Reference

f *

NBS

Publi - cations NBS TECHNICAL NOTE 922

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

Economic Analysis ol

Experimental Lead Paint

Abatement Methods:

Phase I

QC

100

.115753

no. 922

1976
NATIONAL BUREAU OF STANDARDS

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- Located at Boulder. Colorado 80302.
Bational Bureau ol Sujuou/uj

S£P 2 3 m, Economic Analysis of Experimental

Lead Paint Abatement Methods: Phase I

r~>

Q N Robert E. Chapman

\\\h

Center for Building Technology

Institute for Applied Technology

National Bureau of Standards

Washington, D.C. 20234

Sponsored by the

Office of Policy Development and Research Department of Housing and Urban Development

Washington, D.C. 20410

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U.S. DEPARTMENT OF COMMERCE, Elliot L. Richardson, Secretary

Edward O. Vetter, Under Secretary

Dr. Betsy Ancker-Johnson, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director

Issued September 1976
Library of Congress Catalog Card Number: 76-600046

National Bureau of Standards Technical Note 922

Nat. Bur. Stand. (U.S.), Tech. Note 922,112 pages (Sept. 1976) CODEN: NBTNAE

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1976

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 (Order by SD Catalog No. C13.46:922). Stock No. 003-003-01668-3 Price $1.75

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PREFACE

This research was conducted under the sponsorship of the Department of Housing and Urban Development as a supporting economics effort

for the Office of Housing and Building Technology, in the Center for

Building Technology, Institute for Applied Technology, National Bureau

of Standards. This report, prepared by the Building Economics Section,

analyzes the direct cost figures for lead-based paint abatement collected during Phase I of the Experimental Hazard Elimination Program

(EHEP) and provides public and private decision makers with a procedure

for estimating the direct costs of lead-based paint abatement.

Appreciation is extended to Dr. Harold E. Marshall, Building Economics Section, who reviewed the economic aspects of this paper. Appreciation is also extended to Dr. Stephen F. Weber, Building Economics

Section, and Mr. Harvey W. Berger, Office of Housing and Building Technology, who provided useful suggestions for improving the treatment of

certain topics in this paper. Special appreciation is extended to Dr.

Joseph G. Kowalski, Building Economics Section, for his valuable assistance throughout the preparation of the paper.

in
Economic Analysis of Experimental

Lead Paint Abatement Methods: Phase I

Robert E. Chapman

Public and private concern about the potential for lead poisoning

in children due to the ingestion of lead-based paint chips has resulted

in a Federally sponsored program to develop technologies by which the

lead-based paint hazard may be eliminated from the nation's housing.

Through this program lead-based paint abatement techniques were tested

in field deleading operations conducted in Washington, D.C., and Atlanta, Ga. The program also focused on the collection of data on the

direct costs of labor, materials and special equipment associated with

these abatement techniques.

This report provides a statistical analysis of this direct cost

data by abatement technique and building component (i.e., walls, doors,

door frames, windows and frames, and miscellaneous trim). Abatement

techniques are ranked according to their relative costs. A cost model

is developed for each ranking which identifies the key factors which

affect direct cost and provides a framework whereby direct costs may be

estimated. Recommendations are made for further refinement of the

model; a methodology through which the optimal combination of lead-based

paint abatement techniques can be identified is also outlined.

Key words: Abatement; building economics; building materials; economic

analysis; housing; lead-based paint; lead poisoning.

IV
EXECUTIVE SUMMARY

Lead poisoning in children through the ingestion of lead-based

paint chips is a serious health problem in American housing. Interest

in how to eliminate the lead-based paint hazard from housing has lead to

the passage of the "Lead-Based Paint Poisoning Prevention Act" (PL 91-

695) in January, 1971. Through this Act Congress has delegated to the

Department of Housing and Urban Development (HUD) the leadership role in

the research and development of technologies by which the lead-based

paint poisoning hazard may be eliminated from the nation's housing. One

part of HUD's research role has been the formulation of the Experimental

Hazard Elimination Program (EHEP). This program is intended to aid in

the identification of potential lead-based paint abatement techniques

and to gather data on the direct costs associated with these techniques.

An economic model is needed to determine the efficiency of the potential

lead-based paint abatement strategies.

This study analyzes the direct cost data collected in two cities,

Washington, D.C., and Atlanta, Ga., during Phase I of EHEP. Additional

cost data, which will facilitate the analysis of variations both in

direct costs and a contractors' bid price, are currently being collected

in Boston, Mass., under Phase II of EHEP. The Phase I direct costs

associated with each abatement technique are analyzed by building component (walls, doors, door frames, windows and frames, and miscellaneous

trim). The per unit direct costs (per square foot, per item, per linear

foot) are presented as are statistical analyses of per unit direct costs

at the dwelling unit level. The various abatement techniques are then

ranked according to their per unit direct costs. These categories

(rankings) are so designed that every abatement technique in the same

category has comparable per unit direct costs whereas those in another
category have significantly higher or lower per unit direct costs. For

example, there were 9 different wall abatement techniques used during

Phase I of EHEP with average per unit direct costs varying from $0.20 to

$1 .65 per square foot. When these abatement techniques were tested to

see if any significant differences in per unit direct costs existed, 4

categories resulted. The 4 categories in increasing order of per unit

cost were (1) painting techniques, (2) mixed techniques (plastering,

wall board and fabric coverings), (3) plastering techniques, and (4)

paneling techniques. Furthermore, in addition to similarity of costs

within a category, some of the abatement techniques also exhibited

similarities in the method of application (e.g., the various painting

techniques included in category 1). Cost models were then formulated

for each category, within which those variables which have the greatest

impacts on direct cost are identified and the impacts quantified.

The cost models presented in this report have been formulated in

such a manner that variations in per unit direct cost due to the quantity of surface abated, prevailing wage rates, the productivity of

labor, or the size of the abatement contract are captured. Since this

method of cost estimating addresses the major sources of variation in

direct cost, it also captures differences in direct costs due to regional effects. Thus most of the cost models may be used with confidence in most demographic regions of the nation as a means whereby

decision makers can estimate the direct costs of lead-based paint abatement.

An alternative cost-estimating method based on the cost models

developed with the Phase I EHEP data is also discussed which permits the

prediction of per unit direct cost through the use of a graphical procedure.

VI
Since many of the techniques used for lead-based paint abatement

are useful in the rehabilitation or renovation of housing, the cost

models developed in this report can also provide a reliable procedure

for obtaining estimates for the direct costs of certain aspects of

rehabilitation.

A comprehensive cost estimating model which could aid in the identification of that combination of lead-based paint abatement techniques

which are economically optimal is shown to require a broader view of

costs than that provided by direct costs. It is demonstrated that total

project costs, which include the contractors' markup, should be considered to ensure that those strategies for lead-based paint abatement

which are least cost will be selected.

V1X
TABLE OF CONTENTS

Page

PREFACE i±i

ABSTRACT iv

EXECUTIVE SUMMARY v

LIST OF FIGURES xi

LIST OF TABLES . . . . xi

SI CONVERSION UNITS xiii

1

.

INTRODUCTION 1

1.1 BACKGROUND (THE EXPERIMENTAL HAZARD ELIMINATION PROGRAM (EHEP)) 1

1.2 PURPOSE 4

1.3 SCOPE AND APPROACH 4

2. DESCRIPTION OF PHASE I EHEP 6

2.1 SITE SELECTION 6

2.1.1 THE SELECTION OF WASHINGTON, D.C 6

2.1.2 THE SELECTION OF ATLANTA, GEORGIA 7

2.2 DWELLING UNIT SELECTION 7

2.2.1 DWELLING UNIT SELECTION IN WASHINGTON, D.C. . . 9

2.2.2 DWELLING UNIT SELECTION IN ATLANTA, GEORGIA . . 10

2.3 ABATEMENT TECHNIQUE SELECTION 11

2.4 ASSIGNMENT OF ABATEMENT TECHNIQUES TO THE STOCK OF

DWELLING UNITS 14

2.5 FORMAT AND METHODOLOGY FOR COST DATA COLLECTION .... 15

3. THEORETICAL ANALYSIS OF BUILDING COMPONENT COST DATA .... 22

3.1 STATISTICAL TECHNIQUES UTILIZED 23

3.2 COMPARISON AND RANKING 26

3.3 ESTABLISHMENT OF FUNCTIONAL RELATIONSHIPS 29

3.4 GRAPHICAL COST ESTIMATING PROCEDURE 33

3.5 COMPUTATIONAL COST ESTIMATING PROCEDURE 38

vin
Page

4. RESULTS OF DATA ANALYSIS BY BUILDING COMPONENT AND ABATEMENT TECHNIQUE 41

4.1 WALL ABATEMENT TECHNIQUES 45

4/2 DOOR ABATEMENT TECHNIQUES 50

4.3 DOOR FRAME ABATEMENT TECHNIQUES 56

4.4 WINDOW AND WINDOW FRAME ABATEMENT TECHNIQUES 61

4.5 ABATEMENT TECHNIQUES FOR MISCELLANEOUS TRIM COMPONENTS 67

5. SUMMARY AND RECOMMENDATIONS FOR FURTHER RESEARCH 72

5.1 SUMMARY 72

5.2 RECOMMENDATIONS FOR FURTHER RESEARCH 74

APPENDIX A: DESCRIPTION OF ABATEMENT TECHNIQUES 76

A.l PAINT REMOVAL METHODS 76

A. 1.1 SOLVENT-BASED PAINT REMOVERS 76

A. 1.2 HAND SCRAPING 77

A. 1.3 ELECTRICAL HEAT GUN 77

A. 1.4 INFRA-RED HEAT DEVICE 78

A. 1.5 PROPANE TORCH 78

A. 1.6 DIP TANK METHOD 79

A. 2 REPLACEMENT OF COMPONENTS 79

A. 3 BARRIER MATERIALS 80

A. 3.1 CEMENTITIOUS COATING 80

A. 3. 2 AGGREGATE FILLED PAINT (FILLED PAINT) 81

A. 3. 3 GYPSUM IMPREGNATED JUTE FABRIC (GYPUSM JUTE) . . 81

A. 3. 4 CEMENT IMPREGNATED GLASS FABRIC (GYPSUM FIBERGLASS) 81

A. 3. 5 VINYL-COATED FABRIC 82

A. 3. 6 GYPSUM VENEER PLASTER 82

A. 3. 7 GYPSUM PLASTER WITH METAL LATH 82

A. 3. 8 GYPSUM WALLBOARD 83

ix
Page

A. 3. 9 PLYWOOD ON FLOORS 84

A. 3. 10 MELAMINE COATED HARDBOARD 84

APPENDIX B: PACKAGE PLANS USED IN PHASE I 85

B.l WASHINGTON, SERIES I 85

B.2 WASHINGTON, SERIES II 85

B.3 ATLANTA, SERIES I 86

B.4 ATLANTA, SERIES II 86

APPENDIX C: APPROXIMATE RANGES OVER WHICH COST MODEL ESTIMATES

ARE VALID 88

REFERENCES 94
LIST OF FIGURES

Figure Page

2.1 Sample Dwelling Unit Cost Data Form 20

3.1 Graphical Cost Estimating Procedure for a Hypothetical Wall Abatement Technique 36

LIST OF TABLES

Table Page

2.1 Distribution of Dwelling Units Deleaded in Washington, D.C., by Construction Type and Age of Unit 10

2.2 Distribution of Dwelling Units Deleaded in Atlanta,

Georgia, by Construction Type and Age of Unit 11

2.3 Experimental Methods for Lead-Based Paint Abatement Used in Phase I of EHEP 13

2.4 The Distribution of Dwelling Units Assigned to

Series I and Series II Package Plans in Washington,

D.C. 16

2.5 The Distribution of Dwelling Units Assigned to

Series I and Series II Package Plans in Atlanta,

Georgia 16

3.1 Cost Estimating Procedure for Abatement of LeadBased Paint on Walls by Use of Gypsum Veneer Plaster 40

4.1 Average Direct Cost Per Square Foot Figures for

Phase I Wall Abatement Techniques 46

4.2 Ranking of Wall Abatement Techniques by Average

Direct Cost 47

4.3 Estimates of the Coefficients of the Determinants

of Direct Cost Per Square Foot for Wall Abatement

Techniques 49

4.4 Average Direct Cost Figures for Phase I Door

Abatement Techniques 51

4.5 Ranking of Door Abatement Techniques by Average

Direct Cost 53

4.6 Estimates of the Coefficients of the Determinants

of Per Unit Direct Cost for Door Abatement Techniques 54

4.7 Average Direct Cost Figures for Phase I Door

Frame Abatement Techniques 57

xi
Ta bl

e

Page

4.8 Ranking of Door Frame Abatement Techniques by

Average Direct Cost 58

4.9 Estimates of the Coefficients of the Determinants

of Per Unit Direct Cost for Door Frame Abatement

Techniques 60

4.10 Average Direct Cost Figures for Phase I Window

and Window Frame Abatement Techniques 62

4.11 Ranking of Window and Window Frame Abatement

Techniques by Average Direct Cost 64

4.12 Estimates of the Coefficients of the Determinants

of Per Unit Direct Costs for Window and Window

Frame Abatement Techniques 65

4.13 Average Direct Cost Per Linear Foot Figures for

Phase I Trim Abatement Techniques 68

4.14 Ranking of Trim Abatement Techniques by Average

Direct Cost 69

4.15 Estimates of the Coefficients of the Determinants

of Direct Cost Per Linear Foot for Trim Abatement

Techniques 70

C.l Values of the Determinants of Direct Cost for Wall

Abatement Techniques 89

C.2 Values of the Determinants of Direct Cost for Door

Abatement Techniques 90

C.3 Values of the Determinants of Direct Cost for Door

Frame Abatement Techniques 91

C.4 Values of the Determinants of Direct Cost for

Window and Window Frame Abatement Techniques 92

C.5 Values of the Determinants of Direct Cost for

Miscellaneous Trim Abatement Techniques 93

Xll
SI CONVERSION UNITS

The conversion factors and units contained in this report are in

accordance with the International System of Units (abbreviated SI for

Systeme International d'Unites). The SI was defined and given official

status by the 11th General Conference on Weights and Measures which met

in Paris in October 1960. For assistance in converting U.S. customary

units to SI units, see ASTM E 380, ASTM Standard Metric Practice Guide,

available from the American Society for Testing and Materials, 1916 Race

Street, Philadelphia, PA. 19103. The conversion factors for the units

found in this Standard are as follows:

Length

1 in = 0.0254* meter

1 ft = 0.3048* meter

1 mil = 0.001* in

Area

1 in

2 = 6.4516* x 10" 4

meter

2

1 ft

2

= 0.0929 meter

2

Volume

1 in

3

= 1.639 x 10" 5meter

3

1 liter = 1.00* x 10" 3meter

3

Mass

_5

1 grain = 6.479 x 10 kilogram

1 ounce-mass (avoirdupois) = 2.835 x 10 kilogram

1 pound-mass (avoirdupois) = 0.4536 kilogram

Pressure or Stress (Force/Area)

2

1 inch of mercury (60°F) = 3377 newton/meter

2

1 pound-force/inch (psi) = 6894 newton/meter

'Exactly

X1X1
Energy

1 inch-pound-force (in-lbf) = 0.1130 joule

Plane Angle

1 degree (angle) = 1.745 x 10 radian

Power

1 watt = 1.00* x 10 erg/second

Temperature

°C = 5/9 (Temperature °F - 32)

*Exactly

xiv
1. INTRODUCTION

1.1 Background (The Experimental Hazard Elimination Program (EHEP))

Lead poisoning represents a serious problem to the health and wellbeing of the nation's children. The disease, as indicated by elevated

blood lead levels, has been estimated to affect approximately 600,000

children below the age of seven. There are a number of potential

environmental sources of lead, including leaded gasoline, food and

water, as well as lead-based paint.

Lead-based paint (LBP) poisoning is presumed to be precipitated by

the ingestion of LBP chips. The nature of LBP poisoning is such that

children, usually between the age of one and seven, are the primary

victims. Many children in this age bracket have a natural tendency to

place foreign objects into their mouths. Also they are usually unable

to distinguish a potentially dangerous substance from one that is not

dangerous. Therefore, LBP chips may be eaten without the child realizing that lead poisoning may result. And if illness should result, the

child may not associate the effect with the eating of LBP chips. The

disease is most acute among children who suffer from pica, or the

abnormal craving for unnatural food substances. The greatest potential

for LBP poisoning may therefore exist in dwelling units where young

children have access to LBP chips which have fallen to the floor or are

easily picked or dislodged from a painted surface.

LBP is found primarily in older housing, especially those units

constructed before 1950. Before the advent of modern coatings technology, LBP was considered to be the most durable paint available for

1 Judith F. Gilsinn, Estimates of the Nature and Extent of Lead

Paint Poisoning in the United States, National Bureau of Standards,

Technical Note 746, December 19/z, p. 104.
residential use. A recent survey involving a random sample of approximately 3,300 dwelling units in Pittsburgh, Pennsylvania, indicated that

approximately 1,900 dwelling units had a lead content (on at least one

wall) of 2.0 milligrams per square centimeter (mg/cm ) or more. This

survey also revealed that approximately 62% of all dwelling units constructed before 1940 and that slightly over 31% of all dwelling units

2 constructed between 1940 and 1960 had lead contents of 2.0 mg/cm or

more on at least one wall. It was also revealed in this survey that

lead-based paint was used in a significant number (approximately 13%) of

dwelling units 'constructed after 1960. The Pittsburgh survey provides

some measure of how widespread the use of lead-based paint was in housing in the Middle Atlantic geographical region. It can also give some

insight into what proportion of the nation's housing contains lead-based

paint.

A national estimate prepared in 1972 indicated that approximately

7,750,000 or about 27% of the 29,000,000 pre-1940 dwelling units were

3 deteriorating or dilapidated and also contained LBP. Data collected

during the Pittsburgh survey indicated that 32% of the pre 1940 dwelling units had peeling paint or poor substrate conditions which can be

used as a surrogate for deterioration or dilapidation. Thus the two

figures (of 27% for the initial estimate and 32% in the Pittsburgh

1 2 A lead content of 2.0 mg/cm is used in this illustration due to

potential measurement inaccuracies of the lead detection instruments at

lead levels below 2.0 mg/cm .

2 Based on computer analyses conducted by William Hall, Mathematician, Operations Research Section, Applied Mathematics Division, Institute for Basic Standards, National Bureau of Standards.

3 Judith F. Gil sinn, Estimates of the Nature and Extent nf I pad

Paint Poisoning in the United States, National Bureau of Standards, Techmeal Note /4b, December iy/2, p. 13b.
Survey) for the proportion of all pre 1940 dwelling units which represent lead paint hazards are roughly comparable.

The magnitude of the problem has stimulated a great deal of interest and concern from private individuals and public officials alike.

This increased interest resulted in the "Lead-Based Paint Poisoning

Prevention Act" (PL 91-695) enacted by Congress on January 13, 1971 and

amended (PL 93-151) on November 9, 1973, and established the need for

Federal participation.

Through the "Lead-Based Paint Poisoning Prevention Act," Congress

has delegated to the Department of Housing and Urban Development (HUD)

the leadership role in developing the technical information which is

required to determine the abatement procedures which will effectively

abate LBP hazards and which will promote economic efficiency in the

allocation of resources to eliminate high levels of LBP in housing. The

Experimental Hazard Elimination Program (EHEP) is intended to contribute

to the accomplishment of these goals in two ways. First, it permits the

technical evaluation of experimental LBP abatement techniques in field

deleading operations. Second, through the collection of data on direct

costs it provides a framework for estimating the costs of future LBP

hazard abatement operations.

The EHEP deleading operations involved the abatement of hazardous

levels of LBP in 110 housing units during Phase I. Thirty dwellings

were initially deleaded in Washington, D.C.; the remaining 80 were

deleaded in Atlanta, Georgia shortly thereafter. Information on the

technical and engineering aspects of the Washington and Atlanta portions

of Phase I is given in The Demonstration of Experimental Lead Paint
Hazard Abatement Methods in Washington, D.C. , and The Demonstration of

2 Experimental Lead Paint Hazard Abatement Methods in Atlanta, Georgia .

1 .2 Purpose

Under Title III of the "Lead-Based Paint Poisoning Prevention Act,"

HUD was directed by Congress to conduct a research program which would

facilitate the development of technologies by which the LBP hazard could

be eliminated. Implicit in Title III is an analysis of the associated

costs of LBP abatement.

The purpose of this report is to present an analysis of the directcosts of experimental abatement techniques based on an evaluation of

cost data collected in two cities, Washington and Atlanta, during Phase

I of EHEP. The analysis of this data will aid in the identification of

those hazard abatement techniques which promote economic efficiency at

the dwelling unit level. Cost estimating procedures based on the Phase

I EHEP data are proposed that (1) rank LBP abatement techniques with

regard to their relative costs, (2) identify those variables which have

greatest impact on direct costs, and (3) provide computational and

graphical procedures for estimating direct costs of deleading applicable

to future LBP hazard abatement operations.

1 .3 Scope and Approach

The focus of this study is on Phase I of HUD's Experimental Hazard

Elimination Program.

Thomas H. Boone, Harvey W. Berger, A. Philip Cramp, Herbert A. Jackson, The Demonstration of Experimental Lead Paint Hazard Abatement

lethods in Washington, D.C. , National Bureau of Standards, interagency

Report 75-761 , June 1975,

2 Thomas H. Boone, Harvey W. Berger, A. Philip Cramp, Herbert A. Jackson, The Demonstration of Experimental Lead Paint Hazard Aba tement

Methods in Atlanta, Georgia , National Bureau of Standards, interagency

Report 75-974, December 1975.
The emphasis of this study is on the analysis of direct cost data

from field deleading operations undertaken in Washington and Atlanta.

The analysis of the data is directed at the formulation of a cost model

which provides a methodology for the estimation of direct costs at the

dwelling unit level

.

The available cost data was analyzed by building component, i.e.,

walls, doors, door frames, windows and frames, and other miscellaneous

trim. The various abatement techniques utilized within a building

component were compared and contrasted to determine if some form of

ranking was possible. Once abatement techniques were grouped into categories with regard to their relative costs, the determinants of direct

cost were hypothesized and relevant functional relationships established. Suggestions for further research which will refine the procedures developed with the Phase I EHEP data are given in the remainder of

this report.

In its focus on cost estimation, this study does not attempt to

develop a methodology for the definition and quantification of benefits

to be derived from LBP hazard abatement. Nor does it attempt to estimate future costs or life-cycle costs resulting from maintenance or

repair necessitated by lack of long-term durability of an abatement

technique. The data collected from Phase I of EHEP did not allow the

identification and quantification of the sources and determinants of

variations in markup over direct costs. In the absence of information

on the potential benefits to be derived from abatement, expected future

•costs, and associated markups, no attempt was made to identify the

economically optimal abatement technique at either the dwelling unit

level or the national level. Similarly, incentives for large-scale

abatement programs such as cost-sharing and low-interest loans are not

treated.
2. DESCRIPTION OF PHASE I EHEP

2.1 Site Selection

The selection of candidate cities for field deleading operations

reflected both the desire for the collection of meaningful cost information and the constraints under which this portion of EHEP had to operate. Since the allocation of EHEP resources did not involve LBP abatement in privately owned dwellings, the availability of housing owned by

the Federal government or local housing authorities had to be considered

in the selection of a candidate city. Furthermore, in order to obtain a

cross section of housing types, in addition to HUD-owned properties,

some local housing units were required to be included. Thus the interests and willingness of local housing authorities to participate in

EHEP had to be assessed. Lead poisoning incidence data for cities were

then reviewed to see if the incidence of elevated blood lead levels was

high, since it was hypothesized that this would be a strong indication

that the number of dwelling units with acute lead levels was also sizable. Implicit in these considerations was that the city should have

housing representative of those types and ages of dwellings deemed

likely to contain hazardous levels of LBP.

2.1.1 The Selection of Washington, D.C.

A preliminary review of available data for cities indicated that

Washington had a relatively high incidence of children with elevated

blood lead levels. Furthermore, investigation of census tract data

showed that there exists within the city a varied stock of housing types

which are deemed likely to contain hazardous levels of LBP.

Early discussions with District officials laid the groundwork for a

cooperative agreement between HUD, the National Bureau of Standards
(NBS) and the National Capital Housing Authority (NCHA) . This agreement coupled with the proximity of HUD and NBS facilitated both the

implementation and control of this portion of Phase I. Interactions

between HUD, NBS, NCHA and the contract management firm, the Boeing

Aerospace Company, indicated that several modifications could be made in

Phase I which would significantly enhance overall program performance.

These modifications improved efficiency in screening, selection and

2 monitoring of dwelling units as well as in data collection.

2.1.2 The Selection of Atlanta, Georgia

Once the initial field operations were underway in Washington, the

selection of a second city with a larger number and variety of housing

units which could be tested was necessary to complete Phase I of EHEP.

Atlanta was a likely candidate because of its high incidence of

elevated blood lead levels. There was also a large stock of housing

owned by the local housing authority which was easily available for

abatement. In addition, Atlanta's census tract data indicated that it

had those housing types which are most likely to contain hazardous

levels of LBP. There was also a strong indication that the construction

and material types involved were representative of the Southeast as a

demographic region. Finally, the availability of approximately 600

dwelling units acquired by HUD through default on HUD insured mortgages

presented the opportunity to gather abatement costs on single-family

dwellings.

2.2 Dwelling Unit Selection

Implicit in the selection of dwelling units for abatement was the requirement of the overall program to collect meaningful cost information.

Thomas H. Boone, et al

.

, The Demonstration of Experimental Lead

Paint Hazard Abatement Methods in Washington, D.C. , p. 7.

2 Ibid. , p. 7.
In order to be able to retrieve the most usable information from the

experiment, it was necessary to select enough dwelling units so that

statistical testing would be possible. To do this efficiently, some

form of experimental design was required to distribute the appropriate

number of dwelling units according to some attribute or combination of

attributes, such as construction type, age of the dwelling, substrate

condition (i.e., the underlying material to which the paint film adheres), or occupancy status. The reliability of statistical comparisons is facilitated when constraints are placed on variables such as the

geographical distribution of the dwelling units and the maximum and

minimum surface which can be abated. If adequate control is not exercised in the form of experimental design and variable constraints, the

ability to estimate per unit direct costs is unnecessarily complicated.

In fact, if relevant constraints are removed, the potential sources of

variations increase rapidly and may confound the data so that the confidence with which statistical tests can be applied and considered

relevant is significantly reduced.

Once a pool of dwelling units had been selected from the overall

stock of housing, a team was sent to each dwelling to ascertain whether

or not the units contained hazardous levels of LBP. The team was equipped with a portable x-ray flourescence (XRF) lead detector with which

lead level readings were taken and recorded. The physical measurements

and other attributes of the units were also taken and recorded at that

time.

Any unit for which abatement was to take place had to satisfy a set

of three selection criteria, outlined below, as well as fit a housing

] In both portions of Phase I a housing sample selection plan was formulated. Problems in implementing these plans with available housing

however, resulted in departures from the experimental design set forth

in the housing sample selection plans.
sample selection plan. The three criteria set constraints on acceptable

lead content, on physical conditions, and on LBP locations and surface

dimensions.

Throughout Phase I of EHEP, a hazardous level of LBP was said to

exist if a dwelling unit had painted surfaces which revealed a lead

content of 2.0 milligrams per square centimeter or more. Second, a

hazardous level of LBP was said to exist if the paint was cracked,

scaling, peeling or chipping, or there was LBP painted trim within four

2 feet of the floor. The third criterion was that the unit had to have

surfaces requiring abatement that satisfied at least one of the following constraints: 500 square feet of wall area; four windows; four

doors; or 50 linear feet of miscellaneous trim. Finally, the unit had

to fit the housing sample selection plan.

2.2.1 Dwelling Unit Selection in Washington, D.C.

All dwelling units which had hazardous levels of LBP abated in

Washington were selected from the National Capital Housing Authority

(NCHA) housing stock. This stock comprises about 12,000 units the

majority of which are in large apartment complexes. Most of the 50 NCHA

apartment complexes are relatively new, only 10 having been built before

1945. There are also between 300 and 400 single-family units within the

jurisdiction of the NCHA, the majority of which were constructed before

1940.

During the course of the survey only single-family attached and

multi-family low rise units were found to meet the criteria for lead

Standards as to what is the minimum level of lead content above

which it is considered hazardous may vary from city to city. The definition cited above was selected due to the potential inaccuracies of £he

instruments used in this phase of EHEP at lead levels below 2.0 mg/cm .

2 Painted trim within five feet of the floor constituted a hazardous

level of LBP in the Washington portion of Phase I.
content, physical conditions, locations, and surface dimensions. Of the

30 dwelling units selected for LBP abatement in Washington, 13 were

single-family attached, and 17 were multi-family low rise. The multifamily low rise units were distributed between two apartment complexes

with 12 and 5 dwelling units each; the single-family attached units were

spread throughout the city. All but 3 of the 30 units were occupied.

In addition to the high occupancy rate, all units were found to be

structurally sound. Thus potential variations in cost due to occupancy

status or substrate condition were not identifiable.

The distribution of dwelling units deleaded in Washington is given

in Table 2.1 .

TABLE 2.1

DISTRIBUTION OF DWELLING UNITS DELEADED IN WASHINGTON, D.C.

BY CONSTRUCTION TYPE AND AGE OF UNIT

Construction

Type

Age of Unit

Pre 1920 1920-1940 1940-1950 Total

Single-Family

Attached 5 7 1 13

Multi-Family

Low Rise 17 17

TOTAL 5 24 1 30

2.2.2 Dwelling Unit Selection in Atlanta, Georgia

The stock of housing available for LBP abatement under Phase I of

EHEP in Atlanta, Georgia, consisted of approximately 10,800 units owned

by the local housing authority and about 600 units which HUD had acquired through mortgage default. The HUD acquired properties differ

10
from those owned by the local housing authority in that they are primarily single-family detached dwellings.

Eighty units from the local housing authority's stock were screened, of which 48 were found to satisfy the three dwelling unit selection

criteria. All 48 of these units were occupied, and they were distributed between three apartment complexes. From the 600 HUD-owned properties, 32 units were selected, all of which were unoccupied.

As in Washington, the condition of the substrate of the dwelling

units selected for deleading was relatively good, so that estimates of

repair costs were not usually available.

The distribution of dwelling units deleaded in Atlanta is given in

Table 2.2.

TABLE 2.2

DISTRIBUTION OF DWELLING UNITS DELEADED IN ATLANTA, GEORGIA

BY CONSTRUCTION TYPE AND AGE OF UNIT

Construction

Type

Age of Unit •

Pre 1920 1920-1940 1940-1950 Total

Single-Family

Detached 4 23 5 32

Multi -Family

Low Rise 40 8 48

TOTAL 4 63 13 80

2.3 Abatement Technique Selection

The experimental abatement techniques tested in Phase I of ehep

were selected on the basis of recommendations set forth after an extensive laboratory testing program conducted at the National Bureau of

11
Standards. Detailed descriptions of the testing procedures, the performance criteria, and the experimental abatement techniques tested are

available.

The effective abatement of LBP may be accomplished through three

basic methods: (1) paint removal, (2) component replacement, and (3)

barrier materials. The method actually used will depend upon the building component to be deleaded. Building components are conveniently

grouped into two types: (1) planar surfaces (walls, ceilings, porch

decks), and (2) trim (doors, door frames, windows and frames, porch

railings and other miscellaneous trim surfaces). For the purposes of

this study, doors are separated from door frames as a building component

since doors may be physically removed from the dwelling and treated

independently of their frames.

A breakdown of the three basic abatement methods into specific

techniques exhibiting the building components applicable to that technique is given in Table 2.3. The abatement techniques used in Phase I

of EHEP are described briefly in Appendix A. Detailed requirements for

the preparation, installation and finishing work as well as construction

specifications of the individual abatement techniques may be found in

2 the two reports by Boone et al

.

Eight of the sixteen LBP abatement methods demonstrated in Atlanta

were used in the Washington portion of Phase I of EHEP. This repetition

should be emphasized in that it facilitates the identification and

David Waksman, John B. Ferguson, McClure Godette, and Thomas Reichard,

Potential Systems for Lead Hazard Elimination: Evaluations and Recommendations for Use , National Bureau of Standards, Technical Note 808, December

1973.

2 The Demonstration of Experimental Lead Paint Hazard Abatement

Methods in Washington, D.C. , pp. 71-95, and The Demonstration of Experimental Lead Paint Hazard AFatement Methods in Atlanta, Georgia , pp.

78-1 I I.

12
TABLE 2.3

EXPERIMENTAL METHODS FOR LEAD-BASED PAINT

ABATEMENT USED IN PHASE I OF EHEP

METHOD TECHNIQUE APPLICABLE BUILDING COMPONENT

PAINT REMOVAL SOLVENT STRIPPING ALL TRIM COMPONENTS

HAND SCRAPING ALL TRIM COMPONENTS

ELECTRIC HEAT GUN ALL TRIM COMPONENTS

INFRA-RED DEVICE ALL TRIM COMPONENTS

PROPANE TORCH EXTERIOR SURFACES ONLY

DIP TANK DOORS ONLY

COMPONENT

REPLACEMENT ALL TRIM COMPONENTS

BARRIER

MATERIALS CEMENTITIOUS

COATING WALLS & BASEBOARDS

FILLED PAINT WALLS

GYSUM JUTE WALLS

GYPSUM FIBERGLASS WALLS

VINYL-COATED

FABRIC WALLS

VENEER PLASTER WALLS

PLASTER WITH LATH WALLS

GYPSUM WALLBOARD WALLS

PLYWOOD FLOORS

MELAMINE PANELING WALLS

13
determination of variations in costs or quality of workmanship resulting

from regional differences, different housing conditions and types, the

availability of local labor, the prevailing labor rates, and the types

of contractors performing the abatement.

2.4 Assignment of Abatement Techniques to the Stock of Dwelling Units

The collection of meaningful cost information from the dwelling

units selected for LBP abatement hinges on a methodology through which

factors contributing to the variation in direct cost can be adequately

determined and measured. Recognition of this problem as well as other

constraints, such as contractor unfamiliarity with some abatement techniques, prompted the formulation of a set of package plans. These package plans were designed to tailor the abatement techniques to meet the

specific requirements of the individual dwelling unit. The use of the

package plans also provided some assurance that each abatement technique

would be used at least once.

The combinations of abatement techniques used in the package plans

was a synthesis of laboratory test results and engineering judgment.

Though the rationale behind the formulation of the package plans was

sound, it did not guarantee that abatement techniques would be assigned

in such a way that the cost data collected could be rigorously analyzed.

The package plans implemented during Phase I were of two basic

types, reflecting the need for different methods for planar surfaces and

trim. Due to their composition and size, planar surfaces such as walls

and ceilings, generally require some form of barrier material. Scraping

and sanding is an alternative, albeit one which can produce sizable

quantities of leaded dust. Wall surfaces in bathrooms and kitchens (wet

walls) present additional problems with regard to adhesion since in

these areas moisture may cause separation of the barrier material from

14
the wall. This moisture may also accelerate the aging process so much

so that the barrier material rapidly becomes ineffective. The abatement

requirements for trim components such as doors or windows differ from

those of planar surfaces in that the former components are usually

designed to be operable by the occupant (e.g., adjusting ventilation by

opening or closing a window). Thus the application of barrier materials

to some trim components would generally not be acceptable since it would

severely limit the usefulness of these components. For trim components

there is also the question of taste and overall finished appearance.

Hence LBP abatement for trim components may be more easily accomplished

through the use of a paint removal or component replacement method.

Once special conditions such as unsound substrate, inoperable doors

or windows, or deterioration of other trim had been noted and assessed,

the dwelling units were assigned to the various package plans through

engineering judgment.

The distributions of dwelling units deleaded in Series I (planar

surfaces) and Series II (trim) package plans in Washington and Atlanta

are given in Tables 2.4 and 2.5 respectively. It should be noted that

Series I and Series II package plans are independent of each other; that

is, the trim deleaded in package plan I A may or may not use the same

set of abatement techniques as the trim deleaded in package plan II A.

The abatement techniques assigned to the Series I and Series II package

plans for each city are given in Appendix B.

2.5 Format and Methodology for Cost Data Collection

Upon the completion of the assignment of the abatement techniques

to the stock of dwelling units, competitive bids were solicited from

local contractors. Explicit in these bids were requirements for the

reporting of all direct costs for labor and materials. It should be

noted that direct cost figures differ from bid price figures in that

15
TABLE 2.4

THE DISTRIBUTION OF DWELLING UNITS ASSIGNED TO SERIES I AND SERIES II PACKAGE PLANS IN WASHINGTON, D.C.

Package Plan

Series A B C D E F G Total

I 2 2 3 3 5 15

II 4 3 4 1 2 1 15

30

The abatement techniques used in Series I and Series II package plans

in Washington are given in Appendix B.l and B.2.

TABLE 2.5

THE DISTRIBUTION OF DWELLING UNITS ASSIGNED TO

SERIES I AND SERIES II PACKAGE PLANS IN ATLANTA, GEORGIA

Package Plan

Series A B C D E F G H Total

I 9 8 8 4 5 4 2 40

II 3 3 10 2 6 10 6 40

80

The abatement techniques used in Series I and Series II package plans

in Atlanta are given in Appendix B.3 and B.4.

16
they represent the basic costs to the abatement contractor of labor and

materials, and hence exclude any markup for such things as employee

fringe benefits, overhead and profit. Phase I data were not collected

for estimating all project costs; rather, they were collected to provide

more basic information for estimating the quantities and types of labor

and materials which are required to perform a relatively unfamiliar

construction process.

The direct cost, DC, of an abatement technique may be expressed by

the following equation

DC - LC + MC 2.1

where

LC = direct labor cost, and

MC = direct material /equipment cost.

Labor costs for each abatement technique were further broken down

by component labor skills (e.g., laborer, carpenter and painter). To

compute the direct labor cost for a particular skill, it is necessary to

have data giving the number of manhours expended to perform the abatement process and the wage rate. The direct labor cost for that skill is

then given by the product of the manhours expended and the wage rate.

To derive the direct labor cost for a particular abatement technique,

the labor costs for the individual skills are summed.

The following equation expresses this concept mathematically

q LC = E M, W. 2.2

k=l

K K where

M. = the number of manhours expended by the kth skill type,

W, = the wage rate of the kth skill type, and

q = the number of distinct skills.

17
The computation of the direct material/equipment cost for each

abatement technique is analogous. Each material /equipment type associated with a particular abatement technique is identified. The unit

price of the material and quantity consumed are recorded; direct material cost for that material type is calculated by taking their product.

To arrive at direct material /equipment cost those material /equipment

types required for the abatement technique under consideration are

identified; individual material costs are then summed.

This concept may be expressed mathematically by the following equation

P MC = E U.Q. 2.3

k=l

K K where

U, = the unit price of the kth material /equipment type,

Q. = the quantity of the kth material /equipment type consumed, and

p

= the number of distinct material /equipment types.

The comparison of direct costs is facilitated by the introduction

of an average cost measure, which is a function of the total number of

units (square feet, item, linear feet) deleaded. This allows cost data

to be presented and analyzed on a per unit basis. The resultant figure

is denoted per unit direct cost, PDC. As with direct cost, per unit

direct cost may be expressed as

PDC = PLC + PMC 2.4

where

PLC = per unit labor cost, and

PMC = per unit material /equipment cost.

For purposes of this study, per unit direct cost figures are computed at

the dwelling unit level. Another measure which may also be considered

is the contract package level. This differs from the dwelling unit

18
level in that a contract package may contain more than one dwelling

unit. In this study the contract package level was not used, since it

provides less information on variations in wage rates, materials/

equipment costs and the productivity of labor. Contract package size

was useful however, as a variable in this study since wide variations in

the number of dwelling units deleaded by different contractors were

experienced in Phase I of EHEP.

The collection of direct cost data outlined above was accomplished

through the use of the Dwelling Unit Cost Data Form, a sample of which

is shown in Figure 2.1. The form is divided into several parts, each

representing a different abatement operation. This form improved the

efficiency with which data on each abatement technique could be collected on the preparation, installation and finishing operations of the

abatement process. As such it aided in the identification of those

portions of the abatement process which were or were not major sources

of variations in direct cost figures. Although the Dwelling Unit Cost

Data Form did prove satisfactory for the Phase I deleading operations,

it has a serious limitation in that whenever extensive abatement work

was required in a dwelling unit, it was difficult to separate all of the

abatement techniques in a package plan into their respective labor and

material/equipment components.

As mentioned earlier, abatement contractors were required to report

direct cost figures to the contract management firm. The method of

recording cost figures from abatement contractors however differed

between Washington and Atlanta. This resulted from a desire to improve

both the efficiency and accuracy with which cost figures were reported.

In Washington, cost data was collected after all abatement work was

completed. Unfortunately, the length of time between the start and

19
CONTRACT NUMBER: ADDRESS:

Material /Equipment

Sq. Ft Lin. Ft

Labor

Operation

(Series II Package Plan) Type Quant. ManHours Wage

Rate

A. Paint Removal or Replacement:

Doors Door Frames Windows and Frames Other Misc. Trim

Exterior Surfaces

B. Surface Repair:

Doors, Windows and Trim

Exterior Surfaces

C. Covering:

D. Painting:

Doors Door Frames Windows and Frames Other Misc. Trim

Exterior Surfaces

E. Clean up:

Door, Windows and Trim

Exterior Surfaces

F. Waste Disposal

:

Door, Windows, and Trim

Exterior Surfaces

G. Other:

Figure 2.1 SAMPLE DWELLING UNIT COST DATA FORM.

20
finish of the contract was long enough so that the accuracy with which

cost figures were reported may have suffered, especially if adequate

records were not kept during the abatement work. Furthermore, all

abatement work in Washington was done by the same contractor so that

less variations in wage rates, materials/equipment costs and productivity were experienced.

The major changes in the methodology by which cost data were collected in Atlanta involved the reduction of the size of the contract

packages so that more contractors were performing abatement work and the

added requirement that cost data figures be reported each week. With a

variety of contractors it became possible to measure the effects which

variations in wage rates and productivity have on direct costs. The

collection of cost figures each week strongly encouraged good record

keeping and hence improved the reliability of the figures recorded.

21
3. THEORETICAL ANALYSIS OF BUILDING COMPONENT COST DATA

The building component cost data collected in Phase I of EHEP was

analyzed by using a series of statistical tests. Statistical analysis

is needed because the data collected from Phase I deleading operations

have some degree of uncertainty associated with them. The sources of

this uncertainty are basically twofold. First, the data are incomplete

in that they contain cost information on only a small sample of what

may be denoted as the population of presently available LBP abatement

methods. Second, even for the abatement methods tested, the data are

based on only a small sample of units, not enough to capture all of the

potential sources of variation due to the effects of changes in wage

rate, the efficiency of labor, or the size of the abatement contract.

A statistical approach to the data analysis provides a methodology

which identifies and quantifies differences which may exist in direct

cost at the dwelling unit level. In addition, the use of statistical

procedures permits probabilistic levels of significance to be attached

to any conclusion regarding differences in direct costs. Furthermore,

a statistical approach facilitates the formulation of a model capable of

predicting direct costs for abatement techniques at the dwelling unit

level

.

The level of confidence which can be attached to any conclusion is

dependent upon several factors. First, the underlying assumptions for

any statistical procedure must be known and must be relevant to the data

under consideration. Second, the relative importance of rejecting a

hypothesis when it is true or accepting it when it is false must also

be assessed. Finally, implicit in all of these considerations is the

The probability of rejecting the formulated (null) hypothesis when

it is true is denoted a type I error; the probability of accepting the

alternative hypothesis when it is false is denoted a type II error.

22
trade-off between the size of the sample and the power of the test.

These considerations together with output requirements determined this

project's statistical approach as detailed in sections 3.1 through 3.5.

The reader who is interested primarily in the results of the analysis

may proceed directly to chapter 4.

3.1 Statistical Techniques Utilized

To facilitate the analysis of the Phase I EHEP cost data, the

statistical procedures of oneway analysis of variance and multiple

regression were used. Both were selected because the type and nature of

the data collected indicated that rather sophisticated methods were

needed. Furthermore, they permit the data to be reduced to a form from

which a prediction mechanism can be constructed. The application of

these statistical procedures to the cost data was accomplished through

the use of the NBS computer package OMNITAB II. OMNITAB II was selected because of its availability and its highly reliable statistical programs. Also, its numerical and graphical output provide an effective

3 way of testing if any of the underlying assumptions have been violated.

The initial testing of the Phase I EHEP cost data involved the

analysis of variance for a oneway classification. As a statistical

The probability of accepting the alternative hypothesis when it is

true is denoted the power of the test. Other things being equal, the

larger the sample, the greater is the power of the test.

2 David Hogben, Sally T. Peavy, Ruth N. Varner, OMNITAB II User's

Reference Manual , National Bureau of Standards, Technical Note 552,

October 1971

.

3 If the power of a test is relatively insensitive to the relaxation of one or more of its underlying assumptions, it is referred to as

a robust test. In the absence of robustness some means of testing for

the violation of the underlying assumptions is required.

The analysis of variance used here is referred to as oneway since

the data being analyzed are subject to only one dimension of classification, the abatement technique.

23
procedure, the oneway analysis of variance permits the testing of the

null hypothesis, whether observed differences among more than two sample

means can be attributed to chance, versus the alternative hypothesis,

that the observed differences are indicative of actual differences among

the means of the corresponding populations. That is, it provides a way

to test whether, for a particular building component, the observed

differences in direct costs for each abatement technique are attributable to chance versus the hypothesis that they indicate that real

differences in direct cost do exist between the different abatement

techniques. On the surface this may seem a rather simplistic statement

since the chance of having two or more abatement techniques with identical direct costs is very unlikely. Because of uncertainty, however,

finding a difference does not necessarily indicate that one is significantly more or less expensive than the other. What is of central importance here is that an analysis of variance approach permits the statement to be made with a given level of confidence that there does or does

not exist, for a given building component, a significant difference in

direct costs for different abatement techniques.

If after application of the analysis of variance the null hypothesis is rejected, it must be assumed that significant differences do

exist in the direct costs for different abatement techniques. Thus it

may be possible to rank abatement techniques with respect to their

An introduction to the analysis of variance is given in K.A.

Brownlee, Statistical Theory and Methodology in Science and Engineering , John Wiley and Sons, Inc., 1960. For a more mathematical treatment see

H. Scheffe, The Analysis of Variance , John Wiley and Sons, Inc., 1959.

A confidence level of 95% does not mean that the null hypothesis is

95% true; it is either true or false. It implies that if the null hypothesis were true and the experiment were repeated over and over under identi

cal circumstances 95 out of every 100 times the null hypothesis would be

accepted.

24
relative costs. Implicit in this ranking is a predetermined level of

confidence which is used to define the appropriate categories in which

the abatement techniques are grouped.

The division of the data into categories within which it is reasonable to assume equal average direct costs then permits further analysis

2 across abatement techniques of the structure and determinants of direct

cost through the use of multiple regression. Multiple regression may be

defined as a statistical procedure for investigating and quantifying the

relationship between the dependent or response variable and two or more

3 independent variables.

In the course of the analysis of the Phase I cost data, three measures of direct cost were used as response variables: (1) the per unit

direct cost, (2) the per unit labor cost, and (3) the per unit material/equipment cost. Independent variables (those which determine per

unit direct cost) included the average wage rate, the quantity of surface deleaded, the productivity of labor, and the contract package size. 4

Throughout the analysis, the structure of the model was assumed to be of

the linear form

m

PDC = 3 + Z 3-X. + e, 3.1

o j=l *J J

For purposes of ranking, a confidence level of 95% was used.

2 The term structure is used to denote the basic relationship bet- ween the variables and how they affect direct cost; determinants refer

to specific variables which affect direct costs.

3 For a general discussion of multiple regression see K.A. Brownlee,

Statistical Theory and Methodology in Science and Engineering , John Wiley

and Sons, Inc. , 1960. For an indepth analysis see N.R. Draper and H. Smith,

Applied Regression Analysis , John Wiley and Sons, Inc., 1966.

4

Precise definitions of these variables will be given in section 3.2.

25
where PDC = per unit direct cost, the response variable,

g = the intercept term,

g. = the coefficients of the independent variables,

X. = the independent variables, and

e = the error term.

The methodology through which the underlying structure and determinants of per unit direct cost were analyzed involves a four stage

iterative process of (1) selecting a model, (2) estimating the coefficients, $., (3) testing the validity of the underlying assumptions, and

J (4) testing the adequacy of the model. Once estimated, the finalized

model can be used as a mechanism with which to predict direct costs for

abatement techniques at the dwelling unit level. Under relatively mild

assumptions, the regression curves can be plotted, providing a framework

for a graphical cost estimating procedure.

3.2 Comparison and Ranking

Initially the data were analyzed through the use of the oneway

analysis of variance. The null hypothesis that the per unit direct

costs for all abatement techniques within a building component were

equal was tested against the alternative hypothesis that per unit direct

costs were not all equal. The acceptance or rejection of the null

hypothesis was based on whether or not the resulting F ratio was greater

2 than the theoretical F ratio for the predetermined confidence level.

The intercept term is included since the assumption that the response

is zero when all independent variables are zero is a rather strong and

usually unjustified assumption.

2 The acceptance region for the null hypothesis is given by the 95%

k point of the F distribution with k-1 and z n. - k degrees of freedom,

i = l

] where k equals the number of abatement techniques and n^ equals the number

of experimental observations for the ith technique. The F ratio resulting

from the observed data is computed by dividing the among-techniques mean

square by the Within-techniques mean square.

26
For the purposes of the experimental LBP abatement program, the set of

abatement techniques may be considered to be fixed. This has as a

consequence that the type of analysis of variance model under consideration is a fixed effects model.

The data base was prepared for analysis by first separating it into

2 its respective building components. The data were then subdivided

within each building component into abatement techniques. To provide an

adequate point of reference from which abatement techniques could be

compared, they were tabulated with respect to their dwelling units.

Once the data base was arranged in this way, it was possible to read the

relevant information directly from the Dwelling Unit Cost Data Form.

However, before the actual analysis could begin, it was necessary to

reduce all cost data to a per unit basis. To accomplish this, the figures for labor costs, material/equipment costs, the quantity of surface

deleaded, and the total manhours expended were calculated. At this time

several other variables which were involved in the analysis were computed. These were the average wage rate, the productivity of labor and

the contract package size. The average wage rate reflects the average

wage which would be paid per manhour for a given abatement technique

over the complete abatement process. It may be expressed mathematically

as

n AWR = Z P.M. , 3.2

1-1 " '

Hhis assumption has some interesting theoretical implications, in

that it permits, generally speaking, more definitive statements to be

made with the same set of data than other analysis-of-variance models.

Future studies may indicate that additional abatement techniques are feasible in which case the assumption of a fixed effects model would be

a bit stronger than required. In. the absence of any such indication,

however, it appears that the assumption of a fixed effects model is justified.

2 It should be recalled that building components denote ^walls, doors,

door frames, windows and frames, and other miscellaneous trim.

27
where AWR = average wage rate,

P. = the proportion of the total manhours expended by the ith

labor type,

W- = the wage of the ith labor type,

and

n

E P. = 1 . 3.3

1=1 '

1 The average productivity of labor is the number of units which can be

processed in one manhour, that is the total number of units processed

divided by the total manhours. The contract package size is the total

number of dwelling units being deleaded by the contractor who is performing the abatement work in the dwelling unit under consideration.

The analysis of variance model was applied to data for each building component on per unit direct cost, per unit labor cost, per unit

material /equipment cost, and the productivity of labor. The results of

tests on direct cost for each building component are given in chapter 4.

2 To insure that the underlying assumptions were not violated, two

3 backup tests were used. First, the Cochran C test was used to test the

validity of the assumption that the variance of the abatement techniques

was the same. Second, should the assumption of an underlying normal

4 distribution be unjustified, the Kruskal-Wallis H test was used. The

Kruskal-Wall is H test was selected because it is a non-parametric test

which uses the ranks of the experimental observations and avoids any

assumption about the underlying distribution.

Units denote square feet, linear feet, the number of doors, door

frames, or windows and frames.

o The sample observations assumed to be independent normally distributed random variables with equal variance.

3 W.J. Dixon and F.J. Massey, Introduction to Statistical Analysis , McGraw-Hill Book Company, 1957, p. 180.

K.A. Brownlee, Statistical Theory and Methodology in Science and

Engineering , pp. 194-196.

28
If the oneway analysis of variance results indicated that the

difference between abatement techniques for a particular building component was not attributable to chance, a pairwise multiple comparison of

means was performed. The purpose of this test was to group the abatement techniques into categories such that the means of the abatement

techniques within a category were not significantly different at the 95%

confidence level, but that -the means in different categories were

significantly different at this level. The grouping into categories was

accomplished through the application of the Scheffe method. This

method was selected since it did not require an equal number of obser2 vations for each abatement technique.

The results of the Scheffe method permitted abatement techniques to

be ranked by their direct costs into categories from least expensive to

most expensive. If a oneway analysis of variance were applied to the

abatement techniques within a given category, the null hypothesis (i.e.,

3 equality of means for direct costs) is expected to be accepted. This

is due to the way in which the test was formulated.

3.3 Establishment of Functional Relationships

The categories established through the sequence of the analysis of

variance and the Scheffe method for pairwise multiple comparison of

K.A. Brownlee, Statistical Theory and Methodology in Science and

Engineering , pp. 252-254.

2 In the event that an equal number of observations for each technique does occur, the Newman-Keuls-Hartley method may be used. Details

of this method are given in G.W. Snedecor, Statistical Methods , Fifth

Edition, Iowa State University Press, 1956.

3 If the 95% confidence interval constructed with the Scheffe method

was wide enough, it is conceivab-le that when an analysis of variance is

performed the resulting F ratio would exceed the 95% point of the appropriate F distribution. However, this problem did not arise with any of

the Phase I data.

29
means open the way for the analysis of the underlying structure and

determinants of direct cost. The similarity of the structure of

direct costs for abatement techniques within a category lends itself to

across technique comparisons of variables and the establishment of

functional relationships through the use of multiple regression. As

mentioned earlier, the form of the multiple regression model was taken

to be linear.

To begin the four stage iterative process for the regression model

development, four variables were selected for intial testing: (1) the

quantity of surface deleaded, (2) the average wage rate, (3) the productivity of labor, and (4) the size of the contract. The response

variable for this portion of the model development was per unit direct

cost. Attempts were also made for each building component and category

to develop separate regression models for both per unit labor and material/equipment costs.

The construction of the regression model was facilitated by the use

of two statistical procedures, the sequential F test and the partial F

test. These tests were used to assess the relative importance of variables added to the structure of the model. The sequential F test is

used to test whether the model is made significantly better by the

addition of a particular variable whereas the partial F test is used to

test whether the whole model is significantly better than a reduced

model which includes this particular variable. Taken in conjunction,

When the form of the model is given by m

Y

= S

o +

f,

s

J X

j + *•

the sequential F test will tell if

t

o

j = 1 J ;i Y = 3. + E 3..X.. + e

is significantly better than

(Continued on Next Page)

30
they permit the deletion of variables which have negligible impact on

direct costs and provide a well defined stopping procedure to insure

that the model does not become unwieldly.

New variables continue to be added to the model until the values of

the partial and sequential F tests are no longer significant. The

coefficients of the model variables, 3., are then estimated through the

use of the method of least squares. The method of least squares was

chosen because the estimates it provides possess several highly desirable statistical attributes.

(1 continued from preceding page)

t-1

Y = s + E B.X. + e,

'' j=l '

! whereas the partial F test will tell if m

Y = 3_ + E 6.-X.. + e

is significantly better than

j=1 j j

t-1

Y = 3 + 1 3.X. + e. M

where m > t > 1

.

J J

The method of least squares provides a methodology where by the sum of the squared difference of the observed and predicted values of the n experiemental observations

n

,2 E (Y. - Y.) is minimized,

i=l

1 n where Y. = the experimental value of the observations, and

Y

1

. = the predicted value of the observation.

2 Least squares estimates are both linear combinations of the experimental observations, Y., and minimum variance unbiased estimators of the

3.. Furthermore, they1 exhibit normality whenever the Y.. are normally distributed.

31
The finalized model is assessed for adequacy through the use of a

1 2 graphical technique which plots the standardized residuals under the

assumption that they are independent normally distributed random variables. This test for adequacy is of great importance since, if the

standardized residuals are not independent normally distributed random

variables, it is not possible to perform either the sequential or

partial F test as an aid in determining when to stop adding variables.

4 A second test used involved correlation techniques. These techniques describe the linear, statistical, relationship between two normally distributed random variables. As such they provide a tool for

identifying potential sources of multicol linearity, a situation that

arises when one or more of the explanatory variables provide essentially

the same information. Multicol linearity is undesirable since it reduces

the precision of the estimates of the p.. The correlation coefficient

J takes on values between -1 and +1. Values close to +1 or -1 indicate a

5 high degree of positive or negative correlation respectively. A value

of indicates that the two variables are uncorrelated. When variables

were found to be highly correlated at the 95% conficence level they were

either transformed or deleted from the analysis to prevent the problems

for estimation caused by multicollinearity.

This graphical technique is sometimes referred to as a probability plot.

The standardized residuals are equal to the residuals (the difference between the observed and predicted values).divided by .the. standard

deviation of the predicted values (a measure of dispersion between the

observed and predicted values).

3 This as well as other consequences are outlined in N.R. Draper

and H. Smith, Applied Regression Analysis , p. 59.

David Hogben, Sally T. Peavy, and Ruth N. Varner, OMNITAB II User's

Reference Manual , pp. 155-162.

5 Positive correlation means that the values of the two variables move

in the same direction; negative correlation means that they move in opposite directions.

32
To gain some measure of what portion of all variations in direct

costs are explained by the finalized model, it was necessary to compute

2 the coefficient of multiple determination, R . The coefficient of

multiple determination takes on values between and 1, where the

2 closer R is to 1 the more complete the model is at explaining the

variations in direct costs. Since the number of observations for the

different categories was subject to a great deal of variability, it was

2 necessary to adjust R to reflect both the number of observations and

the number of variables used to predict per unit direct cost. This

2 _2 _2

adjusted value of R is denoted R . The observed values of R for the

Phase I data ranged from 0.43 to 0.94. It should be noted that some of

these low values resulted since separating data into distinct groups may

be a formidable task when problems of interaction occur. The introduction of a dummy variable may relieve this situation somewhat.

Examples of uses of a dummy variable to improve the predictive capabilities of the model are dividing wages into union and nonunion pay

scales and indicating if a dwelling unit is occupied or not. The two

dummy variables just mentioned would not be effective, however, if union

scale labor were used only in occupied dwellings and nonunion scale

labor only in unoccupied dwellings. This problem did occur in Phase I _2

and as a result relatively low values of R on some building components

are included. To improve the predictive capability of the model for

these components would require additional data.

3.4 Graphical Cost Estimating Procedure

Ideally a cost estimating procedure should be both reliable and

easy to use. The multiple regression model described earlier has

several attributes which make it attractive, especially its ability to

Dummy variables take on a value of either or 1 depending on whether some specific statement is true or false.

33
predict direct costs. The finalized form of the regression model was

found to be

PDC = B Q + p

1 X1 + 3 2 X2 + 3 3 X3 + 3^4 + e, 3.4

where

X, = the quantity of surface deleaded,

X

?

= the average wage rate,

Xo = the productivity of labor,

X- = the contract package size, and

e = the error term.

When the estimated values of the 3-'s (b.'s) are incorported in the

model, it may be written as

PDC = b + b,X, + b X„ + b Q X_ + b.X.. 3.5

o 11 2 2 3 3 4 4

This basic form may be further simplified with several reasonable

assumptions. Under the assumption that productivity and contract package size are held constant, it becomes possible to plot per unit direct

cost versus the quantity of surface deleaded. It should be noted that

the simplified form of equation 3.5 is given by

PDC = b^ + b

] X

] + b2 X

2

, 3.6

where b' now reflects b , the constant values for productivity, the

2 contract package size, and the estimated values b~ and b..

The assumption that productivity is constant implies that productivity is independent of the other variables, that is E(XJX, ,X„,X ) = E(Xo) = c. If this is deemed too strong an assumption, it shoula

be noted that rejecting it would require computing the expected value

of X

3 for each set of given values of X-j ,X 2 and X^. It is doubtful that

such an endeavor, which would be affected by uncertainty, would produce

any better results than that of assuming productivity constant.

2 The use of the b. notation reflects that the equation in question

contains the estimated values of the 3-'s.

vJ

34
For purposes of illustration, consider a certain category of wall

abatement techniques. Cost data was collected for wall areas ranging

from 300 square feet to 900 square feet. At the same time the respective average wage rate, AWR, varied from $3.75 to $8.75 per hour. Using

this information, it is possible to construct a family of curves associated with various average wage rates (see Figure 3.1). So that each

curve may be easily distinguished, the respective per unit direct costs

are denoted PDC„ , where X

? denotes the average wage rate. Individual

values of X, on the curve PDC V are denoted PDC Y Y

. Taking as initial

I An Ap , A-i values for X

? and X, the average wage rate of $3.75 per hour and the

minimum value of wall area deleaded of 300 square feet, the equation for

per unit direct cost becomes

PDC. 7f- Qnn = b ' + b-,300 + b 9 -3.75. 3.7 3./b,3UU O ! 2 Holding X

? constant at $3.75 per hour and increasing X, until it equals

the maximum value of wall area deleaded (i.e., 900 square feet), the

equation for per unit direct cost then becomes

PDC, 7C nnn = b' + b,900 + b -3.75. 3.8

3.75,900 o 1 2 Since the finalized regression model was linear in form, it is possible

to connect the two points, PDC~ 7t- -, 0Q and PDC^ 7I- qnf., with a straight

line. The resultant curve is denoted PDC, -,,-. 3.75

In a similar fashion the curves PDC, QQ , PDC.

25

and so on in

increments of 0.25 to PDC

ft 75 may be constructed. Furthermore the PDC„

curves are parallel with slope equal to b, so that the vertical difference between any two curves is constant. This has as the consequence, since the family of curves is infinite, that any per unit cost

curve can be approximated arbitrarily closely. However the improvement

Since the vertical distance between any two curves PDCxA and PDCy^

is a constant d, any curve in between, PDCx?, may be determined by dividing

o o X2-X2 by X^-X^ and multiplying by d to get the constant distance d bet- ween PDCx

2 and PDC

x o. 35
Cost

Per

Square

Foot

PDC yI1

PDC v o h

PDC YI

x

2

300 900

Area in Square Feet

where PDC = b^ + t^X, + b^

with X

2 fixed at three particular average wage rates

Figure 3.1 GRAPHICAL COST ESTIMATING PROCEDURE FOR A

HYPOTHETICAL WALL ABATEMENT TECHNIQUE.

36
in accuracy in estimating per unit costs with a specific curve, such as

PDCC nc , over that of another more standardized curve, say PDC r rn , 5.45 ' J 5.50

when the average wage rate is $5.45 per hour, is questionable. To avoid

attributing more precision to the model than exists, a standardized

graduation of 0.25 or 0.10 seems appropriate.

The ease with which this graphical cost estimating procedure can

be used can be demonstrated by applying a straightedge to Figure 3.1.

The straightedge is used to construct lines which, when read off the

verticle axis, give the predicted per unit direct cost. For example, to

return to the previous illustration, to find the per unit direct cost of

deleading N square feet of wall area, where 300 <_ N <_ 900, the value

corresponding to N is first found on the horizontal axis. A vertical

line, l-., is extended from N to the point where it intersects the appropriate average wage rate curve, PDCw , at N . From this point a horizontal line, i 25 is drawn until it intersects the vertical axis. This

point, P

N

, will give the per unit direct cost for the given area and

o

2 average wage rate.

It should be noted that the per unit direct cost lines are not extended indefinitely in either direction. Likewise the average wage rate

is not allowed to become arbitrarily small or large. The domain of defini

tion for both of these variables is constrained for two reasons. First,

extrapolating beyond the range of observation is unwise even if the

basic form of the model is correct. Second the model may no longer be

linear in these regions. However, when these constraints are recognized

procedures of this type which allow a qraphical solution are usually referred to as nomograms.

Productivity and contract package size are assumed constant. A

different family of curves will be associated with each set of assumo- tions about the values of productivity and contract package size.

37
and the model's underlying assumptions are satisfied, this procedure for

graphically estimating costs is both a simple and effective method for

computing per unit direct costs at the dwelling unit level.

3.5 Computational Cost Estimating Procedure

It was demonstrated in the previous section that the regression

model, in a slightly simplified form, could be plotted, thus allowing

costs to be estimated graphically. These nomograms were shown to be

both a simple and efficient method for estimating PDC. However, if the

nomograms are not already available, their construction requires that

some care be exercised to insure that the family of curves plotted

provides the desired information. As such it may be preferable to use a

more generalized procedure which involves the computation of PDC directly through the use of the regression model. It has already been shown

that the finalized form of the regression model was

PDC = 8 + P

1 X1 + 3 2 X2 + 3 3 X3 + 3 4

X 4 + e 3.4

where

X, = the quantity of surface deleaded,

X„ = the average wage rate,

X^ = the productivity of labor,

X. = the contract package size, and

e = the error term.

's 's Furthermore, when the estimated values of the 3. (b. ) are incorporated in the model, it may be written as

PDC = b + b,X, + b Q X + b_X~ + b.X.

.

3.5 11 2 2 3 3 4 4

In this form the model may be used to estimate PDC when the values of

determinants X-,, X„, X-, and X. are known.

For purposes of illustration, consider a dwelling unit where gypsum

veneer plaster is to be used to abate hazardous levels of LBP on 650

38
square feet of wall area. Assume that this dwelling unit is part of a

contract package which contains 15 dwelling units. Using this information, values for two of the determinants of direct cost can be assigned.

That is, the value for X, is 650 (the quantity of surface deleaded), and

the value for-X. is 15 (the contract package size). By referring to

Appendix C.l, where the values for the different determinants of direct

cost observed during Phase I are tabulated, an estimate of 12.6 square

feet per manhour for the value of X„ (the productivity of labor) is

selected. An estimate of X„ is taken from Appendix C.l since the productivity of labor is not usually known or easy to compute unless some

empirical data is available.

The value for X„ (the average wage rate) may be derived through the

application of the formula

AMR = P

] W1 + P

2 W2 + P

3 W3

, 3.9

where P, = the proportion of the total manhours expended by the plasterer.

P

? = the proportion of the total manhours expended by the painter,

P

3 = the proportion of the total manhours expended by the laborer,

W, = the wage rate of the plasterer,

hL = the wage rate of the painter, and

W~ = the wage rate of the laborer.

The values for the proportions P. were empirically estimated and found

to be: P, = 0.71, Pp = 0.19 and P

3 = 0.10. A sample of wages was taken

from the Phase I EHEP deleading operations involving the use of gypsum

veneer plaster for the different labor types. The values for the wages

of the different labor types were found to be: W = $7.25, W„ = $7.66

and W~ = $5.03. Thus the average wage rate may be expressed as

AWR = (0.71)($7.25) + (0. 1 9) ($7 .66) + (0.10)($5.03) = $7.11 3.10

Through the method of least squares, the estimates for the coefficients of the determinants of direct cost were found to be: b = 0.54,

b

] = -2.27xl0"

4

, b

2 = 0.11, b

3 = -0.02, and b4

= -8.1xl0"

3

. 39
With this information it is now possible to compute the direct cost

per square foot for this example using gypsum veneer plaster as the

abatement technique. Table 3.1 shows how the figures would be combined

to arrive at a PDC figure.

TABLE 3.1

COST ESTIMATING PROCEDURE FOR ABATEMENT OF LEAD-BASED PAINT ON

WALLS BY USE OF GYPSUM VENEER PLASTER

Determinant

Value

X

l 650

x

2 7.11

X

3 12.6

x

4

15

Coefficient

Value

b

0.54

b

l -4

-2.27x10

4

b

2 0.11

b

3 -0.02 -8.1xl0"

3

Product 0.54 -0.15 0.78 -0.25 -0.11

Summing the entries in the product row yields a direct cost per

square foot figure of $0.81. Thus, the direct cost of deleading 650

square feet of wall area with gypsum veneer plaster would be $526.50

(0.81x650) in this dwelling unit.

It should be noted that the values for the determinants of direct

costs used in this example are well within the minimum - maximum range

given in Appendix C.l , since exceeding these values could cause changes

in the model's structure and as such produce misleading results.

40
4. RESULTS OF DATA ANALYSIS BY BUILDING COMPONENT

AND ABATEMENT TECHNIQUE1

The analysis of the Phase I EHEP cost data was accomplished through

the use of a series of statistical procedures. These procedures permitted both the ranking of abatement techniques with regard to their

relative costs and the establishment of functional relationships between

the determinants of direct cost. These functional relationships once

established may in turn be used to estimate the direct costs associated

with a particular abatement technique. Since certain abatement tech2 niques may be used on several different building components, per unit

direct cost (P*DC) for that technique may vary across building components. Therefore, to improve the reliability of the estimate of PDC for

an abatement technique, functional relationships are developed for each

building component.

These functional relationships have associated with them both

structure and determinants. The model 's structure refers to the way in

which the determinants combine to produce a PDC figure, whereas determinants are taken here to mean specific variables which affect PDC. The

structure of all cost models presented in this section is linear.

Associated with each determinant (variable) is a coefficient by

which it is multiplied. Since the data available for analysis was

limited, the cost models presented in this section were developed

through statistical methods which estimate these coefficients. These

hhis chapter is designed so tha.t it may be read independently of

chapter 3. Hence some repetition of the topics discussed in chapter 3 is inevitable.

2 For example some paint removal methods can be used on doors, door

frames, windows and window frames and miscellaneous trim surfaces.

41
estimated coefficients taken together provide a means of predicting PDC

when values for the determinants (variables) are given.

There are four basic determinants of PDC which are dealt with in

this study: (1) the quantity of surface deleaded, (2) the average

wage rate, (3) the productivity of labor, and (4) the contract package

size. The quantity of surface deleaded provides a measure of how much

abatement work was done for a particular building component; it is equal

to the square feet of wall area, linear feet of trim or the number of

doors, door frames, or windows and frames deleaded in a given dwelling

unit. The average wage rate is that wage which would be paid on the

average per manhour over the complete abatement process for the particular building component. The average productivity of labor is equal to

that quantity of surface which can be deleaded in one manhour. The

contract package size is the total number of dwelling units being deleaded by the contractor who is performing the abatement work in the

dwelling unit under consideration.

The results of the analysis of each building component are presented in a series of three tables. These tables are intended to show

how direct costs vary, what statistical significance can be attached to

these differences, and what are the sources of these variations.

The first set of tables gives information on PDC, per unit labor

cost (PLC), and per unit material /equipment cost (PMC). The ranges of

the dfrect cost figures and the number of dwelling units in which the

abatement techniques were used are also presented in this set of tables.

At times differences in the way in which the abatement procedure was

performed indicated that a different set of measurement units would be

] Tables 4.1, 4.4, 4.7, 4.10, and 4.13,

42
preferable. For example, procedures for paint removal on doors, door

frames, and windows and frames, required that paint be removed to a

height of 5 feet above the floor in Washington whereas it was removed

only to a height of 4 feet above the floor in Atlanta. Thus to avoid

the introduction of systematic bias into the analysis of the cost figures, the unit of measure was taken to be linear feet of door or door

frame deleaded rather than the door or door frame itself. In the cases

where an alternative unit of measure was used, for example, some paint

removal methods on doors and door frames, direct costs were computed

using both measures. In the first set of tables the PDC, PLC and PMC

are designated with an (a) if they are on a per door or per door frame

basis and by a (b) if they are on linear foot basis. In this manner it

is possible to obtain a rough estimate of how paint removal methods

compare with replacement methods.

The second set of t?bles groups abatement techniques into categories with regard to their relative costs. This is performed in such a

way that PDC for those techniques falling in the same category are

judged to be not statistically different, whereas any techniques in a

different category are judged to have PDC's that are statistically

different.

The third set of tables provides estimates of the coefficients of

the determinants of PDC. To provide an indication of the relative

importance of these estimates, probabilistic levels of significance are

associated with them. Estimates are marked with an asterisk (*), two

asterisks (**), or an (n) to denote respectively significance at the 5%

1 Tables 4.2, 4.5, 4.8, 4.11, and 4.14.

2 Tables 4.3, 4.6, 4.9, 4.12, and 4.15.

43
level, 10% level, or no statistical significance. When the estimates of

the coefficients of the determinants of PDC are significant at either

the 5% or 10% level they provide two types of information about how PDC

varies. First, the value of the coefficient tells the magnitude of the

change in PDC for a given change in a specific determinant. Large

absolute values are an indication PDC is relatively sensitive to any

change in this determinant. Second, the sign of the coefficient tells

the direction of the change. For instance, a negative sign implies that

increasing the variable under consideration will result in a decrease in

PDC. Thus from the value and the sign of the estimated coefficient it

is possible to say, other things being equal, both how much and in what

direction PDC will vary for a given change in a specific determinant.

Associated with each model is also a coefficient of multiple determination. This gives an estimate of how completely the model explains

variations in PDC. Since the number of observations (the number of

dwelling units in which a particular abatement technique was used)

varied considerably, the coefficient of multiple determination adjusted

for both the number of observations and the number of variables used was

p p computed. This coefficient is denoted R . Values of R which are close

to 1.0 indicate that the model comes close to completely explaining

variations in PDC; values which are significantly below 0.5 indicate

that additional information would be useful and therefore predictions of

PDC from these models should be used with caution.

Before proceeding to the data analysis, it should be noted that the

cost figures presented in this section were derived from a specific set

of observations, namely Phase I of EHEP. The use of these figures to

estimate LBP abatement costs for cases which are statistically different

from this set could result in misleading figures. To facilitate the use

44
of the models presented in this report, guidelines to show under what

circumstances the model results are valid for the determinants of PDC

for each model are given in Appendix C.

4.1 Wall Abatement Techniques

Nine barrier methods were used to abate hazardous levels of LBP in

Phase I of EHEP. Four of these--veneer plaster, gypsum impregnated jute

fabric (gypsum jute), gypsum wallboard, and melamine panel ing--were used

in both the Washington and Atlanta portions of Phase I. Gypsum impregnated glass fabric (gypsum fiberglass) was used only in the Washington

portion of Phase I; and cementitious coating, filled paint, vinyl-coated

fabric, and plaster with metal lath were used only in the Atlanta

portion of Phase I

.

The average PDC, PLC, and PMC figures for each of these techniques

as well as their ranges are given in Table 4.1. Average direct costs

for the various abatement techniques were found to range from a low of

$0.20 per square foot for cementitious coating to a high of $1.65 per

square foot for melamine paneling.

The wall abatement techniques were then tested to see if some form

of grouping with regard to their relative costs was possible. The results of these tests are given in Table 4.2. The statistical grouping

of wall abatement techniques resulted in 4 categories: (1) cementitious coating and filled paint (painting techniques); (2) veneer plaster, gypsum fiberglass, gypsum jute and gypsum wallboard (mixed techniques); (3) plaster with metal lath (plastering technique); and (4)

melamine paneling (paneling technique). The grouping in this case also

demonstrates that some techniques in the same category exhibit similarities in the method of application.

1 Vinyl -coating fabric was not included in this portion of the analysis

because it was used in only one dwelling unit.

45
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46
TABLE 4.2

RANKING OF WALL ABATEMENT TECHNIQUES BY

AVERAGE DIRECT COST

CATEGORY

ABATEMENT TECHNIQUES GROUPED BY

SIMILARITY OF MEANS3

AVERAGE DIRECT COST

PER SQUARE FOOT

1 Cementitious Coating

Filled Paint

$0.20

$0.21

2 Veneer Plaster

Gypsum Fiberglass

Gypsum Jute

Gypsum Wall board

$0.74

$0.77

$0.79

$0.92

3 Plaster with Lath $1.31

4 Mel amine Paneling $1.65

Those techniques falling in the same category are judged to be not

statistically different while there does exist a statistically signi

ficant difference between categories.

47
The estimates of the coefficients of the determinants of direct

cost are given in Table 4.3. It should be noted that in the case of

category 1 abatement techniques the only satisfactory estimate of direct

cost per square foot was the arithmetic average which is given in the

intercept column. In cases where more than one coefficient are being

estimated, the intercept term does not equal the average or constant

PDC. For these cases the inclusion of the intercept term is of an

algebraic rather than an economic interest. Upon closer examination it

can be seen that some patterns across categories have emerged. For

example, an increase of 100 square feet of wall area deleaded, other

things being equal, causes a decrease in direct cost per square foot of

2.3<fc for the category 2 abatement techniques, 6.2<t for plaster with

lath, and 19<t for mel amine paneling. On the other hand, increasing the

average wage rate by $1.00 per manhour translates into an increase of

10. 6£ per square foot for the category 2 abatement technqiues, 73.2<£ for

plaster with lath, and 66.9<£ for melamine paneling. In the cases where

contract package size was used as a variable, its coefficient implied

that increasing the contract package size would decrease direct cost per

square foot. From Table 4.3 it can be seen that the rate at which

direct cost per square foot changes as either the area or the average

wage rate changes is significantly higher for the category 3 and category 4 wall abatement techniques than for those in category 2. This

high rate of change is most probably caused by the high degree of labor

intensity of these techniques. For instance, increasing area can result

in scale efficiencies. Similarly, due to the high degree labor intensity,

Contract package size was not used as a variable for every category

since some abatement techniques were used only in one city. In some of

these cases there was little or no variation in contract package size.

48
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49
the category 3 and category 4 abatement techniques are sensitive to any

changes in the wage rate. The direct cost per square foot may also be

affected by changes in the productivity of labor. Category 2 abatement

techniques can be seen to be relatively sensitive to changes in productivity in that an increase in the productivity of labor of 1 .0 square

foot per manhour will cause a reduction in direct cost per square foot

of approximately 2<£. The coefficient of multiple determination adjusted

to reflect both the number of observations and the number of variables

used indicates that PDC's per square foot estimated using either the

category 2, 3 or 4 cost models are fairly reliable. PDC estimates for

category 1 abatement techniques are merely averages and hence should be

used with caution until more data has been collected on these techniques.

4.2 Door Abatement Techniques

Eight door abatement techniques were used in Phase I of EHEP.

Four of these--the replacement of interior doors, paint removal through

the use of a heat gun, paint removal by solvent stripping, and paint

removal by the dip tank method--were used in both the Washington and

Atlanta portions of Phase I. Four techniques, the replacement of exterior and screen doors and paint removal through the use of an infra-red

device and by hand scraping, were used only in Atlanta.

The average PDC, PLC, and PMC figures, as well as their ranges are

given in Table 4.4. Since differences in the height to which doors were

The productivity of labor was not used as a variable in the model

for plaster with lath since it was highly correlated with the average

wage rate. It was not used in the model for mel amine paneling since only

five observations were used in the analysis and there were already four

coefficients being estimated.

50
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51
abated above the floor differed between Washington and Atlanta the cost

2 per linear foot of door abatement has also been computed.

The door abatement techniques were then tested to see if some form

of grouping with regard to their relative costs was possible. Table 4.5

shows the two categories that resulted from this test, paint removal

methods and the replacement of components. The grouping of door abatement techniques indicate that the PDC for the dip tank method is similar

to those of the other category 1 abatement techniques. For the purpose

of estimating the coefficients of the determinants of direct cost,

however, the dip tank method was separated from the other category 1

abatement techniques. This was done since the dip tank method removes

LBP from the entire door whereas the other category 1 techniques only

remove LBP from the door stiles. Also, by separating the dip tank

method from the other category 1 abatement techniques, it was possible

to develop direct cost estimates per linear foot of door deleaded,

The estimates of the coefficients of the determinants of direct

cost are given in Table 4.6. Some of the patterns which emerged from

the data for wall abatement techniques are again present. For instance,

an increase in the number of units processed (number of doors or linear

feet of door deleaded) causes PDC to decrease. It should be noted that

PDC's for replacement methods and to some extent the dip tank method are

considerably more sensitive to any change in the number of units processed than are the PDC's for the paint removal methods. This reflects

both the higher labor and material/equipment costs associated with these

Doors were deleaded to a height of 5 feet in Washington, whereas

they were deleaded only to a height of 4 feet in Atlanta.

Computations of the direct costs, labor costs, and materials/

equipment costs per linear foot for door abatement techniques appear

on lines marked (b) of Table 4.4.

52
TABLE 4.5

RANKING OF DOOR ABATEMENT TECHNIQUES BY

AVERAGE DIRECT COST

CATEGORY

ABATEMENT TECHNIQUES GROUPED BY

SIMILARITY OF MEANS^

AVERAGE DIRECT COST

PER DOOR

1

1A

Scrape and Sand

Heat Gun

Solvent Strip

Dip Tank

$13.02

$18.91

$25.38

$56.47

2 Replace Interiors

Replace Screen

Replace Exteriors

$94.57

$123.15

$130.96

Those techniques falling in the same category are judged to be not

statistically different while there does exist a statistically significant difference between categories.

53
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54
abatement techniques (see Table 4.4). As with wall abatement techniques, increasing the average wage rate causes direct costs to increase. The effect on PDC of a given change in the average wage rate is

significantly larger for the dip tank and component replacement methods

than for the category 1 (paint removal) abatement techniques since the

former methods are more labor intensive. The value of the estimate of

the coefficient of productivity indicates that the PDC's are sensitive

to any change in the productivity of labor. Since some of the abatement

techniques used in Phase I were relatively unfamiliar to the construction industry there may be a learning process through which the productivity of labor can be increased to such a point that the PDC's are

significantly reduced. One anomaly which has occurred with this set of

data concerns the sign of the coefficient of contract package size.

Since the sign is positive, it indicates that larger contract packages

result in a higher PDC. It should be noted however, that the estimate

for contract package size is (statistically) not significantly different

from zero for the dip tank and component replacement methods. It is

significant at the 10% level for category 1 abatement techniques.

However, this is more a reflection that doors were deleaded to five feet

2 above the floor in Washington where large contract packages were observed and only four feet above the floor in Atlanta where smaller

3 contract packages were observed. When the unit of measure is changed

Hhe number of manhours expended per unit for category 1A and 2 abatement techniques is roughly 2 to 4 times that for category 1 abatement techniques.

2 All dwelling units deleaded in Washington were done by the same con- tractor, so that the contract package size was equal to 30.

3The contract package size in Atlanta varied from 1 to 16 dwelling

units.

55
from the number of doors to the linear feet of door deleaded, the differences in the abatement procedures between Washington and Atlanta are

resolved. Under these conditions the coefficient of the contract package size is (statistically) no longer significantly different from zero.

R has also reacted favorably to this change in the unit measure, indicating that this measure permits a greater percentage of PDC to be

explained. The values of R for categories 1A and 2 indicate that PDC

estimates for the dip tank method (1A) are ^jery reliable but that estimates of PDC for component replacement techniques (2) should be used

with caution.

4.3 Door Frame Abatement Techniques

Five door frame abatement techniques were used in Phase I of EHEP.

Three of these—the replacement of exterior components, paint removal by

means of a heat gun, and paint removal by solvent stripping —were used

in both the Washington and Atlanta portions of Phase I. Two paint

removal techniques, hand scraping and an infra-red device, were used

only in Atlanta.

The average PDC, PLC, and PMC figures as well as their ranges are

given in Table 4.7. Since door frames were deleaded to a height of 5

feet above the floor in Washington, but only to 4 feet above the floor

in Atlanta, direct costs per linear foot were computed.

The door frame abatement techniques were then tested to see if some

form of grouping with regard to their relative costs was possible.

Table 4.8 gives the results of these tests. Two categories resulted

from this grouping procedure, reflecting differences in relative costs

Table 4.7 gives on lines (a) the direct costs per door frame

deleaded and on lines (b) the direct costs per linear foot of door

frame deleaded.

56
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TABLE 4.8

RANKING OF DOOR FRAME ABATEMENT TECHNIQUES BY

AVERAGE DIRECT COST

CATEGORY

ABATEMENT TECHNIQUES GROUPED BY

SIMILARITY OF MEANSa AVERAGE DIRECT COST

PER DOOR FRAME

1 Scrape and Sand

Heat Gun

Infra-Red Device

Solvent Strip

$12.08

$18.30

$22.30

$22.66

2 Replacement (Exterior) $98.45

Those techniques falling in the same category are judged to be not

statistically different while there does exist a statistically significant difference between categories.

58
between paint removal methods (category 1) and the replacement of

components (category 2).

The estimates of the coefficients of the determinants of direct

cost are given in Table 4.9. The PDC for door frames differs from that

for doors for component replacement in that it increased by $2.85 for

each additional door frame replaced. The PDC for paint removal methods

also increased, but only by 4<t for each additional door frame. This

figure in addition to being relatively small is (statistically) not

significantly different from zero. When direct costs for the paint

removal methods (category 1) were estimated on the basis of linear feet

abated, increasing the linear feet abated does result in a decrease in

PDC. However the coefficient was still (statistically) not significantly different from zero. For both category 1 and category 2 abatement techniques increasing the average wage rate, other things being

equal, increased the PDC. As would be expected, component replacement

exhibits considerably more sensitivity to changes in the average wage

rate. Increases in the productivity of labor cause PDC to decrease for

both component replacement and paint removal methods. But the sensitivity of component replacement to changes in the productivity of labor

is considerably higher than that for the paint removal methods. The

sensitivity exhibited by component replacement to both changes in the

productivity of labor and the average wage rate highlights the fact that

replacement of components is a labor intensive process. Varying contract package size produces slightly different results for component

replacement methods than for paint removal methods; increasing the

contract package size by 1 dwelling unit decreases the PDC by $2.53.

This in part reflects a rather sizable difference in PDC between Washington ($73.32), where larger contracts were observed, and Atlanta

59
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60
($114.44), where smaller contracts were observed. This may be an

indication that larger contract packages for door frame replacement

methods permit more efficient scheduling of resources. For paint

removal methods an increase in contract package size causes PDC, taken

on a per door frame basis, to increase. However, when the coefficient

was reestimated on a linear foot basis to take into consideration the

differences in abatement procedures between Washington and Atlanta, the

coefficient was (statistically) no longer significantly different from

zero although the sign remained positive. The relatively high values of

_2

R^ demonstrate that the models given in Table 4.9 are quite complete in

the estimation of PDC for both paint removal (category 1), and component

replacement (category 2) methods. The higher value of R resulting from

estimating PDC on a linear foot basis for category 1 abatement techniques indicates that the linear foot measure is preferable to the per

door frame measure.

4.4 Window and Window Frame Abatement Techniques

Five window and window frame abatement techniques were used in

Phase I of EHEP. Three of these--the replacement of wooden windows and

window frames, paint removal by the use of a heat gun and paint removal

by solvent stripping—were used in both the Washington and Atlanta

portions of Phase I. Two paint removal techniques, the use of an infrared device and hand scraping, were used only in Atlanta.

The average PDC, PLC, and PMC figures along with their ranges for

the Phase I window and window frame abatement techniques are outlined in

Table 4.10.

The productivity of labor was also higher in Washington, 0.137

door frames per manhour, than in Atlanta, 0.095 door frames per manhour.

61
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62
The window and window frame abatement techniques were then tested

to see if some form of grouping with regard to their relative costs was

possible. The results of these tests are given in Table 4.11. From

Table 4.11 it can be seen that the window and window frame abatement

techniques can be grouped into two categories: (1) paint removal

methods, and (2) component replacement. As with door and door frame

abatement techniques, the procedure for the removal of LBP from windows

and window frames differed between Washington and Atlanta, being deleaded to a height of 5 feet in Washington but only to a height of 4

feet in Atlanta. The data on windows and window frames unlike that for

doors and door frames did not permit a realistic estimate of the number

of linear feet deleaded since the height of the window sill above the

floor and the width of the opening was not available. An estimate of

the cost of deleading an extra foot of height was made for the various

paint removal methods. The inclusion of this new variable, however,

tended to complicate rather than simplify the problem of estimating PDC,

so it has been omitted from the analysis presented here.

Some of the difficulties caused by deleading an extra foot of

height in Washington become apparent when the estimates of the coefficients of the determinants of direct cost given in Table 4.12 are

studied. For example, the PDC for paint removal methods (category 1)

increases as the number of units processed increases. This reflects two

things. First, the number of windows and window frames deleaded per

dwelling unit for all paint removal methods was 5.4 in Atlanta versus

6.6 in Washington. That is, the larger values for the number of units

processed are associated with the Washington observations. Second, the

average direct costs per window for the heat gun and solvent stripping

63
TABLE 4.11

RANKING OF WINDOW AND WINDOW FRAME ABATEMENT TECHNIQUES

BY AVERAGE DIRECT COST

CATEGORY

ABATEMENT TECHNIQUES GROUPED BY

SIMILARITY OF MEANSa AVERAGE DIRECT COST

PER WINDOW AND FRAME

1 Scrape and Sand

Infra Red

Heat Gun

Solvent Strip

$22.87

$28.06

$29.50

$38.67

2 Replacement $128.82

Those techniques falling in the same category are judged to be not

statistically different while there does exist a statistically significant difference between categories.

64
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65
1 2 techniques in Washington were higher than in Atlanta. For both paint

removal and component replacement methods, increases in the average wage

rate cause PDC to increase and increases in the productivity of labor

cause PDC to decrease. The replacement of windows and window frames are

^jery sensitive to small changes in either the average wage rate or the

productivity of labor. Again this is probably due to the labor intensive nature of the component replacement process. The coefficient of

contract package size also has a positive sign indicating higher PDC's

are associated with larger contract packages. This again reflects the

fact that the large contract packages were observed in Washington. In

looking at window replacements, the rather large (2.32) coefficient of

contract package size does not seem correct, since the PDC was lower in

Washington ($116.15) than in Atlanta ($137.33), and the number of windows and window frames replaced per dwelling unit was higher in Washington (5.4) than in Atlanta (2.2). Moreover, the per unit direct costs

for Washington were much more variable ($48.79 - $227.11) than for

Atlanta ($105.61 - $161.81). Contract package size was also slightly

correlated with both the average wage rate and the productivity of

labor so that a portion of the variation in PDC has already been taken

up in the estimation of these coefficients. The R for each category is

relatively high indicating that these complications have not seriously

interfered with the models ability to estimate PDC. Since some of the

problems which arose in the analysis of this set of data were not resolved,

These were the only paint removal methods which were used in both

Washington and Atlanta.

2 Though the PDC for Washington is higher than Atlanta it is not

possible to say how much of this difference is due to the extra foot of

height of window and frame deleaded.

66
however, caution should be exercised in the use of these models to

predict PDC for abatement of LBP on windows and window frames.

4.5 Abatement Techniques for Miscellaneous Trim Components

During Phase I, LBP was removed from trim surfaces by means of hand

scraping, solvent stripping or through the use of the following special

equipment: heat gun, infra-red device, and propane torch. The abatement of miscellaneous trim surfaces was done only in the Atlanta portion

of the program. The average PDC, PLC, and PMC figures associated with

each abatement technique for miscellaneous trim components are outlined

in Table 4.13.

The abatement techniques for miscellaneous trim components were

then tested to see if some form of grouping with regard to their relative costs was possible. Table 4.14 gives the results of these tests.

From Table 4.14 it can be seen that no statistically significant differences exist between the direct costs per linear foot for these abatement

techniques.

The estimates of the coefficients of the determinants of direct

cost are given in Table 4.15. Several interesting points can be seen

from this table. First, if quantity of trim deleaded in a dwelling unit

increases by 50 linear feet the direct cost per linear foot decreases by

about 15£. Second, an increase in the average wage rate of $1.00 per

hour causes direct cost to increase by approximately 20<fc per linear

foot. A one foot per manhour increase in the rate at which trim can be

deleaded (an increase in the productivity of labor) reduces direct cost

by 19<£ per linear foot. Finally, the use of a heat gun, an infra-red

device, or a propane torch, denoted here as special equipment to remove

Miscellaneous trim components denote such items as baseboards,

handrails, and molding.

67
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68
TABLE 4.14

RANKING OF TRIM ABATEMENT TECHNIQUES BY

AVERAGE DIRECT COST

CATEGORY

ABATEMENT TECHNIQUES GROUPED BY

SIMILARITY OF MEANS3

AVERAGE DIRECT COST

PER LINEAR FOOT

1 Solvent Strip

Scrape and Sand

Propane Torch

Heat Gun

Infra-Red

$1.77

$1.90

$2.34

$2.84

$3.24

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statistically different while there does exist a statistically signi

ficant difference between categories.

69
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70
LBP, causes direct cost to increase by 85<fc per linear foot. The value

of R of 0.48 indicates that the model has been able to in capture only

about half of the variation in PDC. One omitted element which is

likely to affect PDC is the occupancy status of the dwelling unit.

Although both occupied and unoccupied dwelling units had trim deleaded, a

dummy variable for occupancy has not been included for two reasons.

First, although not by design all occupied units were done by union

scale labor and unoccupied units by nonunion scale labor; thus average

wage rate would be highly correlated with this variable. Second, the

quantity of trim deleaded was significantly larger in the unoccupied

units than in the occupied, thus the linear feet of trim deleaded would

also be correlated with occupancy status. Once these constraints are

recognized, however, the model may be used to provide a baseline estimate which will probably be slightly high if the dwelling unit is unoccupied and probably a little low if it is occupied.

71
5. SUMMARY AND RECOMMENDATIONS FOR FURTHER RESEARCH

5.1 Summary

The potential of lead poisoning through the ingestion of lead-based

paint (LBP) chips is a serious threat to the health and well-being of

young children. As such, this problem has stimulated interest in both

the public and private sectors into ways in which the hazards of LBP

could be eliminated from the nation's housing. A method for estimating

the costs of LBP abatement is required to insure that the resources

devoted to eliminating the hazards of LBP will be used efficiently.

This study develops a series of cost models for the estimation of

the direct costs of LBP abatement. Direct costs were analyzed at the

dwelling unit level by building component (walls, doors, door frames,

windows and frames, and miscellaneous trim) and abatement technique.

They were compared on the basis of per unit direct cost (PDC), that is,

the direct cost per item, per square foot, or per linear foot, to determine whether some form of ranking was possible. If significant differences in PDC existed, the abatement techniques were grouped into cost

categories ranked from least expensive to most expensive. These categories were designed so that abatement techniques in the same category

had roughly equal PDC's whereas those in another category had significantly higher or lower PDC's. Furthermore, it was frequently the case

that techniques in the same category were also similar in the procedure

they used to abate LBP. Once the abatement techniques were grouped into

categories, the variables which accounted for variations in PDC were

analyzed; estimates of how these variables affected PDC, both the magnitude and the direction of the change, were also developed. The estimates were then combined to form a cost model which permitted the prediction of PDC's for each abatement technique.

72
To provide a measure of the confidence with which the LBP abatement

cost models can be used, a statistical estimate of how complete the

model is at explaining variations in PDC was presented. These statistics took on values which ranged from 0.43 to 0.94 for the eleven separately estimated cost models; the average value was 0.71. That is, on

the average, 71% of the variation in PDC was explained by a linear cost

model. It should be noted that the estimate of how complete the model

was at explaining variations in PDC exceeded 0.70 for eight of the

eleven models. Three models did have values of this statistic between

0.43 and 0.50, however, which pulled the average down somewhat. The

reason for these lower values can be attributed, at least in part, to

difficulties in separating variations in PDC due to the affects of union

versus nonunion pay scales and occupancy status. When more data becomes

available on these abatement techniques, it seems likely that the completeness with which variations in PDC can be measured (and predicted)

will be significantly increased. Thus most of the cost models developed

in this study provide a reliable direct cost estimating procedure for

both public and private decision makers faced with LBP abatement in

housing. Furthermore, most of the cost models which were developed in

this study are of a general enough nature that they have captured potential differences in PDC due to regional effects. For example, any

constraints which may result from special pay scales or limitations on

the amount of work which can be performed in a work day are included, or

can easily be incorporated, within the model 's framework.

An alternative cost estimating method is also discussed which

permits the decision maker to estimate PDC through the use of a graphical procedure.

Since the methods used for LBP abatement can also be used in the

rehabilitation or renovation of housing, these cost models provide a

73
means for readily obtaining baseline estimates for PDC in the rehabilitation of either a single dwelling or a contract involving as many as 25

to 30 dwelling units.

5.2 Recommendations for Further Research

In order to expand the cost models developed in this study to include total project costs, to determine the optimal combination of LBP

abatement techniques, and to gain a fuller knowledge of what policy

options are most likely to be both economically and socially acceptable,

further research on several topics would be useful.

Since the emphasis of this study was on direct costs, the cost

models developed did not provide a measure of total project costs.

Total project costs, which are being assessed in Phase II of EHEP and

include markup, will probably influence the economically optimal level

of LBP abatement in that markup may vary as a function of ownership (for

example HUD, a local housing authority, or a private individual) or the

number of dwelling units having abatement work done (the contract package size)

.

Due to the lack of information on building repairs, it was not

possible to assess the effect that repair costs had on the different LBP

abatement techniques. Since repair costs enter into the determination

of PDC in different ways for different abatement techniques, it is

useful to know how the introduction of these costs will affect the

choice of an optimal combination of LBP abatement techniques. Nor was

it possible to ascertain the extent to which direct costs would change

as a function of occupancy status. The resolution of these problems,

which are being addressed in Phase II of EHEP, should significantly

improve the accuracy with which direct costs can be estimated. In this

report it was demonstrated that, for some trim abatement methods, better

74
PDC estimates could be achieved if costs were recorded on a linear foot

basis rather than a per item basis. This method of recording data is

also preferable in that regulations for the height to which LBP should

be removed vary from city to city. Therefore, if estimates based on a

linear foot measure are available, they provide a means for estimating

direct costs independent of local regulations.

This study has not focused on the benefits to be derived from LBP

abatement. The establishment of what benefits are associated with LBP

abatement and their quantification is essential to the identification of

an optimal combination of LBP abatement techniques. Furthermore, the

estimation of total project benefits may also be used as a tool in the

development of alternative LBP abatement strategies at the national

level. Developing such estimates in future research will reduce the

probability of the rejection of an LBP abatement strategy which is

optimal or of the acceptance of a strategy which is economically less

than optimal

.

Previous studies have determined the types of housing which were

most likely to contain LBP. At present, however, only crude estimates

are available for the number of each type, which are occupied or awaiting occupancy, and what effect current housing trends will have on this

number and hence how potential benefits would be affected. It would be

helpful if better estimates were available.

It might also be useful to investigate incentives programs which

could be used to eliminate the LBP hazard. Such incentives could include financing LBP abatement through low-interest loans or some form of

cost-sharing. Analyses such as these could provide public and private

decision makers with the information necessary to make the efficient

choice among competing policy alternatives.

75
APPENDIX A: DESCRIPTION OF ABATEMENT TECHNIQUES

This appendix is intended to supply background information on the

three basic methods of lead-based paint (LBP) abatement. The three

abatement methods are subdivided into individual abatement techniques.

The abatement techniques are then described individually in some detail

with regard to their composition, method of application, and/or any

special skill or material /equipment requirements.

Since the body of this appendix is formed of excerpts from publications in which these abatement techniques are described in greater

detail , the interested reader is referred to the two reports by Boone

et a!.

1

A.l Paint Removal Methods

The safety of workmen and dwelling occupants is a primary consideration in the implementation of paint removal methods. Procedures should

be taken to avoid the inhalation or absorption of lead fumes or dust.

In addition attention should be given to the potential fire hazard

associated with the use of open flame paint removal techniques.

A. 1.1 Solvent-Based Paint Removers

A number of "industrial grade" paint removers may be used to remove

LBP from windows, doors and other wood trim and components. These normally viscous liquids are applied to both horizontal and vertical surfaces by brush, allowed to react with the lead paint coatings and then

removed along with the softened paint using various metal scrapers.

Paint removers are extremely variable in their ability to penetrate

and react with multiple layers of dried paint. The effectiveness of the

The Demonstration of Experimental Lead Paint Hazard Abatement

Methods in Washington, D.C. , and The Demonstration of ExperimentaTTead

Paint Hazard Abatement Methods in Atlanta, Georgia.

76
remover depends not only on its own composition but also on the nature

of the multi-layered coating to which it is applied. Most removers will

react with only 2 to 4 layers of paint at a time. In such cases, where

more than that number of layers of paint is present, the remover-paint

agglomeration must be removed and fresh remover applied as often as

necessary to achieve complete removal.

Generally, the reaction time for paint removers is about one-half

hour. The remover-paint waste, which is scraped from the treated surfaces, is collected on polyethylene drop cloths and discarded. Prior to

light sanding and repainting, the surface is wiped with a watersaturated rag in order to remove any residue of remover-paint mixture.

Proper precautions regarding open flames, adequate ventilation and

avoidance of contact with skin is necessary to assure the safe use of

this class of products.

A.l .2 Hand Scraping

Simple hand tools such as paint scrapers and putty knives may be

used to remove loose and flaking paint. Electrical sanders may then be

used to achieve the complete removal of paint which adhered too tightly

to those surfaces for hand scraping.

A. 1.3 Electrical Heat Gun

When paint is heated sufficiently, it softens, swells and usually

blisters so that it can be removed easily from its substrate with metal

scrapers. Several techniques are available for removing paint from

doors, windows and other wood surfaces, by means of heat generation.

One such technique, a portable flameless electric hot air blowing

device is quite effective in removing paint from wood substrates as

demonstrated in laboratory tests; it also presents an apparent low risk

of fire and injury to the operator or bystanders.

77
This commercially manufactured device consists essentially of an

air blower attached to a reinforced flexible plastic hose, with a cylindrical electric heater at the outlet. The heater is heavily insulated,

so that it can be hand held while in operation. This apparatus is

mounted on a stand which is quite mobile. It is capable of producing a

strong stream of hot air at temperatures of between 350° and 1000°F

(175° and 540°C). The working end of the device is very light in weight

and a single workman can perform the continuous operations of heating

the paint to its softening point and scraping it off with metal tools.

Electrical circuits or portable generators supplying 20 ampere currents

at 110-120 volts are required for operation of the hot air blower.

A. 1.4 Infra-Red Heat Device

The infra-red heat device used in the Atlanta portion of EHEP

consists of a propane burner whose flame is recessed in a metal reflector covered with a metal grid. When the flame is lit, the grid is

heated. The device is held near the surface that is to be stripped and

the heat radiating from the grid softens the paint so that it can be

scraped off with metal tools.

This device is somewhat less hazardous than a propane torch because

the open flame is recessed. It is completely portable, uses one pound

disposable propane cylinders or a 25 pound refillable propane tank. The

process of heating and scraping can be carried out by a single workman.

A.l .5 Propane Torch

The open flame produced by a propane torch can be used to heat

paint directly to the softening point so that it can be scraped off with

metal tools. The process is easily carried out by a single workman

using a one pound propane bottle.

Until recently, the use of propane torches had been quite widespread for this purpose. They are now falling into disfavor, however,

78
due to the extreme fire hazard of an open flame (especially in occupied

and furnished dwellings) and the danger of over-heating paints to the

point of vaporization of the lead pigments. As a safety precaution its

use in the Atlanta portion of EHEP was restricted to the stripping of

exterior wood trim surfaces.

A.l .6 Dip Tank Method

Commercial furniture stripping plants have facilities for removing

old paint and varnish by totally immersing the object of interest in

large tanks containing heated alkaline solvents in an aqueous medium.

Doors may be stripped by this process, requiring two to three hours

of treatment during which time they are alternately soaked and scrubbed

with heavy bristle brushes. The total stripping time is dependent on

the type of paint, the number of paint layers and the temperature and

strength of the solvent bath. Doors can be stripped with hinges and

other hardward still attached. After the paint is completely removed

the doors are washed with water, allowed to air dry and then returned to

the dwelling from which they were taken where they are reinstalled and

repainted.

A. 2 Replacement of Components

Removal of doors, door drames, windows and frames, and other trim

components and replacement with new materials is an accepted technique

of LBP abatement. Replacement is used primarily when building components are deteriorated or damaged beyond the point of functionality and

due to their poor condition the cost of abatement by other means would

be prohibitively expensive. This method in addition to restoring the

building component to functionality also provides an opportunity to

upgrade the quality of the dwelling unit significantly.

79
Carpentry skills are required for rehanging, fitting and remounting

hardware. Custom carpentry may be required for replacing wooden sash

windows and frames in some dwelling units.

A. 3 Barrier Materials

The complete stripping of LBP from surfaces or the removal and

replacement of building components which are coated with LBP can unequivocally be defined as LBP elimination methods. The effectiveness of

such methods is essentially total. However, the application of those

methods to large wall surfaces appears to be both impractical and prohibitively expensive. The application of materials, which are intended

to act as barriers is frequently the most reasonable approach to the

abatement of LBP on planar surfaces. The effectiveness of barrier

materials is a function of the degree to which they prevent access to

the existing lead paint which they cover. The material's strength,

durability and permanence are the primary characteristics that establish

its effectiveness in LBP abatement.

A. 3.1 Cementitious Coating

The cementitious coating consists of portland cement, sand, and

acrylic resin to which water is added to make a slurry. It can be

tinted to desired colors by the addition of pigments recommended by the

manufacturer.

The cementitious coating is viscous and it has a rough texture. It

can be applied by brush or roller or any other equipment designed to

apply viscous filled coatings.

The surface to be coated must be clean and free from loose particles. Glossy surfaces must be roughened with an abrasive and chaulky

surfaces sealed with a sealer to ensure good adhesion. The applied

coating has a final thickness of about 1/16-inch (about 1.6 mm).

80
A. 3. 2 Aggregate Filled Paint (Filled Paint)

This coating is a latex based product which contains sand or other

mineral aggregate which provides a thick finish comparable in texture to

sand finished plaster.

Filled paint is viscous. The product used was formulated for

application by airless spray equipment but it, and most other formulations, can be applied using a brush or roller. It requires no mixing

or thinning and it can be applied successfully to any surface which is

free of dirt, oil or grease. Primers are not required for use on previously painted surfaces and thicknesses as high as 20 mils (0.02 inch

or 0.05 cm) can be obtained with one coat. The finish texture, ranging

from smooth to coarse, depends upon the aggregate quantity and particle

size.

A. 3. 3 Gypsum Impregnated Jute Fabric (Gypsum Jute)

This wall covering product consists of jute fabric which is impregnated with uncrystallized gypsum (hydrated calcium sulfate). It is

applied to walls, in the same manner as wallpaper, with a water base

adhesive which is recommended by the manufacturer of the fabric. As the

gypsum absorbs moisture from the air, it hydrates, hardens and becomes a

fairly rigid and penetration-resistant material. A protective coating

can be applied if the material is to be used in wet areas.

A clean substrate, in good repair, is necessary for adequate adhesion. The covering will, however, bridge minor voids and mask minor

substrate imperfections.

A. 3. 4 Cement Impregnated Glass Fabric (Gypsum Fiberglass)

This product is similar in appearance to the gypsum jute fabric

described above. It consists of glass fabric impregnated with Portland

cement and develops into a rigid, strong material by absorbing moisture

81
from its environment. The general comments regarding method of application, intended use and finishing are the same for this product as for

the previous one.

A. 3. 5 Vinyl -Coated Fabric

Vinyl-coated fabric is basically similar to wallpaper or vinyl-clad

paper. Its strength and durability exceeds that of the other two

materials because of its combination of vinyl surface and textile fabric

backing.

Vinyl -coated fabric may be installed on any wall surface that is

free of dirt, grease, oil and moisture. The method used for hanging

vinyl -coated fabric is the same as used for hanging wallpaper. The

adhesive used depends upon the weight of the vinyl coated fabric. These

fabrics normally resist soiling and staining even by objects such as

crayon, lipstick, or ink. A mild detergent and a sponge usually will

remove most soils and stains. They conform to the bends and contours of

most surfaces and are installed readily by workmen who are familiar with

wallpaper installation using ordinary hand tools and equipment.

A. 3. 6 Gypsum Veneer Plaster

This product is a component pre-packaged material which becomes

plastic when mixed with water so that it can be trowel applied to form a

highly polished finish or can be worked to achieve a textured finish.

It may be applied to solid plaster walls which have first been treated

with a vinyl polymer bonding compound to improve adhesion to the existing painted surfaces. The finished thickness of the plaster is approximately 1/8-inch (3.2 mm) thick. Skilled workmen are required for the

satisfactory application of this product.

A. 3. 7 Gypsum Plaster with Metal Lath

Gypsum plaster is applied to a metal lath which serves as a support

for the plaster and a means of adhesion to the surface being treated.

82
The lath is a netting of 20 gauge galvanized steel which is fastened to

a surface with nails, staples or screws.

The plaster is usually applied in two stages resulting in a final

thickness of 1/2-inch (1.3 cm). In the first application, wood fiber is

added to the gypsum plaster to improve its working characteristics by

making it easier to apply and to increase its adhesion to the metal

lath. This first coat is applied by trowel to a uniform thickness of

about 3/8-inch (1 cm). The plaster sets up (hardens) rapidly and must

be applied quickly. Highly calcined gypsum plaster is used for the

second or top-coat. This plaster contains a retarder which delays

hardening so that the desired finish (smooth or textured) can be achieved. The final coat is about 1/8-inch (0.3 cm) thick. The finished

dried surface is usually painted.

The application of plaster to lath should be done by skilled workmen. The temperature of the work area and surface should be above 50°F

and adequate ventilation (for proper drying of the plaster) should be

provided.

A. 3. 8 Gypsum Wall board

Gypsum wall board is a product which is composed of a thick layer of

gypsum to which paper or other materials are bonded to provide a finished or finishable surface. It is intended for use on walls, ceilings,

or partitions and can be applied directly to existing surfaces or to

wood or metal furring strips.

It can be applied directly to existing walls with adhesives and

nails. The installed wallboard is prepared for painting by finishing

the joints between the sheets with joint tape and compound. Nail heads

are then covered with compound and both areas are sanded to a smooth

finish.

83
A. 3. 9 Plywood on Floors

Plywood may be used to cover-up lead painted exterior wood decks on

porches. Warped and rotted boards are replaced with new or sound ones

and a 15 lb. (6.8 kg) roofing felt is put down as an underlayment before

installing the plywood.

Four by 8 foot (1.2 x 2.4 m) sheets of 3/8-inch (9.5 mm) A-B grade,

exterior or marine plywood is used. All edges are treated with wood

preservative and the sheets are nailed or screwed to the existing deck

with its A grade surface up. All exposed edges are covered with wood

trim and the new surface is painted with one coat of primer and two

coats of exterior paint.

Skilled workmen are required to install plywood on existing porch

decks with satisfactory workmanship. Although the job can be done with

hand tools it can be accomplished much more easily with ordinary power

tools such as electric drills and saws.

A. 3. 10 Mel amine Coated Hardboard

This product is a 1/4-inch (6.4 mm) thick tempered hardboard to

which a 1-1/2 mil (.038 mm) thick melamine film has been laminated to

provide a serviceable, decorative finish. The material is supplied in 4

x 8 feet panels (1.2 x 2.4 m) and is applied to existing walls with an

adhesive. Pre-formed strips are used to cover vertical butted seams and

as a molding at the ceiling line. Baseboards are applied over the

paneling at the floor.

84
APPENDIX B: PACKAGE PLANS USED IN PHASE I

B.l Washington, Series I

Washington Series I Package Plans for Dwelling Units

Requiring Abatement of Interior Walls and Trim

PACKAGE

PLAN

WALLS

DRY AREA WET AREA DOORS

WINDOWS AND

WINDOW FRAMES

I -A Gypsum Wallboard Paint

Gypsum

Wal 1 board

Paint

Replace Replace

I-B Veneer

Plaster

Paint

Veneer

Plaster

Paint

Replace Replace

I-D Gypsjjm Jute Gypsum Jute Replace Replace

I-F Cementitious

Coating

Mel amine

Panel

Solvent Strip

Repaint

Solvent Strip

Repaint

I-G Plywood

Panel

Gypsum

Fiberglass

Dip Tank

Repaint

Solvent Strip

Repaint

B.2 Wash"ington, Series II

Washington Series II Package Plans for Dwelling Units

Requiring Abatement of Interior Trim Only

PACKAGE

PLAN WINDOWS DOORS BASEBOARD

ALL OTHER

TRIM

II-A Replace Replace Replace With

Wood

Replace With

Wood

II-B Replace Replace

II-C Solvent Strip

Repaint

Solvent Strip

Repaint

Replace With

Wood

II-D Solvent Strip

Repaint

Solvent Strip

Repaint

Solvent Strip

Repaint

Solvent Strip

Repaint

II-E Heat Gun

Repaint

Heat Gun

Repaint

Heat Gun

Repaint

Heat Gun

Repaint

II-F Solvent Strip

Repaint

Dip Tank

Repaint

Solvent Strip

Repaint

Solvent Strip

Repaint

85
B.3 Atlanta, Series I

Atlanta Series I Package Plans for Dwelling Units

Requiring Abatement of Interior Walls and Trim

PACKAGE

PLAN

WALLS

DRY AREA WET AREA

DOORS, WINDOWS

AND WINDOW FRAMES

ALL OTHER

TRIM

I -A Gypsum Wallboard, PaintGypsum

Wallboard,

Paint

Replace Replace

Wood

With

I-B Veneer

Plaster,

Paint

Veneer

Plaster,

Paint

Replace Replace

Wood

With

I-C Plaster with

Lath, Paint

Plaster

with

Lath,

Paint

Solvent

Repaint

Strip Solvent

Repaint

Strip

I-D Gypsum Jute Gypsum

Jute

Replace Solvent

Repaint

Stri p

I-E Filled Paint Filled

Paint

Solvent

Repaint

Strip Solvent

Repaint

Strip

I-F Cementitious

Coating

Mel amine

Panel

Solvent

Repaint

Stri p Solvent

Repaint

Stri p

I-H Gypsum Jute Vinyl

Coated

Fabric

Scrape

Repaint

Scrape

Repaint

B.4 Atlanta, Series II

Atlanta Series II Package Plans for Dwelling Units

Requiring Abatement of Trim Components Only

PACKAGE

PLAN

WINDOWS AND

WINDOW FRAMES

Replace

DOORS

ALL OTHER

TRIM

II-A Replace Replace

II-B Solvent Strip

Repaint

Solvent Strip

Repaint

Solvent Strip

Repaint

II-C Heat Gun

Repaint

Heat Gun

Repaint

Heat Gun

Repaint

II-D Solvent Strip

Repaint

Dip Tank

Repaint

Solvent Strip

Repaint

II-E* Solvent Strip

Repaint

Solvent Strip

Repaint

Continued on Next Page

86
Atlanta Series II Continued

PACKAGE WINDOWS AND ALL OTHER

PLAN WINDOW FRAMES DOORS TRIM

II-F* Replace Replace

II-G* Scrape Plywood

Repaint

*Denotes Exterior Surfaces

87
APPENDIX C: APPROXIMATE RANGES OVER WHICH COST

MODEL ESTIMATES ARE VALID

The tables presented in this Appendix are intended to serve as

guidelines as to what are or are not appropriate values for the detertninats of direct cost. Each table presents by abatement technique the

average values and the range of values for the four main determinants of

direct cost.

If it is desired to estimate the per unit direct costs of LBP

abatement using the cost models outlined in Chapter 4, the most reliable

estimates will result if the value of the determinant lies within the

range of values observed in Phase I. Prudence should be exercised

whenever a value outside this range is desired to be used since the

structure of the cost model may have been altered. Attention should

especially be given to the values used for the productivity of labor

since these values usually have a significant effect on per unit direct

cost. It is recommended that the average value for the productivity of

labor be used unless strong empirical evidence establishing a figure

which is different from that used in this study exists.

The tables presented in this Appendix give values for each determinant even if that determinant was not used in the cost model. This

additional information provides the cost estimacor with a better knowledge of just what type of figures went into the formulation of the cost

models.

88
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REFERENCES

Boone, T.H.; Berger, H.W.; Cramp, A. P.; Jackson, H.A., The Demonstration

of Experimental Lead Paint Hazard Abatement Methods in Washington ,

D.C. , National Bureau of Standards, Institutional Report 75-761,

June 1975.

Boone, T.H.; Berger, H.W.; Cramp, A. P.; Jackson, H.A., The Demonstration of Experimental Lead Paint Hazard Abatement Methods in Atlanta ,

Georgia , National Bureau of Standards, Institutional Report 75-974,

December 1975.

Brownlee, K.A., Statistical Theory and Methodology in Science and Engineering , John Wiley and Sons, Inc., 1960.

Dixon, W.J.; Massey, F.J., Introduction to Statistical Analysis , McGrawHill Book Company, 1957.

Draper, N.R.; Smith, H., Applied Regression Analysis , John Wiley and

Sons, Inc. , 1966.

Gilsinn, J.F., Estimates of the Nature and Extent of Lead Paint Poisoning in the United States , National Bureau of Standards, Technical Note 746, December 1972.

Hogben, D.; Peavy, S.T.; Varner, R.N., OMNITAB II User's Reference

Manual , National Bureau of Standards, Technical Note 552, October

1971.

"Lead-Based Paint Poisoning Prevention Act," Public Law 91-695, 91st

Congress, H.R. 19172, January 13, 1971, Amended, Public Law 93-151,

93rd Congress, November 9, 1973.

Scheffe, H., The Analysis of Variance , John Wiley and Sons, Inc., 1959.

Snedecor, G.W., Statistical Methods , Fifth Edition, Iowa State University

Press, 1956.

Waksman, D.; Ferguson, J.B.; Godette, M. ; Reichard, T. , Potential Systems for Lead Hazard Elimination: Evaluations and Recommendations

for Use , National Bureau of Standards, Technical Note 808, December

1973.

94
NBS-114A (REV. 7-73)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO.

NBS TN-9P.P,

2. Gov't Accession

No.

3. Recipient's Accession Nc

4. TITLE AND SUBTITLE 5. Publication De

Economic Analysis of Experimental Lead Paint Abatement

Methods: Phase I

September 1976

6. Performing Organization Code

7. AUTHOR(S)

Robert E. Chapman

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No.

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Office of Tolicy Development and Research

Department of Housing and Urban Development

Washington, D.C. 20410

13. Type of Report & Period Covered Interim FY 76

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

Library of Congress Catalog Card Number: 76-6OOO46.

16. ABSTRACT (A 200-word or less (actual summary o( most significant information. It document includes a significant

bibliography or literature survey, mention it here.) Public and private concern about the potential for lead poisoning in children due to the

ingestion of lead-based paint chips has resulted in a Federally sponsored program to

develop technologies by which lead-based paint may be eliminated from the nation's

housing. Through this program lead-based paint abatement techniques were tested in

field deleading operations conducted in Washington, D.C, and Atlanta, Ga. The program

also focused on the collection of data on the direct costs of labor, materials and

special equipment associated with these abatement techniques.

This report provides a statistical analysis by abatement technique and building com- ponent (i .e. , walls, doors, door frames, windows and frames, and miscellaneous trim) of

this direct cost data. Abatement techniques are then ranked according to their relative

costs. A cost model is developed for each category (ranking) which identifies the key

factors which affect direct cost and provides a framework whereby direct costs may be

estimated. Recommendations are made for further refinement of the model; a methodology

through which the optimal combination of lead-based paint abatement techniques can be

identified is also outlined.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons)

Abatement; building economics; building materials; economic analysis; housing; leadbased paint; lead poisoning.

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