitional period, the ASHRAE Metric Committee will

continue to disseminate educational material to prepare the membership

for the eventual exclusive use of SI units.

Many of the major HVAC equipment manufacturers have subsidiaries or affiliated companies in metric countries, and have practical experience

with production to metric standards and preferred sizes. It is likely

that metric products would be introduced only when major redesign of

product lines takes place, and that some items, such as pipes, would

remain unaltered. The traditional size designations of pipes were, in

most instances, nominal sizes, and the metric change would offer an opportunity to introduce standard designation procedures, such as specification of internal diameter and thickness, which will automatically

yield the external diameter.

6 . 5 Hydraulic Design and Plumbing

Hydraulic design is concerned with the flow of water and water-based

substances into and out of buildings. It also includes surface water

collection and drainage.

In metric units, hydraulic calculations would be simplified for a number

of reasons:

1. For each physical quantity there is only one unit—especially for

2. Units are coherent, that is, they require no factors in going

from one quantity to another, except decimal factors when going

from a prefixed to a non-prefixed unit, another prefixed unit, or vice versa; and,

pressure;

91
3. There is a direct relationship between the SI unit for volume, the

cubic meter, and the common unit for capacity (liquid volume), the

liter (L), where one cubic meter is equal to 1000 liters. (The

conversion from cubic feet to gallons may be a difficult to remember

conversion factor.)

Water pressure would no longer require a pressure unit of its own, but

be expressed in pascals, or more commonly, kilopascals (kPa). For

example, a head of water of 50 meters (50 m) represents a pressure of:

50 x 9.8* = 490 kPa

[50m3/m2 = 50 000 kg/

2 = 50 000 x 9 . 8* N/m2 = 490 000 N/m2 = 490 kN/m2 = 490 kPa]

*In an absolute system, static load ; must be multiplied by gravitational

acceleration [9.8 m/s 2

] to give absolute force in newtons (N). The

factor 9.8 is an approximation of the internationally standardized

value of 9.806 65 m/s 2

.

Derived calculations are also simplified by coherence between units.

For example, if a pump is required to deliver a flow rate of five liters

per second (5 L/s) at a pressure of 500 kilopascals (500 kPa), what

pump power is required:

3

5 x 10 -3

x 500 x 10 3 = [5 m / s x 500 000 N/m2 = 2500 N-m/s = 2500 J/s = 1000

2500 W = 2.5 kW 2500 W]

The power of the pump motor, in kilowatts (kW) , can be established

directly if the transmission efficiency factor (in percent) is known.

For example, the power with a transmission efficiency of 90 percent

for the above pump would need to be 2500/0.9 W = 2778 W = 2.778 kW. A

three kW motor would be suitable and have some spare power.

These calculations are very much simpler than those in customary units,

because they are coherent units that follow the laws of physics directly.

For a comparison, an example similar to the above would be: using flow

rate In gallons per hour (gph) , water pressure in feet (ft H2O), pressure in pound-force per square inch (psi), power in foot pound-force

per second (ft*lbf/s), and motor power in horsepower (hp).

Another significant advantage of metric units occurs in calculations

involving drainage, run-off, or irrigation. Here, the decimal relationship of the liter (L) to the unit of volume, the cubic meter (m3 ), provides significant shortcuts in calculations. For example, one millimeter

of water distributed over an area of one square meter represents exactly

one liter (1 mm x 1 m

2 = 1 L). This facilitates the calculation of

gutters, channels, and downspouts for run-off. For example, the run-off

from a roof with 200 square meters (200 m

2

) of area and a rainfall of

ten mm in five minutes (120 mm/h) will be: 10 x 200 = 2000 L.

92
Remembering that one liter of water represents a cubic volume equal to

that of a cube with 100 mm sides, the sizing of gutters and downspouts

becomes much simpler than in customary units.

The same principles can be used in reverse; for example, in deciding on water requirements for irrigation or sprinkler systems. How much water

is required to irrigate an area of one hectare (10 000 m^) to the equivalent of five millimeters of precipitation? The answer is easy:

10 000 x 5 = 50 000 L .

As far as pipes and channels are concerned, it is not expected that new metric products will emerge rapidly; rather, as products are developed,

they are likely to be developed in hard metric sizes. There is little reason for most domestic or commercial plumbing fixtures to change,

except for their designation. Current sizes are rarely exactly those

that are used for convenient designation. The exceptions are "builtin" units, such as baths, sinks, or shower bases, which should be

related directly to the dimensions of building spaces into which they are to fit.

6.6 Acoustical Engineering

The science of acoustics uses metric equipment and metric units for

laboratory and site measurement but in acoustic design the square foot

for area and the cubic foot for volume are commonly applied.

The decibel (dB) is a dimensionless unit, or ratio, with a logarithmic

base—and it would not change. The reference quantities for sound power

level (in watts), sound intensity level (in watts per square meter),

and sound pressure level (in pascals), have always been in metric units.

The Acoustical Society of America (ASA) has presented technical information and standards in SI units for a number of years, and most acoustical

engineers do not regard the change to metric measurement as a problem.

REFERENCE

1. IES Lighting Handbook, 6th Edition, Illuminating Engineering Society,

New York, NY; (to be published in Winter of 80-81).

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PART 7 - DEVELOPMENT AND RESEARCH ISSUES IN METRICATION

7 . 1 Investigation and Research

The metric conversion process can be described as an "applied research

and developmental exercise" involving change; namely, the transition to

the use of a different measurement system with different values in most

processes of design, production and construction. In the case of the

U.S. construction community, a better understanding of the issues involved

in the change can be obtained by the examination and study of precedent

in other countries and industries (investigation), and the indepth analysis of particular issues of industry-wide or sector concern (research).

There may also be a need for the trial of alternative approaches

(development) to find optimum technical solutions.

If no investigation, research, or development were to be carried out, timeconsuming and costly errors might be made in the initial phases of a metric

transition, and industry could be locked into suboptimal approaches by

neglect. Further, unilateral actions or decisions in one area could

adversely affect the operations of other segments. As the construction

community represents a multi-disciplinary activity, involving both soft- ware (technical information, standards, drawings, etc.), and hardware

(building products, materials, and built elements), it would be advantageous in most instances to conduct studies by means of multi-disciplinary

groups representing all key viewpoints, except for very specialized and

specific research topics. For example, "task forces" might be established

by industry consent to study metric issues and concerns, and to report

their findings to the industry at large. This would avoid a situation

where decisions would be arrived at without considering both producers

and users, for example, in the determination of optimum product size

ranges

7 . 2 Precedent and International Implications of Metric Conversion

A change to metric units would make the U.S. construction community part

of the metric building world. This would have domestic as well as international implications. A thorough investigation of precedent in metrication in other English-speaking countries may provide shortcuts, give

general guidance on how to deal with specific problem areas, and may point

out which approaches are likely to lead to benefits for the construction

community. It may also point out those which could lead to confusion and,

therefore would best be avoided. An investment in "monitoring and evaluation" of metric developments and precedent, particularly in Canada, could

be recouped many times over in savings of time and costs of conversion.

It has been argued that the United States differs from other countries

that have recently changed to metric units in the construction industry

because of its geographic size, large population, giant industry turnover,

special techniques, and particular form of building control. However,

precedent is worth examining because design procedures, production processes, and construction techniques have become more and more similar the

world over.

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In a developmental sense, a change to metric units would make it more

important to interact at the international level, particularly in standards development activities. This has been recognized in Section 6.

(6) of the Metric Conversion Act of 1975, which deals with international

consultation and cooperation.

The assessment of international standards in national standards-related

activities is heavily promoted in Title IV of the Trade Agreements Act

of 1979 [1], as is the intent to make U.S. viewpoints known at the

international level. Section 402.(2) of the Act deals with the "Use of

International Standards" and prescribes that "each Federal agency, in

developing standards, shall take into consideration international stanards and shall, if appropriate, base the standards on international

standards." More significantly, the Act states in Section 403, on "State and Private Standards-Related Activities," that "It is the sense

of the Congress that no State agency and no private person [defined to

include any corporation, partnership, association, or other legal entity]

should engage in any standards-related activity that creates unnecessary

obstacles to the foreign commerce of the United States," and that "The

President shall take such reasonable action as may be available to promote the observance by State agencies and private persons, in carrying

out standards-related activities, of requirements equivalent to those

imposed on Federal agencies under Section 402, and of procedures that

provide for notification, participation, and publication with respect to

such activities."

In the longer run, therefore, ignoring the existence of international

proposals and standards could have serious consequences for U.S. industry and industry organizations whether in the provision of technical

data or services outside or within the United States, or in the sale of

products. As metric conversion offers a unique chance to harmonize

domestic and international approaches, it is recommended that the implications of worldwide trends be studied fully, so that where appropriate,

they can be taken advantage of should the construction community decide

on conversion.

7 .3 Basic Metric Issues

The fundamental issues in a change to another measurement system revolve

around the selection of suitable units and numerical values which will

maximize the opportunities that come with change and minimize any

dislocation, confusion, and cost.

While ample information on good metric practice is already available, a number of aspects of unit use in building design have not been resolved.

These require detailed study. Some examples of the topics which should

be assessed are:

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1. What metric units are to be used in the field of moisture (vapor)

movement through building materials and condensation in building?

2. In thermal design, what could take the place of the degree day and

traditional R-values?

3. Is there any need to replace the unit sabin in acoustical calculations,

and, if so, with what form of unit?

4. What would be appropriate units to describe flow rates for a variety

of applications, as well as in compound units, such as air

infiltration, water consumption, etc.?

The major concern in metric conversion occurs in relation to the selection

of "preferred" and "convenient" numerical values. Such values are important in a "hard conversion," that is, where a definite change is proposed.

By comparison, a "soft conversion" simply requires reasonably rounded

metric equivalents and, where possible, convenient values. Research

studies would be desirable to identify:

a. A methodology for the presentation of dual unit statements In which

a "hard conversion" can be distinguished from a "soft conversion"

and which can be applied on an industry-wide basis.

b. General guidelines for conversion, rounding, and rationalization,

with practical examples of "preferred values," number series, and

variety reduction.

c. A classification system for building products according to the degree

of conversion that would be required or desired, ranging from no change to extensive change.

7 . 4 User Studies to Determine Suitable Metric Design Dimensions

A change to preferred metric values in building would alter many of the

traditionally accepted dimensions in building design and production; for

example, a room height (floor- to-ceiling height) of 8 feet (2438 mm)

could be replaced by a metric dimension of 2400 mm, which is 38 mm or 1-1/2" less; or, 2500 mm, which is 62 mm or 2-7/16" more. Examples of

functional dimensions in building are numerous, such as clear heights,

vertical clearances, horizontal clearances, minimum room widths, clear

opening widths, height of work planes, height of guard rails, geometry

of stairs and steps, design dimensions for the handicapped, etc. Studies

which have led to "convenient" or "preferred" customary values should be

reappraised to ascertain their validity in a metric context, and to determine whether metric preferred values would give equivalent safety, con- venience, and economy, or whether user needs have changed. It is likely

that such research would show that many customary values have been

arrived at on the basis of numerical convenience rather than functional

requirements, or by a mixture of the two.

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A number of specific research studies are suggested for consideration:

1. Research into anthropometric factors of the American population, to

give metric design guidance based on up-to-date statistical information on human dimensions of various profiles of the population such

as children, adults, and the elderly, with differentiation of male

and female dimensions and five percent, 50 percent, and 90 percent

ranges. Most data now available were obtained many years ago, and

it is possible that changes have occurred.

2. Research into human space needs (based on up-to-date anthropometric

data) and the design of functional spaces, especially in dwellings,

to determine whether minimum standards are appropriate and what

"metric minimum standards" might be.

3. Research into the functional validity of width of egress dimensions

(hallways, corridors, stairs, and exitways), based on 22" [559 mm]

multiples, which have been used in many building code requirements.

This research would show whether arithmetic or geometric progressions should be used in the selection of egress dimensions, and

give guidance in the selection of the most suitable metric

replacement values.

In addition, user studies might be expanded to take into account room

areas and/or volumes.

7 . 5 Dimensional Coordination Research

Considerable research has been carried out in the United States and

worldwide into the principles and practical application of a system of

dimensional coordination in building. Broad agreements have been reached

at the international level on a basic module of 100 mm and certain preferred multiples for building and building product dimensions. However,

international preferences do not include the metric equivalent of the

traditional U.S. dimension of 16 inches (406 mm) or 4 modules—400 mm—as

a direct multimodular preference. It is probable that U.S. recommendations for metric dimensional coordination would be somewhat different

from international recommendations.

A number of research projects are needed to deal with specific aspects

of (metric) dimensional coordination, such as:

1. What will be the impact of the 100 mm module, as a substitute for

the 4-inch module, on building design and design standards; building

codes and minimum requirements; building products and manufacturing

processes; and, on-site layout and assembly processes?

2. What would be the optimum dimensions for functional spaces and spans

in buildings, based on the 100 mm module? Where could traditional

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recommendations be reduced and where could they be enlarged advantageously? Where can changes arising from energy considerations be

coupled with changes resulting from or required by metrication?

3. How could product ranges be rationalized, using preferred (modular)

sizes as basic sizes, and non-preferred sizes as special sizes?

4. What would be the economics of dimensionally coordinated (modular)

design versus non-coordinated design? Would metric units and pref- erences facilitate computer design and documentation (or, does the

computer facilitate coordinated design)?

5. What would be the economics of producing dimensionally rationalized

products? Could the overall product range be reduced without a loss

of sales? What would be the advantages and disadvantages in distribution and transportation? Is there scope for improved modular

packaging?

6. What would be the costs and benefits of metric construction layout and

assembly, using dimensional coordination principles and coordinated

products? Would improved construction accuracy result?

7. What reeducation and training would be required to increase the use

of dimensional coordination in the construction industries?

While the investigation of these aspects of (metric) dimensional

coordination would have to rely on the judgment and opinions of people

involved in design, production, and construction, it is important that

any research studies undertaken involve the actual designers and builders

to yield the most useful results. It may be worthwhile to use correlating

groups of people who have been involved in the application of (metric)

dimensional coordination and those who have not, to ascertain differences

in opinions.

7.6 Investigation of Design and Documentation Aspects

The change to SI units would require the revision of almost all technical

data and standards used in building design. In a transition, three

approaches could be used to deal with technical information:

1. the conversion of existing data and design aids;

2. the conversion and rationalization of existing data and design aids;

and

,

3. the development of entirely new technical data and design aids.

Investigative effort and research studies should be aimed at the

identification of technical data needs in the design process so that

priorities for conversion could be allocated. Unless design data and

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aids are available in time for metric project design, considerable

professional and technical efforts might have to be spent in developing

data on a project-by-project basis, which could adversely affect the

economics of metric design. Many of the design aids now in use have

been developed with particular reference to U.S. customary (inch-pound)

units to facilitate decision-making; for example, tables, charts, monograms, etc. Some of these would no longer be required because of the

coherence of units in SI; however, others would need to be revised or amended. There is ample scope for the simplification of design data

and design aids in metric units, especially in energy design information

where fewer and coherent units would be used.

7 . 7 Investigation of Building Codes and Standards

A special aspect of the review of technical data during a conversion

would be the need to develop metric versions of building codes, related

design codes, and building standards. It is widely agreed, and generally supported by the findings of the U.S. Metric Study and the GAO

Metric Study, that simplification and harmonization of American building codes would be a major opportunity in a change to SI, which could

yield long-term benefits to the construction community. Therefore, a major research effort should be aimed at "opportunities for improving

building codes and standards during metrication. " In the GAO Metric

Study, associations representing codes and standards organizations, labor,

distributors, contractors, and designers all agreed that conversion would

provide such an opportunity.

Rather than aiming metric investigations and research efforts over the

broad spectrum of building codes and standards, selected areas of con- cern or opportunity might be isolated and studied in-depth to develop

optimum metric recommendations.

Among the topics that merit detailed analysis would be:

1. Units and preferred values for loads and forces acting on buildings,

such as live loads, dead loads, wind loads, snow loads, seismic

forces, etc., based upon up-to-date data.

2. The research-based development of (metric) performance requirements

for building elements and the building environment, with particular

reference to international standards or proposals in this area.

3. The research-based development of (metric) compliance tests for

building elements, products, and systems, taking note of

international recommendations and standards.

7 . 8 Investigations Into Building Products and Production Processes

Metrication implies "review," though not necessarily wholesale change

of customary products (sizes), processes, and procedures, with a view

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to obtaining more cost-effective and functionally efficient metric

alternatives

Many products need not be changed, as they require modification within

present production tolerances only because existing standard (or specified) sizes convert to convenient metric dimensions. Only where dimensional coordination impacts would it be reasonable to make changes. The

research and developmental decisions facing producers and producing

sectors revolve around rationalization of construction product lines,

that is, the possible replacement of existing ranges with smaller or functionally superior metric ranges. Research into optimization proposals requires an assessment of all processes from the raw materials

stage to the consumer. The development of a production/distribution/

use model for products or product groups may yield many useful data for

rationalization.

It has been pointed out that the rationalization of product lines is an opportunity that exists at any point in time. However, without a farreaching industry-wide change—such as a change to metric measurement

there is no strong catalyst for change. It is also possible that proposals would be hampered by actions in the marketplace, with opposition

from interest groups and competing manufacturing interests. The lumber

industry provides an insight into the difficulty of "change" without an external cause such as metrication. In 1970, the industry went through

a major and controversial change in softwood lumber sizes, grading standards, and engineering design values, which represented something akin

to a "hard conversion." The project required many years of inter-industry

meetings, hearings, technical and engineering discussions, and research

and developmental activities. The lessons were that research, early

planning, and good communication are essential to a smooth change. Based

on this preparation, the actual changeover went smoothly, quickly, and

easily for manufacturers, distributors, and users, despite some minor

concerns in the marketplace.

Industry associations are in a key position to play a prominent role in

"research and developmental" activities such as:

1. the determination of optimum sizes for products based on manufacturing

and user requirements;

2. the assessment of the impact on standards and standard details,

energy use, and end-use productivity;

3. the development and distribution of technical information to

facilitate conversion and familiarization; and,

4. the consideration of industry-wide aspects of timing for the change.

The experience of similar industry groups in metrication, notably that

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of Canadian industry, may provide significant guidance in these activities. (For example, the Canadian steel industry is now producing some

of the products and sizes likely to emerge in the United States if metric

demand increases.) These research activities would be desirable, regardless of specific target dates for conversion, as the lead-time required

to harness "opportunities" is seldom long enough.

It is recommended that investigations be centered on "productivity,"

including warehousing and distribution as well as manufacture. Often

the costs of inventory-holding are a major factor in construction product

cost, and sometimes they determine the difference between profit or loss

from operations. Productive metrication not only means streamlining

product lines and processes, but minimizing "dual" production runs and

"dual" inventories. Again, the study of precedent may yield useful

guidance on how to minimize the costs and disruption, if any, resulting

from duality. Precedents in "catalog optimization research" are found

in "metric fasteners" and "metric reinforcing steel," and the approaches

taken in these segments of the metals industry may provide useful models

for other industry segments.

7.9 Investigation of Metrication in Construction and Maintenance

The role of the contracting industry in metrication has been described as

a passive one in the early stages of conversion, until such time as designers begin to prepare metric documentation and producers gear up

for metric production. This assessment ignores the significance of

measurement-based operations on construction productivity. The use of

decimal measurement to replace the variety of units now in use would

facilitate estimating, layout, purchasing decisions, and general on-site

construction activity.

Ideally, investigations should have commenced to identify all areas where

improvements in on-site operations might be affected in tandem with a conversion; for example, in layout, use of materials, positioning and

assembly of components, and maintenance of construction accuracy.

Specific areas for investigation and research might be:

1. What are the most common causes of on-site error or inaccuracy in

current construction, and are there opportunities to avoid such occurrences in metric construction by altering techniques of measurement

or assembly?

2. How can metric dimensional coordination be facilitated in construction? What techniques might be used, altered, or developed? What

equipment is essential, and what is helpful?

3. What training or familiarization of site personnel is required? What

types of training aids and documents are needed?

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The role of construction unions in metric research has primarily been

related to the concern that construction personnel might not be able to

cope with metric work unless given extensive training, as well as assistance with the replacement of tools. The investigation of experiences

in other sectors of the economy (such as the automotive industry), and

other countries (particularly, Canada) would be useful to determine the

extent of these problems. Some reports dealing with actual metric work

experience in other countries stress that construction personnel, once involved in metric operations, prefer to remain with metric units and

not switch back to customary units thereafter.

Some concern has been expressed by designers and building owners about

the potential difficulties associated with the repair and maintenance

of "non-metric" buildings and plant. No direct research evidence is

available of either iiTcreased costs or specific difficulties encountered

in other countries in the field of building maintenance and rehabilitation. The repair and rehabilitation industry has developed an ingenious

capacity to deal with situations involving non-availability of materials

and parts, and many lessons can be learned from current practices in

non-metric units. The entire subject area represents a major "applied"

research project.

7.10 Adaptation of Materials During A Transitional Period

A similar aspect of a change to metric measurement would be the adaptation

of building products and materials during the transitional period. First,

that of customary sizes to fit with metric building designs and, second,

that of metric sizes to fit with non-metric building designs. Both would

occur. The advantage of new construction work is that decisions can be

made, or amended, before the building is irretrievably constructed. For

example, if the size of reinforcing steel should change to new metric

sizes during the construction life of a project, a design check and,

possibly, some minor changes in spacing may be needed. If, however, a building designed in customary units is to be built at the end of the

transitional period, some customary products may no longer be available,

and metric products would need to be adapted. Other industries have

coped successfully with such a transition, so that there is no reason to

suspect that the U.S. construction community would be unable to do so.

It would be desirable to undertake investigations early so as to identify

and analyze areas where "adaptation problems" might arise.

7.11 Research Into Legal Implications, Contracts, and Agreements

While the metric system, by public law, has been permitted to be used in

the United States for over a century, there are many existing statutes,

regulations, and ordinances which state requirements expressed exclusively

in U.S. customary units. Such laws or regulations could provide barriers

to the selection and use of alternative, "hard converted" (preferred)

metric values, especially, if they establish minimum or maximum acceptance

levels that would preclude the choice of a preferred metric alternative.

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For example, a minimum requirement of 4 feet (1219 mm) would preclude

the use of a modular preference of 1200 mm, or a maximum pressure of

250 lbf/ft 2 (11.97 kPa) would preclude the use of a preferred 12 kPa as design criterion.

The identification of critical laws or regulations which have a measurement impact on design, production, and construction represents a major

task. Within this task, there is the research activity of determining

any critical values or requirements that might inhibit the use of "hard

metric" alternatives, necessitating a study of the basis of traditional

measurement values and their amenity to change.

Another research area involves the implications of product unavailability

and substitution, including methods of compensation for extra costs, if

any, of obtaining specified products. Substitutions, as well as extras,

have always been a feature of construction contracts, and safeguards

would need to be established to ensure that neither the contractor,

nor the building client becomes the victim of "metric" costs that were avoidable either by design decisions or by purchasing decisions. A

special metric contract clause may be desired during a transitional

period

.

Labor agreements and awards contain some measurement-related clauses,

and these would need to be identified. In some instances, they may

need to be amended to coincide with a new measurement environment. In

general, a change should neither reduce awards nor increase labor costs,

so that a conversion would need to be effected within a fair and equivalent range. However, a give-and-take approach may prove to be more economical in the longer run, and alternatives should be researched by

employer as well as employee groups, preferably by a joint task force.

7.12 Research and Development in Perspective

It has been suggested by metric experts in other countries that have

completed the change to SI that metrication represents one of the

greatest "review" opportunities of modern times—no established value,

benchmark, or practice is sacrosanct! However, judicious management is

required to prevent metrication from becoming the greatest "research

exercise" of modern times, with industries and organizations waiting

for the results of research before embarking on any change.

A change to SI represents an opportunity to analyze traditional approaches

and their validity in a modern technological environment. The opportunity

to change to preferred values and rationalized ranges must be duly considered, if greater economy and productivity is to result from such

change. It is in this area that thorough research rather than superficial

assessments will be needed.

The entire construction community can perform a major role by developing

a coordinated list of worthwhile metric research projects, so that the

104
research resources available to the industry can be harnessed and used

wisely.

REFERENCE

1. Trade Agreements Act of 1979, Statements of Administrative Action,

House Document No. 96-153, Part ii, 96th Congress; U.S. Government

Printing Office, Washington, D.C.; 1979; Title IV-pp. 211-233.

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PART 8 - TIMING OF METRIC CONVERSION IN THE CONSTRUCTION INDUSTRIES—AN

ASSESSMENT OF CRITICAL ACTIVITY ITEMS

8. 1 Key Features of a Timetable for Conversion

A timetable for conversion should show "what needs to be done" (the key

action items in conversion), "when it should be done (a time frame for

accomplishment), and " who is principally responsible for it" (the lead

group for the accomplishment of an activity, and others affected).

In the United States there is no formal national commitment to metric

conversion or a national time frame for the change. It is left to individual sectors and industries to determine whether or not to convert,

when to convert, and in what mode to convert (soft vs. hard conversion).

The Construction Industries Coordinating Committee (CICC) of the American

National Metric Council (ANMC) has examined metric issues and developed

a plan for voluntary conversion. The plan includes a "Construction

Industries Metric Conversion Timetable.

This timetable, shown in Part 1 (figure 1-1), goes beyond the timetables

developed in other countries, by indicating which sectors would have a "lead role," as well as which other sectors would be involved in each

action item. This allows industry sectors, associations, and individual

organizations to plan specific and general responses, and to concentrate

on those areas where they would be primarily involved.

The ANMC/CICC Construction Industries Metric Conversion Timetable represents an attempt by private sector groups to develop a schedule for a voluntary conversion in the construction industries. The timetable is

the outcome of lengthy investigation and planning activities, and has

been submitted for public scrutiny and comment. Like any timetable, it

is a "best guess" of the time scale necessary for conversion by people

familiar with industry activities who have also studied relevant metric

issues. As it provides time periods for each activity item, it would

allow both early and late starts in actual implementation, but within a framework of relationships to other program items.

The timetable shows a series of calendar years during which conversion

activity would take place. It also uses the concept of an "M-Day" as a focal reference point in time to signify the key event(s) in the industry;

namely, the change from customary units to metric units in the production

of materials and the construction of buildings. The M-Day is the threshold in the program where hardware in metric sizes will become available,

and it can be likened to "noon" as a point in time which divides "ante"

(a.m.) from "post" (p.m.). An industry-agreed M-Day would simplify metric

management decisions—at any particular date there is a clear indication

of lead-time left to the point of transition.

107
In practice, conversion activities in a sector would take place over periods

of time, rather than instantaneously. Individual organizations would probably phase in their changeover when the time for conversion is at an optimum.

Some organizations may attempt to start early, others may wait until the

bulk of the industry has converted. This means that each action item will

have a "transition period" of some length, any amount up to a number of

years. The timetable uses a graphical method to illustrate "phases" in

the change.

Figure 8-1: Graphical Illustration of "Phases" in a Change

Schedule Code: Preliminary Metric Conversion Activity

More and more organizations become involved

Intensive Metric Conversion Activity

Most of the required changes are made

Decreasing Metric Conversion Activity

Any remaining changes are made

Normal Metric Activity

Metric measurement has become predominant

An understanding of the timetable and its intention is of great importance.

As part of the planning process, ANMC/CICC prepared supplementary metric

conversion schedules, or timetables, for individual sectors. The supplementary schedules amplify certain items but are otherwise in full agreement. Full details are contained in ANMC publication "Metric Conversion

in the Construction Industries—Planning, Coordination, and Timing" [1].

8 . 2 Action Items in the ANMC Construction Industries Metric Conversion

Timetable

The ANMC/CICC Construction Industries Metric Conversion Timetable, shown

in figure 1-1, lists 23 action items. An understanding of the meaning and

general intent of these action items is desirable to ensure the best

phasing corporate research, developmental, production, and educational

activities in compliance with industry-agreed time phases. No specific

description of the scope of individual action items in the timetable has

108
been provided by ANMC/CICC, altbougb more detailed subdivisions of action

items are given in activity descriptions prepared by tbe individual CICC

Sectors. These activity descriptions have been relied upon in the discus

sion of the technical content or scope of each action item.

8.2.1 Publish Metric Practice Guide for Construction (and Revise)

Preliminary Phase: 1978/79

Intensive Phase: 1980/81

Residual Phase: 1982

A metric practice guide is the major technical "desk reference document" for

the transitional period. It is intended to provide technically correct

information on conversion approaches and procedures, including the selection

of preferred values (rationalization) and rules for writing and documentation (drawing practice) in metric (SI) units. Supplementary metric practice

guides for specific sectors and subsectors would be based on the general

metric practice guide for construction.

While no comprehensive metric practice guide for the building community has

been prepared, parts of metric practice guides have emerged through national

standards-generating organizations with broad general agreement on rules

and recommendations. Some such organizations are the American Society for

Testing and Materials (ASTM), American Society of Mechanical Engineers

(ASME), American Society of Heating, Refrigerating and Air-conditioning

Engineers (ASHRAE), Institute of Electrical and Electronic Engineers (IEEE),

and Illuminating Engineering Society (IES). The most comprehensive document

on the use of SI units currently available to the industry is the ANSI/ASTM

Standard E621-78, "Standard Practice for the Use of Metric (SI) Units in

Building Design and Construction" [2].

Another reference document which provides a comprehensive set of metric

practice guidelines is the "AIA Metric Building and Construction Guide"

[3].

8.2.2 Develop Necessary Basic Metric Standards

Preliminary Phase: 1978/Mid-1979

Intensive Phase: Mid-1979/1981

Residual Phase: 1 982/Mid-l 983

The task of establishment of standards objectives, identification of new

standards needed and existing standards requiring conversion, as well as the overview of the development of basic metric standards required in the

construction community (including priorities for development or conversion), is a key function of the Construction Codes and Standards Sector,

the most active Sector in ANMC/CICC. The Sector and its Subsectors are involved in the standards identification phase, although a varying degree

of conversion and rationalization activity is taking place in most national

standards-generating organizations

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Key standards include documents dealing with design loads; structural

design in concrete, steel, masonry, and timber; dimensional coordination

of buildings, building materials, and systems; building services design

concepts (HVAC, electrical, illumination, plumbing, etc.); performance

aspects of major building materials or components; design for special

occupancies (handicapped, elderly, children, etc.); and, space standards

for building occupants, equipment, and vehicles.

8.2.3 Determine Product Sizes in Metric Units

Preliminary Phase: 1978/Mid-1980

Intensive Phase: Mid-1980/1984

Residual Phase: 1985—ongoing as normal metric activity

The determination of metric product sizes is a prerequisite to the

production of genuine metric materials, components, and systems. The

process of deciding on suitable and preferred sizes involves interindustry meetings and discussions, the preparation of draft proposals and

draft standards, and the finalization of metric product standards.

Considerable effort already has been undertaken in determining product

sizes for steel products, reinforcing materials, masonry units, building

lumber, and glass. More detail on this is given in Part 5. The existence

of dimensional preferences, outlined in Part 6, will assist industry

sectors to arrive at preferred metric product sizes and ranges.

8.2.4 Produce Metric Measuring Equipment

Preliminary Phase: Mid-1979/1980

Intensive Phase: 1981/1984 (inclusive)

Residual Phase: 1985 —ongoing as normal metric activity

This action item is shown in seventh place in the ANMC/CICC Timetable,

but chronologically and logically might be shown earlier to maintain the

internal sequence and relationships of the timetable. For this reason

it is discussed at this point.

Metric measuring equipment will be needed for design and documentation,

production (including research, development, and testing), and on-site

construction. The equipment involved ranges from simple scales for mass

(weight), gauges for measurement of pressure or stress, and thermometric

devices. A wide range of equipment in metric (SI) units is already

available and used in laboratory and other work, in other, partially

metric industries, and in the Canadian marketplace. As with construction

products, it is desirable to develop national standards for metric measuring equipment which include the use of correct units, suitable graduation

or scales or dials, and tests for accuracy of the measuring device.

8.2.5 Decision to Build Metric Building

Preliminary Phase: 1 980/Mid-l 981

Intensive Phase: Mid-1981/1984

Residual Phase: 1985—ongoing as a normal metric action

110
The accomplishment of conversion is dependent upon decisions by clients to

build metric buildings in accordance with an industry-agreed timetable.

Clients need to be assured that a metric building will not incur additional construction costs or time. The building decision, to a large

extent, guarantees metric demand, although a point in time will be reached

in the transitional period where non-metric construction could create a degree of premature obsolescence in a building and, thus, might not be in

the best interest of the building client. It would be expected that most new construction after the M-Day would be carried out in metric measurement, as would all new design.

8.2.6 Award Design Contract [for Metric Design]

Preliminary Phase: 1981/Mid-1982

Intensive Phase: Mid-1982/1985

Residual Phase: 1986—ongoing as normal metric activity

This timetable action item is a logical extension of a decision to build

a metric building, and has a one-year displacement in the schedule. Of

course, design contracts for metric buildings outside the United States

have been awarded to U.S. design organizations for some time. However,

this item would relate specifically to design work within the United

States.

8.2.7 Begin Conceptual Design in Metric

Preliminary Phase: 1981

Intensive Phase: 1982/1985

Residual Phase: 1986—ongoing as normal metric activity

This action item is shown in eighth place in the ANMC/CICC Timetable,

but chronologically and logically follows the award of the design contract for a metric building, particularly, as the timescale provides for

substantially the same durations. Conceptual design in metric units is

dependent upon the availability of key reference documents setting out

space requirements and acceptable (minimum) standards for activity areas and accessibility in metric dimensions. Conceptual design will also be

aided by agreed dimensional coordination guidelines.

8.2.8 Develop and Distribute Metric Product Literature

Preliminary Phase: Mid-1980/Mid-1981

Intensive Phase: Mid-1981/1985

Residual Phase: 1986—ongoing as normal metric activity

While shown in sixth place in the ANMC/CICC Timetable, this action item is

highly dependent upon the determination of product sizes in metric units

(8.2.3) and decisions by industry segments or individual companies to

market or foreshadow metric products. (A number of metric roofing products are already available, as indicated in 5.9.) Some metric product

information may also have been developed for external markets, such as Canada.

Ill
In some instances, one product line with two sets of product literature

may be all that is needed to accomplish conversion, and the steel industry

provides some useful precedent with the description of steel sections and

shapes in both U.S. customary units and metric units. In other product

groups, product literature needs to be distinguished clearly and carefully

to differentiate between non-metric and metric products. During a transitional period, product literature will be a major source of technical

information, and it is important that it be developed in correct SI units

and with correct presentation of symbols and numbers. Metric catalogs

and listings of metric product literature probably should be stored

separately from other data for easy access and retrieval.

8.2.9 Publish Model Codes in Metric

Preliminary Phase: Mid-1980/1981

Intensive Phase: 1982/1984

Residual Phase: 1985 —ongoing as normal metric activity

Metric units in model codes can take the form of dual values, either as direct equivalents or as alternative values, or a metric supplement (as

used initially in the National Building Code of Canada), or as a separate

metric edition. Each approach has some advantages and some drawbacks.

In general, the further the change has advanced, the more need there is

to incorporate preferred metric values.

One of the strategies for a smooth transition is to work towards a "hard"

metric version in successive editions. This can be accomplished by selecting convenient alternative metric values in all cases where full interchangeability is not required and where no industry standards have been

drafted or issued. However, it should be done with the proviso that any

metric values shown can only be used with metric documentation and cannot

be reconverted to U.S. customary units to obtain a more advantageous

compliance value. In this manner both customary and metric preferred

dimensions can be accommodated in one document. This approach would

eliminate many "nuisance values" from model codes and subsequent statutory

documents based upon them.

8.2.10 Enact Enabling Legislation [for Metric Requirements]

Preliminary Phase: Mid-1980/1981

Intensive Phase: 1982/Mid-1983

Residual Phase: Mid-1983/1984

This action item is shown in eleventh place in the ANMC/CICC Timetable,

but chronologically and logically might be shown directly after the

publication of model codes, as it is designed to provide the legal basis

for the enactment of metric (building) requirements. The enabling legislation need not indicate specific values in either measurement system, but

rather prescribe the maximum extent of permissible modification to requirements to facilitate their acceptance at state or local government levels.

The enactment might also stipulate certain dates for acceptance of documents

submitted entirely in metric units and, possibly, a target date after which

metric documents will be preferred.

112
8.2.11 Conduct Land Transactions in Metric

Preliminary Phase: Mid-1980/1981

Intensive Phase: 1982/1983 (inclusive)

Residual Phase: 1984 —ongoing as normal metric activity

This action item is shown in twelfth place in the ANMC/CICC Timetable,

but might be shown directly after the enactment of enabling legislation,

as such legislation may be required before land transactions and registration can take place in metric units. Precedent has indicated that

the least expensive transition is accomplished if land transactions are recorded and titles issued in metric units only on an ongoing basis so that the additional cost, if any, is marginal. Again, for effective

operations, target dates should be set at the local level to minimize

transitional difficulties.

8.2.12 Produce Property Surveys in Metric Units

Preliminary Phase: Mid-1980/1981

Intensive Phase: 1982/Mid-1984

Residual Phase: Mid-1984/1985—ongoing as normal metric

activity

This timetable item is closely related to the conduct of land transactions

in metric units. Metric surveying equipment is already available, and the

surveying and mapping community has developed a practice guide for metric

activities [4], At the national level, topographical quadrangle maps with

ratio scales and metric contour elevations have been published by the

U.S. Geological Survey in cooperation with several states, and state plan

coordinate systems are being adapted to SI with the assistance of the

National Geodetic Survey of the National Oceanic and Atmospheric Administration (NOAA).

8.2.13 Develop Metric Estimating System

Preliminary Phase: Mid-1980/1981

Intensive Phase: 1982/1984 (inclusive)

Residual Phase: 1985

The development of a metric estimating system in building is shown as the

tenth item in the ANMC/CICC Timetable, but might be shown in a later action

item, since it represents the first activity in which the contracting

community will become involved significantly as a lead sector. The

coherent relationships between SI units and metric dimensional coordination should facilitate the development and maintenance of a metric estimating data bank, and thus assist contractors, designers, producers, and

users. The preliminary phase might be used to develop suitable computer

programs

8.2.14 Begin Design Development and Engineering in Metric

Preliminary Phase: 1982/Mid-1983

Intensive Phase: Mid-1983/1985

Residual Phase: 1986—ongoing as normal metric activity

113
The development of detailed architectural designs and engineering calculations in metric units represents the first major commitment to a metric

mode of building. Design development and engineering are somewhat dependent upon the availability of standards and product information, as well

as general agreements on metric product availability. The objective of

metric design should be to minimize the amount of new non-metric construction after the construction industry M-Day—that is, if the design is

expected to go into the field in 1985, or thereafter, it would be advisable

to use metric (SI) units.

8.2.15 Estimate and Bid on Metric Documents

Preliminary Phase: 1983

Intensive Phase: 1984/1985

Residual Phase: 1986 —ongoing as normal metric activity

If the ANMC/CICC Timetable is adopted by the construction community,

construction contractors are likely to be faced with metric documents from

1983 onwards. This represents the first test for the metric estimating

system developed by contractors and subcontractors. Whereas bidding on early projects may be more difficult than competing for nonmetric work,

it will build up metric judgment and expertise and is likely to pay

dividends later when major clients will look for organizations with proven

metric capability.

8.2.16 Award Metric Construction Contract

Preliminary Phase: 1983

Intensive Phase: 1984/1985

Residual Phase: 1986—ongoing as normal metric activity

The award of a metric construction contract represents the second major

commitment to a metric mode of building. It will give a building client

a structure with minimum built-in obsolescence, compared with a non-metric

building carried out at the same time. The construction contract needs

to include safeguards for all parties in the event of unforeseen difficulties. It would be unreasonable to hold the contractor responsible for

all non-availabilities; similarly; it would be unreasonable to have the

client pay for substitutions or extra work that could clearly have been

avoided. Precedent has indicated that early metric jobs are generally

better planned and managed to avoid pitfalls; therefore, "extras" are less rather than more likely to occur.

8.2.17 Accept Plans in Metric and Issue Building Permits

Preliminary Phase: Mid-1983/1984

Intensive Phase: 1984/1985

Residual Phase: 1986 —ongoing as normal metric activity

Metric construction activity cannot eventuate without approval of metric

plans and the issuance of a building permit. Ideally, plan approval

should be based on statewide or regional agreements and target dates to

minimize disruption.

114
8.2.18 Obtain Labor Agreements in Metric

Preliminary Phase: Mid-1983/End-1983

Intensive Phase: 1984/Mid-1985

Residual Phase: Mid-1985/End-1985

The identification of measurement sensitive labor agreements and their

review and restatement in sensible metric terms is one of the shorter

activity items in the ANMC/CICC Timetable. It should be fully accomplished

within a period of one year from the proposed M-Day.

8.2.19 Begin Construction of Metric Buildings

Preliminary Phase: 1984

Intensive Phase: 1985/Mid-1986

Residual Phase: Mid-1986/1987 —ongoing as normal metric activity

This action item has been shown in a heavier outline as it represents the

focal item in the Timetable—namely, the transition to the use and assembly

of metric hardware. It is closely allied to the production and delivery

of fully metric building materials and components.

It is anticipated that some trial or pilot projects will be commenced

prior to the designated industry M-Day, and that metric construction will

accelerate rapidly thereafter. Within two years from M-Day, all new projects should be constructed in metric units as a normal mode of operation

to minimize the duration of the transitional period, and dual production

lines, dual inventories, etc. Metric training of construction personnel

can be undertaken either on the job, or immediately preceding the involvement in metric tasks.

8.2.20 Deliver Metric Products to Suppliers and Site

Preliminary Phase: Mid-1984/End-1984

Intensive Phase: 1985/1986

Residual Phase: 1987 —ongoing as normal metric activity

This action item is sequential to the production of metric materials and

components, and shows general overlap with metric construction activity.

The availability of metric products will determine the ease with which

metric construction can proceed. A suitable identification system is re- quired to differentiate metric and non-metric products in the transitional

period

.

8.2.21 Complete Metric Construction

Preliminary Phase: 1985

Intensive Phase: 1986/Mid-1987

Residual Phase: Mid-1987/1988—ongoing as normal metric

activity

At first sight, this action item seems superfluous, especially as with

its accomplishment the point will be reached where all new construction

is carried out in metric units. However, the timescale shown indicates a

115
lag time of one year between activity items 19 and 21 (begin metric con- struction and complete metric construction), which may be taken as an approximation of "average" construction duration. Individual targets for

commencement and completion of metric construction have to be set for

each project, and the inclusion of this action item serves as a reminder

that the completion date is just as important as the commencement date.

8.2.22 Occupy and Maintain Metric Buildings

Preliminary Phase: 1986/Mid-1987

Intensive Phase: Mid-1987/1988

Residual Phase: 1989 —ongoing as normal metric activity

The occupancy and maintenance of "metric" buildings signifies the accom- plishment of the changeover. Apart from any clearance or loading signs

there will be few direct reminders that a building is a metric building.

Maintenance should be easier as general repair or maintenance items in

metric sizes increasingly will become available.

8.2.23 Conduct Real Estate Transactions in Metric

Preliminary Phase: Mid-1986/Mid-1987

Intensive Phase: Mid-1987/1988

Residual Phase: 1989—ongoing as normal metric activity

The ANMC/CICC Timetable envisages that real estate activities in metric

units will follow rather than run in parallel to metric conversion in the

construction industries. To a large extent, the change in real estate is

a change in the descriptions only (that is, the software), which can be

accommodated by means of a soft conversion and/or dual units during a transitional period until such time as estate agents, sellers, and purchasers

become familiar with metric units.

8 . 3 Some Comments on the ANMC/CICC Construction Industries Metric

Conversion Timetable

The ANMC/CICC Construction Industries Metric Conversion Timetable is

complemented by a number of Sector timetables which show greater detail

in the action items. They include periods for familiarization or training

of construction industry professionals, technicians, site personnel and

labor, and office staff; research and developmental activities; and,

generally, an expansion of items relevant to the particular Sector.

It is significant that in the review of the ANMC/CICC Timetable by

committees, individuals, and representatives of industry groups, there seems to have been no concern about the format or the chronology of the

timetable. However, metric planners have stressed the need for an "industry

commitment date," which would represent an agreement by the bulk of the

construction community to participate in a voluntary but coordinated change,

based on an agreed timetable, so that individual entities can each play

their parts to effect the change in the best interests of the whole industry

and, especially, its clients.

116
The ANMC/CICC Timetable with its well-structured chronology of "action"

items and an indication of leadership responsibilities, is a practical

reminder of the need for "cooperation" between all sectors. Its focal

point, relative to which elasped times and targets can be measured, is the

"industry M-Day" —a conceptual date indicating the start of metric construction. The commitment in a timetable is not to specific dates, but rather

to phases or periods during which certain actions are expected to occur.

The individual industry segment, group, or organization, therefore, can phase into the overall time scale as and when it is most advantageous from

a technical and/or economic point of view.

8 . A International Precedent in Construction Metrication and Program Timing

Table 8-1 provides a summary of the approaches and time factors in metric

conversion in the construction industries of Britain, South Africa, Australia, and Canada. Even though industry size and structure differ from the

United States, the respective approaches and accomplishments are of interest. Metric planning, as a management exercise with technical overtones,

was basically the same in all countries, with each nation except Britain

learning from the precedent of others. In general, a period of 3 to 4 years to M-Day was found to be adequate to carry out the key activities

and, at the same time, maintain momentum.

8.5 A Model for the Achievement of a Decision on Construction Metrication

Responses to metrication vary from "let's stop talking and get it over and

done with" to "let's defer it until there is an absolute necessity to

change," with the bulk of the industry covering a middle ground of willingness to convert "if everyone else does." In the construction community,

the strongest advocacy has come from designers, who can foresee significant

gains in productivity, and the codes and standards sector, in which designers are heavily represented as professional decision-makers. Both groups

deal almost exclusively with "software." Except for certain groups which

can see very tangible benefits in a change, manufacturers, distributors,

contractors, and labor have preferred to defer a commitment.

It is widely recognized that the construction community cannot accomplish

a definite response to the metric issue without cooperation and involvement of the key sectors and major parties that make up the industry. The

principal purpose of the NIBS Metric Symposium is to provide a forum for the

"objective" examination of metric ' issues in the construction industries

without letting those in favor or those opposed dominate—and then to

develop suitable industry-wide strategies for future action.

Unlike other activities in the construction industry, metric conversion is

not an oft repeated activity which can be precisely designed, accurately

estimated in terms of cost or time, and carried out as a matter of routine.

It is the most difficult assignment the industry has faced for a long time.

It is an assignment that cannot be faced unilaterally by individual sectors

of the construction community, but rather needs to be undertaken by all or

117
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none. Therefore, it challenges the industry's ability to cooperate which,

in itself, has been difficult to accomplish in the past. By its very nature

as a new, untried, one-off exercise, metrication engenders resistance by

some, and concern by many. It is up to the industry, collectively, to assess and decide on the claims made both for and against the change.

This paper offers a model which might be used in the analysis leading up to

a decision by the construction community on whether or not to commit itself

to a voluntary conversion to metric measurement and, if so, on what type

of program to develop and how to follow-through. The model in figure 8-2

shows five major steps in the decision process:

1. Study of Metric Issues and Concerns

2. Assessment of Benefits vs. Costs

3. Decision on Metric Conversion in Construction

4. Development of a Timetable for Conversion

5. Allocation of Responsibility for Program Implementation (National,

Industry Sector or Group, Individual Organization).

Much of the work has already been done. The key stage is item three, the

decision on metric conversion. There are no neutral options—in the event

of a "yes," the timing becomes the next step and overriding issue; and the

event of a "no," the industry will continue to adapt as it has done to

date

It must be noted that the "Timetable for Conversion" presented by the

Construction Industries Coordinating Committee of the American National

Metric Council was developed entirely by the private sector, based on consensus procedures and participation by representatives of nearly all

major groups in the construction community. Any alternative would duplicate

most of the work.

8 . 6 From Timetable to Implementation

If a time frame for metric conversion were to be endorsed by the

construction industries, actual metric activities would occur in the practical world of design, production, and construction. Industry associations

would have a major role to play by widely publicizing the timetable and its

implications for their particular constituency, by assisting with implementation issues or problems, and by guiding members in reaching common

responses during a transition. In addition to becoming information

resources, the industry associations may also engage in metric training

and/or familiarization activities.

Whereas metric "implementation" would occur at the task face—the local

level—an overall advisory mechanism at the national level would be highly

desirable to give guidance, provide for coordination between diverse

sectors, resolve problems or conflicts, and, generally monitor progress

or lack thereof. Ideally, the implementation phase should be coordinated

by a group that is representative of all segments of the industry and

respected by all segments. No compulsory powers would ever be required

119
gure 8-2: A Model for Metrication Decisions in the U.S. Construction

Industries

0>

STUDY OF METRIC ISSUES AND CONCERNS

TECHNICAL FACTORS ORGANIZATIONAL FACTORS EXTERNAL FACTORS SOFTWARE Standards

Tech. Data

HARDWARE

Products Equipment

MANAGEMENT

Organization

Planning

EDUCATION

Training

Familiarization

ACTIVITY

IN OTHER

SECTORS

INTER- NATIONAL

ACTIVITY

OPPORTUNITIES AND PROBLEMS FACTUAL DATA

OPINIONS LESSONS FROM ESTIMATES PRECEDENT

<

ROM I ITS

ASSESSMENT OF COSTS AND BENEFITS

COSTS OF GOING METRICCOSTS OF NOT GOING METRICBENEFITS OF GOING METRICSAVINGS BY NOT GOING METRIC

DECISION ON METRIC CONVERSION IN CONSTRUCTION

© <

^

>COMMITMENT>sN

| DEFERRAL \

r y e s j r n~o~~j—\

Continue to Adapt

as required

DEVELOPMENT OF CONVERSION TIMETABLE

ANMC/CICC

ANMC/

MODI CICCFIED OTHER

. 2 ALLOCATING RESPONSIBILITY FOR IMPLEMENTATION

CONSTRUCTION INDUSTRIES

INDUSTRY SECTORINDUSTRY GROUP INDIVIDUAL ORGANIZATION

120
by such a group (or committee), since its very strength would lie in its

advisory role. The alternative—not to have any overall guidance—would

almost certainly prevent a cost-effective metric conversion in the

construction industries.

At the sector level, supplementary committees would be needed to deal in more depth with specific implementation issues.

At the organizational level, planning for the change and its implementation

will vary with size. In general, the larger the organization, the more opportunity exists to benefit from a conversion by using it to introduce

variety reduction and rationalization of products, processes, and procedures; but, at the same time, the greater the chance of confusion if personnel is not properly briefed or trained. It is important that once a decision has been made to change to metric operations, a good metric climate and information flow be maintained both within and outside the

organization.

REFERENCES

1. Metric Conversion in the Construction Industries. . .Planning, Coordination and Timing; American National Metric Council, Washington, D.C.:

1980, 56 pages.

2. Standard Practice for Use of Metric (SI) Units in Building Design and

Construction, ASTM E621-78; American Society for Testing and Materials,

Philadelphia, PA; 1978, 36 pages.

3. AIA Metric Building and Construction Guide; Wiley Interscience , Inc.,

New York, NY; 1980; 154 pages.

4. Metric Practice Guide for Surveying and Mapping, American Congress

on Surveying and Mapping, Falls Church, VA; March 1978; 12 pages.

121

PART 9 - METRIC BIBLIOGRAPHY

9. 1 Government Issuances

Bibliography on Metric Conversion , Metric Commission Canada, Ottawa,

Canada; Revision January 1980.

Conversion to the Metric System of Weights and Measures , (hearings

before the Subcommittee on Science, Research and Development of the

Committee on Science and Astronautics, House of Representatives, 93rd

Congress, 1st Session, No. 3, March 19-22, and May 9-10, 1973), U.S.

Committee on Science and Astronautics, Superintendent of Documents,

U.S. Government Printing Office, Washington, D.C.; 1973.

Getting a Better Understanding of the Metric System ~ Implications If

Adopted by the United States , Publication No. CED-78-128, Comptroller

General of the United States, U.S. General Accounting Office, Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.;

October 1978. Chapter 16 - A Delimma for the Construction Industry.

Getting a Better Understanding of the Metric System - Implications If

Adopted by the United States - Executive Summary , Publication No. CED78-128A, Comptroller General of the United States, U.S. General Accounting Office, Superintendent of Documents, U.S. Government Printing

Office, Washington, D.C.; October 1978.

International System of Units , NBS Special Publication 330, National

Bureau of Standards, Superintendent of Documents, U.S. Government

Printing Office, Washington, D.C.; 1977.

International Trends and Developments of Importance to the Metrication

Plans of the U.S. Construction Community , NBS Technical Note 976,

National Bureau of Standards, Washington, D.C.; June 1978.

Metrication and Dimensional Coordination - A Selected Bibliography , NBS Special Publication 458, National Bureau of Standards, Washington,

D.C. ; April 1977.

Metrication in Building , Excerpt from "Building Research" (Journal of

the) BRAB Building Research Institute, National Research Council,

Washington, D.C; Volume 10, No. 1, January/March 1974; pp. 1-44.

Metrication in Building Design, Production and Construction , NBS Special

Publication 530, National Bureau of Standards, Washington, D.C;

September 1978.

Metric Conversion , (Hearings before the Committee on Commerce, U.S.

Senate, 92nd Congress, 2nd Session on S. 2483, February 29 and March 1,

1972, Serial No. 92-64). U.S. Committee on Commerce, Superintendent of

Documents, U.S. Government Printing Office, Washington, D.C; 1972.

123
Metric Dimensional Coordination - The Issues and Precedent , NBS Special

Publication 504, National Bureau of Standards, Washington, D.C.;

Feburary 1973.

Metric Laws and Practices in International Trade - A Handbook for U.S.

Exporters, U.S. Department of Commerce, Superintendent of Documents,

U.S. Government Printing Office, Washington, D.C.; 1976.

Policy on Publication of Plane Coordinates , U.S. Department of Commerce,

National Oceanic and Atmospheric Administration, National Ocean Survey,

National Geodetic Survey, FR Dec 77-8847, Washington, D.C.; March 1977.

Preferred Metric Units for General Use by the Federal Government, NBS LC

1098, Interagency Committee on Metric Policy, Office of Weights and

Measures, National Bureau of Standards, Washington, D.C.; November 1978.

Recommended Practice for the Use of Metric (SI) Units in Building Design

and Construction , NBS Technical Note 938, National Bureau of Standards,

Washington, D.C.; December 1978.

State Metric Status , A series of five reports, Northeastern Region,

Southern Region, Near-Western Region, Mid-Western Region, Far-Western

Region , U.S. Metric Board, Arlington, VA; September 1980.

The Selection of Preferred Metric Values for Design and Construction , NBS Technical Note 990, National Bureau of Standards, Washington, D.C.;

December 1978.

Uniform Metric System Procedure Act , National Conference of Commissioners

on Uniform State Laws, Chicago, IL; 1979.

U.S. Metric Study (Comprehensive Report): A Metric America: A Decision

Whose Time Has Come , NBS Special Publication 345, National Bureau of

Standards, Washington, D.C.; August 1971.

U.S. Metric Study (Interim Reports), National Bureau of Standards,

Washington, D.C.

International Standards, NBS Special Publication 345-1, December 1970.

Federal Government: Civilian Agencies , NBS Special Publication 342-2,

July 1971.

Commercial Weights and Measures , NBS Special Publication 345-3, July

1971.

The Manufacturing Industry , NBS Special Publication 345-4, July 1971.

The Consumer , NBS Special Publication 345-7, July 1971.

International Trade , NBS Special Publication 345-8, August 1971.

A History of the Metric System Controversy in the United States , NBS Special Publication 345-10, August 1971.

Engineering Standards , NBS Special Publication 345-11, July 1971.

Testimony of Nationally Representative Groups , NBS Special

Publication 345-12, July 1971.

124
Weights and Measures Standards of the United States ~ A Brief History , National Bureau of Standards, Washington, D.C.; 1976.

9. 2 Industry and Association Issuances

Analysis and Design of Slab Systems - computer program, Portland Cement

Association, Skokie, IL; 1971.

Aluminum Standards and Data - 1978 Metric SI , The Aluminum Association,

Inc., Washington, D.C; 1978.

AISI Metric Practice Guide, 3rd Edition, Communication and Education

Service Department, American Iron and Steel Institute, Washington, D.C,

1978.

American Society of Photogrammetry Usage of the International System of

Units , American Society of Photogrammetry, Falls Church, VA; 1978.

Design Criteria for Lighting Interior Living Spaces , Illuminating Engineering Society, New York, NY; 1979.

Guidelines for Metric Data in Standards for Valves, Flanges, and Fittings , (S/FP-86), Manufacturers Standardization, Society of the Valve and Fittings Industry, Arlington, VA.

Lumber and Wood Products Metric Planning Package , A Status Report by

Lumber and Wood Products Sector Committee, ANMC, National Forest Products

Association, Washington, D.C; Mid-1978.

Measurement of Fire Phenomena , Society of Fire Protection Engineers,

Boston, MA; Draft February 1978.

"Metrication - A Concrete Opportunity," Hans J. Milton; ACI Journal ; American Concrete Institute, Detroit, MI; November 1977; pp. N13-N21.

Metric Design Handbook , (SP-20D), Portland Cement Association; Canadian

Portland Cement Association, 116 Albert Street, Ottawa, Ontario, Canada.

Metric Guide for Mechanical Design and Drafting , Frederick T. Gutmann,

Industrial Press, Inc., New York, NY; 1978.

Metric Practice Guide for Surveying and Mapping , American Congress on Surveying and Mapping; Falls Church, VA; March 1978.

Metric Practice Guide for Welding Industry , AWS Al,l-7x; by Metric

Practice Committee, American Welding Society, Miami, FL; October 1978.

Metric Practice Guide (SI) - Units and Conversion Factors for the Steel

Industry 1976 , American Iron and Steel Institute, Washington, D.C; 1976.

Metric Zoning Guide , Karen White, American Planning Association,

Washington, D.C; 1979.

125
The Meter-Part of New Panorama, "Gunther Greulich, Proceedings of

American Congress on Surveying and Mapping, St. Louis, MO; March 1974.

Use of Customary and SI (Metric) Units: ASAE Engineering Practice , ASAE

EP 285.4 (including preferred units), American Society of Agricultural

Engineers, St. Joseph, MI.

"Use of Metric System in Meter and Bounds Surveys," Gunther Greulich,

Proceedings of American Congress on Surveying and Mapping, Washington,

D.C. ; September 1974.

Weyerhaeuser Metric Practice Guide , 3rd Edition, Weyerhaeuser Company,

Tacoma, WA, 1980.

9. 3 Handbooks and General Information Issuances

AIA Metric Building and Construction Guide , Wiley Interscience , Inc.,

New York, NY; 1980.

"Metrication: Controversy and Opportunity," Thomas Clark Tufts;

Progressive Architecture , March 1979; reprints available from Reinhold

Publishing Company, Inc.

Metric Conversion Handbook , Marvin H. Green, Chemical Publishing Company,

New York, NY; 1980.

Metric Units in Engineering - Going SI , Cornelius Wandmacher, Industrial

Press, Inc., New York, NY, 1978.

Metric Yearbook , 1975-1980 Editions, J. J. Keller and Associates, Inc.,

Neenah, WI; 1975-1980.

"Our Metric Future," Hans J. Milton, The Construction Specifier ; February 1979; reprints available from Construction Specifications

Institute, Washington, D.C.

Standards Handbook for Metric Machinery Fasteners , J. M. Stockbridge,

The Standards Handbook Company, Flint, MI; 1977.

"Subdivision Design in Meters," Gunther Greulich, Journal of the Boston

Society of Civil Engineers Section, American Society of Civil Engineers,

Vol. 66, No. 4, Boston, MA; 1979.

The Modernized Metric System ... Explained , J. J. Keller and Associates,

Inc., Neenah, WI; (undated).

9. 4 Standards Organizations Issuances

American National Standard Alloy and Temper Designation Systems for

Aluminum , ANSI H35. 1 (M) 1978; American National Standards Institute,

New York, NY; 1978-

126
American National Standard Dimensional Tolerances for Aluminum Mill

Products , ANSI H35. 2(M)-1978; American National Standards Institute,

New York, NY; 1978.

ASTM Standard for Metric Practice , ASTM E380-79, American Society for

Testing and Materials, Philadelphia, PA; 1980.

ASHRAE Metric Guide for Heating, Refrigerating, Ventilating and

Air-Condi tioning , Second Edition, American Society of Heating,

Refrigerating and Air-Conditioning Engineers, New York, NY.

American Society of Plumbing Engineers, Data Book, Volume I - Fundamentals of Plumbing Design, 1979/80; American Society of Plumbing

Engineers, Sherman Oaks, CA.

American Society of Plumbing Engineers, Data Book, Volume II - Special

Plumbing Systems Design, 1977/78; American Society of Plumbing Engineers,

Sherman Oaks, CA.

American Society of Plumbing Engineers Solar Energy System Design , American Society of Plumbing Engineers, Sherman Oaks, CA. ; 1980.

IEEE Standard for Metric Practice , IEEE Std. 268, Institute of Electrical

and Electronics Engineers, New York, NY; 1979.

Metrication - Managing the Industrial Transition , ASTM Special Technical

Publication 574, R. G. Liptai and J. W. Pearson, American Society for

Testing and Materials, Philadelphia, PA; 1975.

Preferred SI (Metric) Units: ASAE Engineering Practice , ASAE EP 285.4

(including preferred units), John H. Addington, Compressed Air and Gas

Institute, Cleveland, OH.

Standard Practice for the Use of Metric (SI) Units in Building Design

and Construction , ASTM E621-78, American Society for Testing and

Materials, Philadelphia, PA; 1978.

In addition, the following construction related metric standards are published by the American Society for Testing and Materials (ASTM),

Philadelphia, PA.

A109M-77 Specification for Steel, Carbon, Cold-Rolled Strip

A325M-79 Specification for High-Strength Bolts for Structural Joints

A501M-77 Specification for General Requirements for Wire Rods and

Coarse Round Wire, Carbon Steel

A568M-74 Specification for Steel, Carbon and High-Strength Low-Alloy

Hot-Rolled Sheet, Hot-Rolled Strip, and Cold-Rolled Sheet,

General Requirements

127
A615M-7 9 Specification for Deformed and Plain Billet-Steel Bars for

Concrete Reinforcement

A623M-78 Specification for General Requirements for Tin Mill Products.

A624M-79 Specification for Tin Plate, Single-Reduced Electrolytic.

A626M-79 Specification for Tin Plate, Double-Reduced Electrolytic

A635M-77 Specification for Steel Sheet and Strip, Carbon (0.15 percent

max), Hot-Rolled Commercial Quality, Heavy-Thickness Coils

(Formerly Plate)

A682M-77 Specification for Steel, High-Carbon, Strip, Cold-Rolled,

Spring Quality, General Requirements

A749M-77 Specification for Steel, Carbon, and High-Strength, Low-Alloy,

Hot-Rolled Strip, General Requirements

B133M-80 Specification for Copper Rod, Bar, and Shapes

B139M-80 Specification for Phosphor Bronze Rod, Bar, and Shapes

B140M-80 Specification for Copper-Zinc-Lead (Leaded Red Brass or Hardware Bronze), Rod, Bar and Shapes

B209M-80 Specification for Aluminum-Alloy Sheet and Plate

B210M-80 Specification for Aluminum-Alloy Drawn Seamless Tubes

B211M-79 Specification for Aluminum-Alloy Bar, Rod, and Wire

B221M-79 Specification for Aluminum-Alloy Extruded Bars, Rods, Wire,

Shapes, and Tubes

B247M-80 Specification for Aluminum-Alloy Die and Hand Forgings

B248M-80 Specification for General Requirements for Wrought Copper

and Copper-Alloy Plate, Sheet, Strip, and Rolled Bar

B249M-79 Specification for General Requirements for Wrought Copper and

Copper-Alloy Rod, Bar, and Shapes

B250M-79 Specification for General Requirements for Wrought Copper-Alloy

Wire

B251M-79 Specification for General Requirements for Wrought Seamless

Copper and Copper-Alloy Tube

B557M-79 Tension Testing Wrought and Cast Aluminum- and Magnesium-Alloy

Products

128
B666M-80 Practice for Identification Marking of Aluminum Products

C14M-80 Specification for Concrete Sewer, Storm Drain, Culvert Pipe

C76M-80 Specification for Reinforced Concrete Culvert, Storm drain

and Sewer Pipe

C118M-80 Specification for Concrete Pipe for Irrigation or Drainage

C361M-78 Specification for Reinforced Concrete Low-Head Pressure Pipe

C412M-80 Specification for Concrete Drain Tile

C443M-80 Specification for Joints for Circular Concrete Sewer and

Culvert Pipe, Using Rubber Gaskets

C444M-80 Specification for Perforated Concrete Pipe

C478M-80 Specification for Precast Reinforced Concrete Manhole Sections

C497M-80 Methods of Testing Concrete Pipe, Sections, or Tile

C505M-80 Specification for Nonreinf orced Concrete Irrigation Pipe with

Rubber Gasket Joints

C506M-80 Specification for Reinforced Concrete Arch Culvert, Storm

Drain, and Sewer Pipe

C507M-80 Specification for Reinforced Concrete Elliptical Culvert,

Storm Drain, and Sewer Pipe.

C654M-80 Specification for Porous Concrete Pipe

C655M-80 Specification for Reinforced Concrete D-Load Culvert, Storm

Drain, and Sewer Pipe

C789M-78 Specification for Precast Reinforced Concrete Box Sections for

Culverts, Storm Drains, and Sewers

C850M-78 Precast Reinforced Concrete Box Sections for Culverts, Storm

Drains and Sewers with less than 0.6 m of Cover Subjected to

Highway Loadings

C877M-80 Specification for External Sealing Bands for Noncircular

Concrete Sewer, Storm Drain, and Culvert Pipe

E621-78 Standard Practice for the Use of Metric (SI) Units in Building

Design and Construction

E713-80 Scales for Metric Building Drawings

129
F467M-79 Specification for Nonferrous Nuts for General Use

F468M-79 Specification for Nonferrous Bolts, Hex Cap Screws, and Studs

for General Use

9.5 American National Metric Council Issuances

Managing Metrication in Business and Industry , American National Metric

Council, Marcel Dekker, Inc., New York, NY; 1976.

Metrication for the Manager , John T. Benefict, American National Metric

Council, Washington, D.C.; September 1977.

Metric Conversion in the Construction Industries ... Planning,

Coordination and Timing , American National Metric Council, Washington,

D.C.; 1980.

Metric Conversion in the Metals Industry (Metal Products - Ferrous and

Non-Ferrous , 3rd. Edition, American National Metric Council, Washington,

D.C. ; April 1979.

Metric Conversion Paper #4, Metrication ~ Problems and Opportunities , American National Metric Council, Washington, D.C; 1974.

Metric Conversion Paper #12, Metrication of Computer Applications , American National Metric Council, Washington, D.C; 1976.

Metric Conversion Paper #13, Metrication at Dunlop , American National

Metric Council, Washington, D.C; 1976.

Metric Conversion Paper #14, A Selected Bibliography for Metrication

in Business and Industry , American National Metric Council, Washington,

D.C; 1977.

Metric Conversion Paper #15, Metrication: What Needs to be Done - ANMC

Before the U.S. Metric Board on 18 August 1978 , American National Metric

Council, Washington, D.C; 1978.

Metric Editorial Guide , Third Edition, American National Metric Council,

Washington, D.C; 1978.

SI Training Guide , American National Metric Council, Washington, D.C;

1979.

130
PART 10 - APPENDICES

APPENDIX 1 - Extracts from NBS SP 345-12, U.S. Metric Study Interim Report,

Testimony of Nationally Representative Groups

Page 4 of General Summary

THE CONSTRUCTION INDUSTRY

The construction industry is extremely complex and any conversion

would require careful coordination in order to minimize problems. Most

groups see little direct benefit to the industry from conversion, but many feel that it would present an ideal opportunity to advance the concept of modular

construction and thus achieve important cost savings. A special problem for the industry would be the need to repair and remodel existing structures which would require added inventories to be maintained for many years.

Page 76 ff. - Details of Construction Industry Responses

VII. CONSTRUCTION

A SUMMARY OF INPUTS

The construction inputs were obtained with the special assistance of the Construction Affairs Committee of the Chamber of Commerce of the

United States. Inputs were received from 26 construction related groups. A majority of those groups (ten) expressing an opinion feel that metrication is inevitable and/or desirable. Only two groups are opposed to metrication; 14 either express no opinion or state the use of measurement systems

does not affect their activities. Almost all groups expressing an opinion on a preferred method of conversion indicate that any such program should be carried out only under a

nationally coordinated program. Some want a mandatory program and many

suggest that a Federal agency take over responsibility for coordination. A

10-year transition time is commonly preferred, with the first 5 years used in converting codes, standards, and catalogs.

Cost and Benefits of Conversion

There is some resistance to change, usually based on estimates of transi- tion costs with no foreseeable benefits. Many feel that conversion costs would be moderate, and once behind them the simplicity of metric usage

would bring continuing savings, opportunities for more modular construction, and increased exports.

Transition costs would be less than for manufacturing industries since

most equipment changes could be made by adjustments or by normal maintenance in 1 or 2 years. Some added costs would be anticipated during

transition from the necessary accelerated revision of codes, standards, an d

131
design tables: added inventories causing some mix-ups at the job site; and some worker inefficiency while adjusting to metric sizes. Training would not be a serious problem for the construction industry.

The changeover would require new thinking, and "unlearning" of longestablished relationships. Vocational and apprentice schools would have to change instruction to use metric units, but young workers entering the field with metric training would find measurements and calculations easier to make.

Some problems would be faced, during and after conversion, in repairing

older structures built to customary standards. Dual inventories would have

to be maintained on some materials for many years, and a variety of adapters

would have to be stocked.

Modular Construction

More than half of the industry reports comment on the opportunity offered

by metrication to advance the concept of modular construction and achieve

important cost savings. Unified codes could reduce the number of sizes and

simplify the fitting of components together on the job. Uniformity would

reduce intermixing and on-site cutting, and save construction time. In addition, the use of metric modules would provide more opportunities for exchange of materials and test data abroad.

Metric standards for wallboard and plywood panels are only slightly

smaller than our 4 by 8 foot standard. Producers could change over to metric

sizes by merely adjusting machinery. Metric cement block dimensions are close to present U.S. sizes, with about a 3/8 inch difference in thickness.

Since molds have a relatively short life, conversion of the machinery could

take place during normal replacement. A major concern for all such building

products manufacturers during any conversion process would be the need to continue to supply products made to inch standards at the same time as new

metric-sized products are being produced.

Other Items

The conversion of land title descriptions to metric units is suggested only on a "go forward" basis, at the time property changes hands. No useful pur- pose would be served by converting existing records. Maps could be converted at the time of normal up-dating.

The experience of the construction industry in England, which is taking a leading role in metrication there, is cited by several trade associations as a good guide to the procedures which should be followed. All building construction in England will become metric by 1972, 7 years after the start of

their metrication program.

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138
U.S. METRIC STUDY— AGENDA FOR CONSTRUCTION INDUSTRY CONFERENCE

CONSTRUCTION INDUSTRY CONFERENCE

Sponsored by the

U.S. Department of Commerce, National Bureau of Standards,

Gaithersburg, Maryland, October 5-6, 1970

Monday. October 5

9:30-10:15 Opening Session Chairman Daniel V. DeSimone. Director, U.S

Metric Study

Welcome—"The National Bureau of Standards and Its Responsibilities Under the Metric Study Act"—Lawrence M. Kushner. Deputy Director. National Bureau of Standards "The Construction Industry and the Metric System"—Douglas Whitlock; Whitlock, Markey & Tait: member, Metric System Study

Advisory Panel

10:30-12:30 Session One: Building Design, Codes, and Standards

Participants: American Institute of Architects Consulting Engineers Council of the U.S.A.

Building Officials Conference of America, Inc.

International Conference of Building Officials 1:30- 4:30 Session Two: Building Materials. Production and Sales Participants: American Concrete Institute National Concrete Masonry Association

Structural Clay Products Institute National Forest Products Association

California Redwood Association American Plywood Association

Tuesday, October 6

9:30-11:15 Session Three: General Contractors and Subcontractors

Participants: Associated General Contractors of America

National Constructors Association Gypsum Drywall Contractors International International Association of Wall and Ceiling Contractors

11:15-12:00 Session Four: Building Services

Participants: National Electrical Contractors Association. Inc. Air Conditioning and Refrigeration Institute

1:00- 2:00 Session Five: Home Builders and Home Manufacturers

Participants: National Association of Home Builders Mobile Home Manufacturers Association

2:15- 4:30 Session Six: Land Services and Heavy Construction

Participants: American Land Title Association American Society of Civil Engineers

American Road Builders Association

139

APPENDIX 2 - Listing of Organizations Contacted for Information Included

in Part 2 - "Current Activities in Professional and IndustryGroups and State Government Policies, Metric Committees or Coordinators, Metric Actions."

Construction Related National Associations

Air Conditioning and Refrigeration Institute

Aluminum Association, The

American Association of Cost Engineers

American Concrete Institute

American Concrete Pipe Institute

American Congress on Surveying and Mapping

American Consulting Engineers Council

American Geophysical Union

American Hospital Association

American Institute of Architects

American Institute of Real Estate Appraisers

American Insurance Association

American Iron and Steel Institute

American Land Title Association

American National Standards Institute

American Plywood Association

American Society of Engineering Education

American Society for Testing and Materials

American Society of Building and Construction Inspectors

American Society of Civil Engineers

American Society of Heating, Refrigerating, and Air-Conditioning

Engineers

American Society of Landscape Architects

American Society of Lighting Designers

American Society of Mechanical Engineers

American Society of Photogrammetry

American Society of Planning Officials

American Society of Plumbing Engineers

American Society of Safety Engineers, Inc.

American Society of Sanitary Engineering

Associated General Contractors of America

Association of Wall and Ceiling Industries, International

Brick Institute of America

Building Officials and Code Administrators International, Inc.

Business and Institutional Furniture Manufacturers Association

Carpenters and Joiners of America, United Brotherhood of

Cast Iron Soil Pipe Institute

Concrete Reinforcing Steel Institute

Construction Specifications Institute, The

Copper Development Association, The

Council of American Building Officials

Dcor and Hardware Institute

141
Gas Appliance Manufacturers Association

Gypsum Association

Hardwood Plywood Manufacturers Association

Illuminating Engineering Society

Institute of Business Designers

Institute of Real Estate Management

Interior Design Educators Council

International Association of Bridge, Structural, and Ornamental Iron

Workers

International Association of Plumbing and Mechanical Officials

International Brotherhood of Electrical Workers

International Conference of Building Officials

International Masonry Institute

International Real Estate Federation, American Chapter

Laborers International Union of North America

Lead Industries Association

Manufactured Housing Institute

Mechanical Contractors Association

Metal Building Dealers Association

National Academy of Code Administration

National Asphalt Pavement Association

National Association of County Recorders and Clerks

National Association of Plumbing-Heating-Cooling Contractors

National Association of Home Builders

National Association of Home Manufacturers

National Association of Realtors

National Concrete Masonry Association

National Electrical Contractors Association

National Electrical Manufacturers Association

National Environmental Systems Contractors Association

National Fire Protection Association

National Forest Products Association

National Insulation Contractors Association, Inc.

National Lumber and Building Materials Dealer's Association

National Society of Professional Engineers

National Utility Contractors Association

Portland Cement Association

Prestressed Concrete Institute

Producer's Council, The

Realtors National Marketing Institute

Red Cedar Shingle and Handsplit Shake Bureau

Sheet Metal and Air-Conditioning Contractors National Association, Inc.

Society of American Registered Architects

Society of Industrial Realtors

Society of Plastics Industry

Society of Real Estate Appraisers

Southern Building Code Congress International, Inc.

Thermal Insulation Industrial Council

Tile Contractors Association of America, Inc.

Tile Council of America

Truss Plate Institute

142
Underwriters' Laboratories, Inc.

Women's Council of Realtors

Construc tion Related Individual Companies

American Standard/U. S. Plumbing Products

American Telegraph and Telephone

Armstrong Cork Company

T.R. Arnold and Associates, Inc.

Babcock and Wilcox

Bechtel Power Corporation

Bethlehem Steel Corporation

Bliss Steel Products

Boise-Cascade Housing Division

Braun and Wieder Construction Company

Buick Motor Division

Cahner's Publishing Company

Carrier International Corporation

Certain-Teed Products Corporation

Fleetwood Enterprises, Inc.

GAP Corporation

W.R. Grace and Company

Green Construction Company

Halstead and Mitchell

IBM Corporation

Johns-Manville World Headquarters

Koppers Company, Inc.

Lockhard Manufacturing Company

McGraw-Hill Information Systems

Mobil Research and Development Corporation

Monsanto Company, The

PPG Industries

Quaker-Maid, A Tappan Division

Smith, Hinchman and Grylls Associates

Structures Unlimited, Inc.

Tishman Research Corporation

Turner Construction Company

Union Carbide Corporation

U.S. Gypsum

Weyerhaeuser Company

143
NBS-114A (rev. 2-80) U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO. NBS SP 598

2. Performing Organ. Report No 3. Publ ication Date

October 1980

4. TITLE AND SUBTITLE

Metric Conversion in the Construction

Industries - Technical Issues and Status

5. AUTHOR(S)

Hans J. Milton and Sandra A. Berry

6. PERFORMING ORGANIZATION (If joint or other than NBS. see instructions)

NATIONAL BUREAU OF STANDARDS

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WASHINGTON, D.C. 20234

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Construction industries; dimensional coordination; metric bibliography; metric

conversion timetable; metric decision; metric product sizes; metric system (SI)

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