Voluntary Product Standard PS 20-20

Revision 1

American Softwood Lumber Standard

October 2021

U.S. Department of Commerce

Gina M. Raimondo, Secretary

National Institute of Standards and Technology

James K. Olthoff, Performing the Non-Exclusive Functions and Duties of the Under Secretary of Commerce

for Standards and Technology & Director, National Institute of Standards and Technology
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VOLUNTARY PRODUCT STANDARDS

Development of Voluntary Product 

Standards

Voluntary Product Standards are developed 

under procedures published by the Department 

of Commerce in Title 15 Code of Federal Regulations Part 10, Procedures for the Development 

of Voluntary Product Standards. The purpose of 

these standards is to establish nationally recognized requirements for products and provide 

all concerned interests with a basis for common 

understanding of the characteristics of the 

products. The National Institute of Standards 

and Technology (NIST) administers the Voluntary Product Standards Program on a reimbursable basis.

Role of NIST

The role of NIST in the establishment of Voluntary Product Standards is to act as an unbiased 

coordinator in their development, provide editorial assistance in their preparation, supply such 

assistance and review as is required to assure 

their technical soundness, and to seek satisfactory resolution of valid points of disagreement. 

NIST also determines compliance with the criteria of the Department’s procedures, provides 

secretarial functions for each committee appointed under the procedures, and publishes 

the standards as public documents.

Producers, distributors, users, consumers, and 

other interested groups contribute to the establishment of Voluntary Product Standards by initiating and participating in their development, 

providing technical or other counsel as appropriate, promoting the use of and support for the 

standards, and assisting in keeping the standards current with respect to advancing technology and marketing practices.

Use of Voluntary Product Standards

The use of Voluntary Product Standards is voluntary. NIST has no regulatory power in the 

enforcement of their provisions: however, since 

the standards represent a consensus of all interested groups, their provisions are likely to

become established as trade customs. In addition, when a Voluntary Product Standard is 

made a part of a legal document, such as a sales 

contract or code, compliance with the standard 

is enforceable. 

The benefits derived from Voluntary Product 

Standards are in direct proportion to their general recognition and actual use. Producers and 

distributors whose products meet the requirements of a Voluntary Product Standard may refer to the standard in advertising and on labels 

to promote greater public understanding for 

confidence in their products. At times, purchasers may order products conforming to the requirements of a Voluntary Product Standard.

For copies of the Voluntary Product Standards 

procedures or for more information concerning 

the development and use of these standards, 

contact the Standards Coordination Office, National Institute of Standards and Technology, 

Gaithersburg, MD 20899-2100. 
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Voluntary Product Standard

PS 20-20 Revision 1

(Supersedes Voluntary Product Standard PS 20-20)

AMERICAN SOFTWOOD LUMBER STANDARD

PREFACE

The American Softwood Lumber Standard was developed by the American Lumber 

Standard Committee (ALSC) in accordance with the Procedures for the Development of Voluntary 

Product Standards of the U.S. Department of Commerce. The ALSC membership is appointed by 

the Secretary of Commerce to constitute a proper balance among producers, distributors, and 

consumers of softwood lumber. Pursuant to a U.S. District Court order, the ALSC and its Board 

of Review (Board) operate as independent bodies with defined functions with regard to establishing, maintaining, implementing and enforcing this Standard. Through a consensus process, the 

ALSC maintains the Standard and establishes policies and adopts other standards by which the 

Board certifies grading rules, approves design values, accredits agencies to grade and inspect under those rules and monitors the agencies' performance. The purpose of this standardization program for manufacturers, distributors, users and consumers is to provide for the correct grade 

mark labeling of lumber by mills using the service of an accredited agency. This Standard provides for the grading of structural lumber by both visual and mechanical means. A separate consensus body, the National Grading Rule Committee (NGRC) is established to develop and maintain nomenclature and descriptions of grades for dimension lumber that conform to this Standard.

This Standard applies to domestic production consumed in and exported from the United States, 

and for lumber imported into the United States. 
6

ABSTRACT

This Standard pertains to softwood lumber. It 

establishes standard sizes and requirements for 

development and coordination of the lumber 

grades of the various species, the assignment of 

design values when called for, and the preparation of grading rules applicable to each species. 

It provides for implementation of the Standard 

through an accreditation and certification program to assure uniform industry-wide marking 

and inspection.

It establishes principal trade classifications and 

lumber sizes for yard, structural, factory and 

shop use and provides for the classification, 

measurement, grade marking of rough and 

dressed sizes of lumber items. Terms and procedures are defined to provide a basis for the 

use of uniform methods in the grading, inspection, measurement and description of softwood 

lumber. It includes the organization and functions of the American Lumber Standard Committee, the Board of Review, and the National

Grading Rule Committee. Commercial names of 

the principal softwood species, definitions of 

terms used in describing standard grades of 

lumber and commonly used industry abbreviations are also provided.

The Standard was developed by the American 

Lumber Standard Committee in accordance 

with procedures of the U. S. Department of 

Commerce.

KEY WORDS

Accreditation; ALSC Board of Review; certification of grading rule; DOC PS 20-20; lumber inspection; lumber sizes; moisture content of 

lumber; National Grading Rule; softwood lumber standard
7

TABLE OF CONTENTS

PREFACE ................................................................................................................................. 5

1. SCOPE ................................................................................................................................. 9

2. TERMINOLOGY................................................................................................................ 10

3. CLASSIFICATION ............................................................................................................ 11

4. MEASUREMENT AND TALLY........................................................................................ 12

5. LUMBER SIZES................................................................................................................ 13

6. GRADING RULE REQUIREMENTS ............................................................................... 18

7. GRADE MARKING (GRADE STAMPING) ...................................................................... 21

8. INSPECTION AND REINSPECTION.............................................................................. 22

9. AMERICAN LUMBER STANDARD COMMITTEE......................................................... 24

10. BOARD OF REVIEW....................................................................................................... 26

11. NATIONAL GRADING RULE COMMITTEE................................................................ 29

12. REFERENCES................................................................................................................. 30

APPENDIX A COMMERCIAL NAMES OF THE PRINCIPAL SOFTWOOD SPECIES.... 31

APPENDIX B DEFINITIONS OF TERMS USED IN DESCRIBING

STANDARD GRADES OF LUMBER............................................................... 34

APPENDIX C LUMBER INDUSTRY ABBREVIATIONS .................................................. 44

APPENDIX D IMPLEMENTATION AND MAINTENANCE OF STANDARD .................. 47
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AMERICAN SOFTWOOD LUMBER STANDARD

Effective October 2021

[This Standard, which was initiated by the American Lumber Standard Committee, has been developed under the Procedures for the Development of Voluntary Product Standards of the U.S. Department of Commerce to supersede PS 20-20 Revision 1 “American Softwood Lumber Standard.”]

1. SCOPE

1.1 General

1.1.1 This Voluntary Product Standard establishes and maintains, through a consensus process and in the public interest, standard sizes 

(both in metric1 and conventional units) and general requirements for developing grades of softwood lumber. It is implemented through an internationally recognized accreditation and certification program, the purpose of which is to provide for uniform, industry-wide grade marking 

and inspection of softwood lumber.

1.1.2 This Standard also provides a basis for 

the coordination of the grades of the various species of softwood lumber, the assignment of design 

values to lumber when called for, and the preparation of grading rules applicable to each species. 

The provisions of this Standard apply to structural lumber manufactured from hardwood species or lumber manufactured from foreign species 

when the species is included in rules certified by 

the Board of Review. It is not intended to be used 

either as grading rules or as purchase specifications. Italicized notes in this Standard are nonmandatory.

1 Metric units are provided initially followed by conventional units.

1.1.3 This Standard establishes the principal 

trade classifications and sizes of softwood lumber 

for yard, structural, factory and shop use. It provides for the classification, measurement, grading and grade marking of rough and dressed sizes of various items of lumber including finish, 

boards, dimension and timbers. Terms and procedures are defined and discussed to provide a

basis for the use of uniform methods in the grading, inspection, measurement and description of 

softwood lumber.

Note: The provisions of this Standard do not apply to the myriad of products of remanufacture 

(for example: turned balusters, peeler cores, etc.) 

or manufactured components (for example: trusses, lattice panels, I-joists, etc.) that use “American 

Lumber Standard” (ALS) program lumber as a 

raw material.

1.1.4 This Standard applies to lumber that is 

to be identified as a manufactured product from 

a softwood log in a sawmill, or in a sawmill and

planing mill. Such lumber, when rough, shall 

show saw or other primary manufacturing marks 

in the wood on the four longitudinal surfaces of 

each piece for its over-all length and shall not 

have been further manufactured other than by 

crosscutting, ripping, resawing, joining by fingerjointing, face-gluing and/or edge-gluing, sur-
10

facing with or without end matching, and working.

1.1.5 In this Standard, lumber conforming to 

the basic minimum size and grade provisions 

herein is designated “American Lumber Standard” (ALS) program lumber only when graded 

under rules certified by the Board of Review 

(Board).

1.2 This Standard also includes the following:

(a) Organization and functions of the American Lumber Standard Committee (ALSC), 

the Board, and the National Grading Rule 

Committee (NGRC) 2;

(b) Commercial names of the principal softwood species (Appendix A);

(c) Definitions of terms used in describing 

standard grades of lumber (Appendix B);

(d) Commonly used lumber industry abbreviations (Appendix C); and

(e) Information on implementation, and 

maintenance of the Standard (Appendix 

D).

2. TERMINOLOGY

2.1 Accreditation--Procedure by which an 

authoritative body gives formal recognition that a 

body or person is competent to carry out specific 

tasks.

2.2 Board measure--The term used to indicate that a board foot is the unit of measurement 

of lumber. The number of board feet in a piece of 

lumber is obtained by multiplying the nominal 

thickness in inches or fraction of an inch by the 

nominal width in feet by the length in feet. For 

metric measurement, [see 2.5].

2 The American Lumber Standard Committee, Inc., its 

Board of Review, and its National Grading Rule Committee disclaim any liability for damages, including 

consequential damages, in connection with the use or 

performance in use of products produced.

2.3 Certification--Procedure by which a 

third party gives written assurance that a product, process or service conforms to specified requirements.

2.4 Characteristics--Distinguishing features which by their extent, location, and number 

determine the quality of a piece of lumber. The 

limiting characteristics of any grade of lumber described in certified grading rules shall be expressed within the terms of the definitions in Appendix B.

2.5 Cubic measurement--The term used to 

indicate that a cubic meter is the metric unit of 

measurement of lumber. The number of cubic meters in a piece of lumber is obtained by multiplying the dressed thickness in millimeters by the 

dressed width in millimeters by the length in meters and dividing the product by 1,000,000. [see 

Appendix B1]

2.6 Design values-- Strength and stiffness 

property values of structural lumber products 

published for design use. These values are determined for specific grades and species/species 

groups and reflect the fact that wood is an orthotropic material.

2.7 Dry lumber--Lumber of less than nominal 5-inch thickness which has been seasoned or 

dried to a maximum moisture content of 19 percent.

Note: Lumber of nominal 5-inch or greater thickness (timbers) is often manufactured and sold 

without drying.

When the maximum moisture content is specified 

for lumber of nominal 5-inch or greater thickness, it shall be in accordance with the provisions 

of the applicable lumber grading rules certified 

by the Board, which for some species defines dry 

lumber as having a maximum moisture content 

higher than 19 percent [see 6.2.6].
11

2.8 Grade marked (grade stamped)--

Lumber that displays the official grading mark of 

an agency that is made by rubber stamps, ink jet 

sprayers, tags and/or other methods when found 

acceptable by that agency. A grade mark is owned 

by the grading agency and is applied to lumber

that conforms to the requirements of a designated 

grading rule. Except for marks used in connection

with Certificates of Inspection or Reinspection, all 

grade marks shall indicate the following: 1) the 

mill number, name, or abbreviation; 2) the agency 

symbol; 3) the species or combination of species of 

the lumber; 4) whether the lumber was dry or 

green when manufactured (but, see 6.2.6); and 5) 

the appropriate grade. Where required by the 

grading rules, grade marks shall also denote rule 

paragraphs under which the lumber was graded 

or other similar information.

2.9 Grade– A minimum standard specifying 

the permitted characteristics of lumber, having 

regard to the end use for which the lumber is intended.

2.10 Grading agency-- An organization accredited by the Board that engages in the grading 

of lumber or that licenses and supervises facilities 

that employ graders to grade and/or to place grade 

marks upon lumber products.

2.11 Grading rules-- Requirements and 

specifications for the manufacture, inspection and 

grading of designated species of lumber. Lumber 

manufactured and graded according to the provisions of this Standard and the grading rules for 

the species in question shall be regarded as ALS 

program lumber.

2.12 Green lumber-- Lumber of less than 

nominal 5-inch thickness which has a moisture 

content in excess of 19 percent. For lumber of 

nominal 5-inch or greater thickness (timbers), 

green shall be defined in accordance with the provisions of the applicable lumber grading rules certified by the Board.

2.13 Heat treated (HT)-- Lumber or other 

wood products that have been heated in a chamber, with or without moisture content reduction, 

until it achieves a minimum core temperature of 

56 °

C for a minimum of 30 minutes.

2.14 Kiln dried (KD)-- Lumber that has 

been seasoned in a chamber to a predetermined 

moisture content by applying heat.

2.15 Lumber-- Lumber is defined as a manufactured product derived from a log through sawing or planing. [see 3.3]

2.16 Nominal size-- The label designation for 

lumber size categories that does not reflect the 

dressed size. The nominal size is greater than the 

dressed size i.e., a dry 2 by 4 is surfaced to 38.1

mm by 88.9 mm (1 1/2 by 3 1/2 inches) [see 3.4.4]. 

2.17 Species--The commercial names contained in Appendix A for lumber cut from the 

principal botanical species of softwood shall be 

used in the formulation of lumber grading rules 

and in the terms of purchase and sale of ALS 

program lumber.

2.18 Worked lumber (working)--Dressed 

lumber that has also been matched, shiplapped or 

patterned.

3. CLASSIFICATION

3.1 General—ALS program lumber shall be 

classified according to the use, extent-ofmanufacture and nominal size.

3.2 Use

3.2.1 Yard lumber-- Lumber of those grades, 

sizes, and patterns intended for ordinary construction and building purposes [see 6.3.1].

3.2.2 Structural lumber-- Lumber for use 

where design values are required [see 6.3.2].
12

3.2.3 Factory and shop lumber-- Lumber 

that is produced or selected for remanufacturing 

purposes and intended for non-structural applications [see 6.3.3].

3.3 Extent-of-manufacture

3.3.1 Rough lumber-- Lumber which has not 

been dressed (surfaced) but which has been

sawed, edged and trimmed at least to the extent 

of showing saw or other primary manufacturing 

marks in the wood on the four longitudinal surfaces of each piece for its over-all length. Lumber 

surfaced on one edge (S1E), two edges (S2E), one 

side (S1S), or two sides (S2S) is classified as rough 

lumber in the unsurfaced width or thickness.

3.3.1.1 Saw-sized lumber– Lumber uniformly 

sawn to the dressed size for surfaced lumber, and 

not planed on the faces, for uses requiring a 

rough texture. When saw sized lumber is grade 

marked it shall be labeled as such.

3.3.1.2 Sized lumber– Lumber uniformly 

manufactured to dressed surfaced sizes. Sized 

lumber may be rough, surfaced or partially surfaced on one or more faces. When sized lumber is 

grade marked it shall be labeled as such.

3.3.2 Dressed (surfaced) lumber-- Lumber 

that has been surfaced by a machine (to attain 

smoothness of surface and uniformity of size) on 

one side (S1S), two sides (S2S), one edge (S1E), 

two edges (S2E), or a combination of sides and 

edges (S1S1E, S1S2E, S2S1E, S4S). Lumber surfaced S1E, S2E, S1S, S2S, S1S1E, S1S2E, S2S1E, 

S4S is classified as dressed (surfaced) lumber in 

the surfaced width or thickness.

3.3.3 Worked lumber-- Dressed lumber that 

has also been matched, shiplapped or patterned.

3.3.3.1 Matched (tongue-and-grooved, centermatch) lumber-- Lumber worked with a 

tongue on one edge of each piece and a groove on 

the opposite edge to provide a close tongue-andgroove joint by fitting two pieces together; when 

end-matched, the tongue and groove are worked 

in the ends also.

3.3.3.2 Shiplapped lumber-- Lumber worked 

or rabbeted on both edges of each piece to provide 

a close-lapped joint by fitting two pieces together.

3.3.3.3 Patterned lumber-- Lumber shaped to 

a pattern or to a molded form, in addition to being 

dressed, matched, or shiplapped, or any combination of these workings.

3.4 Nominal size 

3.4.1 Boards-- Lumber of less than nominal 2-

inch thickness and of nominal 2-inch or greater

width. Lumber of less than nominal 2-inch thickness and of less than nominal 6-inch width is designated as strips or boards.

3.4.2 Dimension-- Lumber from nominal 2-

inch to, but not including, nominal 5-inch thickness, and of nominal 2-inch or greater width. Dimension is also designated as framing, joists, 

planks, rafters, or studs.

3.4.3 Timbers-- Lumber of nominal 5-inch or 

greater in least dimension. Timbers are also designated as beams, stringers, posts, caps, sills, 

girders, or purlins.

3.4.4 The dressed sizes of all lumber dimensions referenced in this Standard in terms of 

"nominal" sizes are set-out in Tables 1 through 4. 

The use of "nominal" sizes in the language of this 

Standard follows the practice of the industry. No

inferences shall be drawn that the "nominal" sizes 

are dressed sizes. [see 2.16]

4. MEASUREMENT AND TALLY

4.1 Tally, standard sizes-- Lumber shall be 

tallied board measure or cubic measure. Dressed 
13

sizes shall be used when lumber is measured by 

cubic measure.

Note: The invoices for dressed lumber of standard 

sizes should show the number of pieces of each 

nominal size and length as well as the actual 

thickness and width of such lumber.

4.2 Tally, nonstandard sizes-- Lumber finished to nonstandard sizes shall be tallied board 

measure as of either the rough or the nominal size

that was used in its manufacture. Cubic measure 

of lumber shall also be permitted. Dressed sizes 

shall be used when lumber is measured by cubic 

measure.

Note: The dressed thickness and width of such 

lumber should be shown on the invoice.

4.3 Board rule tally— In lumber specified 

to be measured with a board rule on dressed 

widths, pieces measuring to the even half foot are 

alternately counted as of the next higher and lower foot count; fractions below the half foot are 

dropped, and fractions above the half foot are 

counted as of the next higher foot.

4.4 Averages3--length, width-- The average length in feet of a shipment of lumber is computed by dividing the total length in feet by the 

total number of pieces in the shipment. The average width in inches of a shipment of lumber of 

nominal 1 inch or less thickness is computed by 

dividing the total board feet by the total length in 

feet and multiplying the results by 12; but if the

pieces are thicker than nominal 1 inch, the total 

board foot tally is divided first by the nominal 

thickness as expressed in inches and fractions of 

an inch.

5. LUMBER SIZES

5.1 Rough size-- The minimum rough 

thickness of dry or unseasoned lumber 1 or more 

inches in nominal thickness shall be not less than 

3.2 mm (1/8 inch) thicker than the corresponding 

3 This computation applies to conventional units.

minimum dressed thickness, except that up to 20 

percent of a shipment shall be not less than 2.4 

mm (3/32 inch) thicker than the corresponding 

minimum dressed thickness. The minimum rough 

widths shall not be less than 3.2 mm (1/8 inch) 

wider than the corresponding minimum dressed 

width.

5.2 Dressed sizes-- Dressed sizes of lumber 

shall equal or exceed the minimum sizes shown in 

Tables 1, 2, 3 and 4. Sizes in Tables 1, 2, 3 and 4 

pertain to those items as measured at time of 

manufacture. Lumber will change in dimension 

(shrink or expand) in response to its equilibrium 

moisture content [see 6.2.3.1 and 6.2.5.1]. [See also 5.3.1 covering length and 7.3 for grade marking 

nonstandard sizes.]

5.3 Lengths

5.3.1 Standard-- Standard lengths of lumber 

shall be in multiples of 0.3048 m (1 foot) or 0.6096 

m (2 feet) as specified in the certified grading 

rules.

5.3.2 Trimmed-- Unless otherwise stated in 

the contract of purchase, lumber shall be trimmed 

for the removal of spur and splintered ends, and if 

2 inches or less in nominal thickness (except lath), 

shall be double-end-trimmed to a length that is 

not less than the nominal length and that is not 

more than 76 mm (3 inches) in excess of nominal 

length. The overlength tolerance in nominal 2

inch dimension over 305 mm (12 inches) wide or 

over 6.1 m (20 feet) in length is 305 mm (12 inches).

Note: The marketing practice covering lengths of 

lumber should permit the buyer to obtain specified 

lengths or specified assortments of lengths.
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Table 1. Nominal and minimum-dressed dry sizes of finish, flooring, ceiling, partition, and 

stepping at 19 percent maximum-moisture content.

The thicknesses apply to all widths and all widths apply to all thicknesses except as modified. Sizes are 

given in millimeters and inches. Metric units are based on dressed size. See B1, Appendix B for rounding 

rule for metric units.

Item

Thicknesses Widths

Nominal 

Inch

Minimum Dressed Nominal

Inch

Minimum Dressed

mm inch mm inch

Finish

3/8

1/2

5/8

3/4

1

1-1/4

1-1/2

1-3/4

2

2-1/2

3

3-1/2

4

8

11

14

16

19

25

32

35

38

51

64

76

89

5/16

7/16

9/16

5/8

3/4

1

1-1/4

1-3/8

1-1/2

2

2-1/2

3

3-1/2

2

3

4

5

6

7

8

9

10

11

12

14

16

38

64

89

114

140

165

184

210

235

260

286

337

387

1-1/2

2-1/2

3-1/2

4-1/2

5-1/2

6-1/2

7-1/4

8-1/4

9-1/4

10-1/4

11-1/4

13-1/4

15-1/4

Flooring a

3/8

1/2

5/8

1

1-1/4

1-1/2

8

11

14

19

25

32

5/16

7/16

9/16

3/4

1

1-1/4

2

3

4

5

6

29

54

79

105

130

1-1/8

2-1/8

3-1/8

4-1/8

5-1/8

Ceiling a

3/8

1/2

5/8

3/4

8

11

14

17

5/16

7/16

9/16

11/16

3

4

5

6

54

79

105

130

2-1/8

3-1/8

4-1/8

5-1/8

Partition a 1 18 23/32

3

4

5

6

54

79

105

130

2-1/8

3-1/8

4-1/8

5-1/8

Stepping 1

1-1/4

1-1/2

2

19

25

32

38

3/4

1

1-1/4

1-1/2

8

10

12

184

235

286

7-1/4

9-1/4

11-1/4

a In tongued-and-grooved flooring and in tongued-and-grooved and shiplapped ceiling of 8 mm (5/16 inch), 11 mm (7/16 

inch), and 14 mm (9/16 inch) dressed thicknesses, the tongue or lap shall be 5 mm (3/16 inch) wide, with the over-all 

widths 5 mm (3/16 inch) wider than the face widths shown in the above table. In all other worked lumber shown in 

this table of dressed thicknesses of 16 mm (5/8 inch) to 32 mm (1-1/4 inches), the tongue shall be 6 mm (1/4 inch) 

wide or wider in tongued-and-grooved lumber, and the lap shall be 10 mm (3/8 inch) wide or wider in shiplapped 

lumber, and the over-all widths shall be not less than the dressed face widths shown in the above table plus the 

width of the tongue or lap.
15

Table 2. Nominal and minimum-dressed dry sizes of siding at 19 percent maximummoisture content.

The thicknesses apply to all widths and all widths apply to all thicknesses. Sizes are given in millimeters 

and inches. Metric units are based on dressed size. See B1, Appendix B for rounding rule for metric units.

Item

Thicknesses Widths

Nominal 

Inch

Minimum Dressed Nominal

Inch

Minimum Dressed

mm inch mm inch

Plain Bevel

1/2

9/16

5/8

3/4

1

11 butt, 5 tip

12 butt, 5 tip

14 butt, 5 tip

17 butt, 5 tip

19 butt, 5 tip

7/16 butt, 3/16 tip

15/32 butt, 3/16 tip

9/16 butt, 3/16 tip

11/16 butt, 3/16 tip

3/4 butt, 3/16 tip

4

5

6

8

10

12

89

114

140

184

235

286

3-1/2

4-1/2

5-1/2

7-1/4

9-1/4

11-1/4

Rabbeted 

Bevel

1/2

3/4

11 butt, 5 tip

17 butt, 7 tip

7/16 butt, 3/16 tip

11/16 butt, 9/32 tip

4

6

8

10

12

89

140

184

235

286

3-1/2

5-1/2

7-1/4

9-1/4

11-1/4

Bungalow 3/4 17 butt, 5 tip 11/16 butt, 3/16 tip

6

8

10

12

140

184

235

286

5-1/2

7-1/4

9-1/4

11-1/4

Shiplap (10 

mm (3/8 in.) 

lap)b

5/8

1

14

18 a

9/16

23/32 a

4

5

6

8

10

12

76

102

127

171

222

273

3

4

5

6-3/4

8-3/4

10-3/4

Shiplap ( 13 

mm (1/2 in.) 

lap)b

5/8

1

2

14

18 a

38

9/16

23/32 a

1-1/2

4

5

6

8

10

12

73

98

124

168

219

270

2-7/8

3-7/8

4-7/8

6-5/8

8-5/8

10-5/8

Dressed and 

Matched 

(Tongue and 

Grooved, 6 

mm (1/4 in.) 

tongue)b

5/8

1

14

18 a

9/16

23/32 a

4

5

6

8

10

12

79

105

130

175

225

276

3-1/8

4-1/8

5-1/8

6-7/8

8-7/8

10-7/8

Dressed and 

Matched 

(Tongue and 

Grooved, 10 

mm (3/8 in.) 

tongue)b

1 18 a 23/32 a

4

6

8

10

12

76

127

171

222

273

3

5

6-3/4

8-3/4

10-3/4

a Minimum dressed thickness for 1-inch nominal redwood and western red cedar shiplap and tongue and groove siding 

patterns is 17 mm (11/16 inch). b In siding lumber less than nominal 2-inch thickness, the tongue shall be 6 mm (1/4 inch) or 10 mm (3/8 inch) wide in 

tongued and grooved lumber and the lap shall be 10 mm (3/8 inch) or 13 mm (1/2 inch) wide in shiplapped lumber

with the over-all widths 6 mm (1/4 inch), 10 mm (3/8 inch) and 13 mm (1/2 inch) wider, respectively, than the face 

widths shown in the above table.
16

Table 3. Nominal and minimum-dressed sizes of boards, dimension, and timbers.

The thicknesses apply to all widths and all widths apply to all thicknesses. Sizes are given in millimeters and inches. 

Metric units are based on dressed size. See B1, Appendix B for rounding rule for metric units.

Item

Thicknesses Widths

Nominal

Inch

Minimum Dressed Nominal

Inch

Minimum Dressed

Dry a Green a,b Dry a Green a,b

mm inch mm Inch mm inch mm inch

Boards 

3/8

1/2

5/8

3/4

1

1-1/4

1-1/2

8

11

14

16

19

25

32

5/16

7/16

9/16

5/8

3/4

1

1-1/4

9

12

15

17

20

26

33

11/32

15/32

19/32

11/16

25/32

1-1/32

1-9/32

2

3

4

5

6

7

8

9

10

11

12

14

16

38

64

89

114

140

165

184

210

235

260

286

337

387

1-1/2

2-1/2

3-1/2

4-1/2

5-1/2

6-1/2

7-1/4

8-1/4

9-1/4

10-1/4

11-1/4

13-1/4

15-1/4

40

65

90

117

143

168

190

216

241

267

292

343

394

1-9/16

2-9/16

3-9/16

4-5/8

5-5/8

6-5/8

7-1/2

8-1/2

9-1/2

10-1/2

11-1/2

13-1/2

15-1/2

Dimension

2

2-1/2

3

3-1/2

4

4-1/2

38

51

64

76

89

102

1-1/2

2

2-1/2

3

3-1/2

4

40

52

65

78

90

103

1-9/16

2-1/16

2-9/16

3-1/16

3-9/16

4-1/16

2

2 1/2

3

3 1/2

4

4 1/2

5

6

8

10

12

14

16

38

51

64

76

89

102

114

140

184

235

286

337

387

1-1/2

2

2-1/2

3

3-1/2

4

4-1/2

5-1/2

7-1/4

9-1/4

11-1/4

13-1/4

15-1/4

40

52

65

78

90

103

117

143

190

241

292

343

394

1-9/16

2-1/16

2-9/16

3-1/16

3-9/16

4-1/16

4-5/8

5-5/8

7-1/2

9-1/2

11-1/2

13-1/2

15-1/2

Timbers

5 & 6 

thick 13 off 1/2 off 13 off 1/2 off 5 & 6 

wide 13 off 1/2 off 13 off 1/2 off

7-15 thick 19 off 3/4 off 13 off 1/2 off 7-15 wide 19 off 3/4 off 13 off 1/2 off

>=16 

thick 25 off 1 off 13 off 1/2 off >= 16 

wide 25 off 1 off 13 off 1/2 off

a See 2.7 and 2.11 for the definitions of dry and green lumber.

b except for minimum dressed green sizes for Redwood, Western Red Cedar, and Northern White Cedar [see section 6.2.5].
17

Table 4. Nominal and minimum-dressed sizes of worked lumber.

The thicknesses apply to all widths and all widths apply to all thicknesses. Sizes are given in millimeters and inches. 

Metric units are based on dressed size. See B1, Appendix B for rounding rule for metric units.

Item

Thicknesses Widths

Nominal

Inch

Minimum Dressed Nominal 

Inch

Minimum Dressed

Drya Greena,b Drya Greena,b

mm inch mm inch mm inch mm inch

Shiplap,

10 mm (3/8 inch)

lapb

1 19d 3/4d 20 25/32

4

6

8

10

12

14

16

79

130

175

225

276

327

378

3-1/8

5-1/8

6-7/8

8-7/8

10-7/8

12-7/8

14-7/8

81

133

181

232

283

333

384

3-3/16

5-1/4

7-1/8

9-1/8

11-1/8

13-1/8

15-1/8

Shiplap,

13 mm (1/2 inch) 

lap c,d

1

2

2-1/2

3

3-1/2

4

4-1/2

19d

38

51

64

76

89

102

3/4d

1-1/2

2

2-1/2

3

3-1/2

4

20

40

52

65

78

90

103

25/32

1-9/16

2-1/16

2-9/16

3-1/16

3-9/16

4-1/16

4

6

8

10

12

14

16

76

127

171

222

273

324

375

3

5

6-3/4

8-3/4

10-3/4

12-3/4

14-3/4

78

130

178

229

279

330

381

3-1/16

5-1/8

7

9

11

13

15

Centermatch

(Tongue & 

Groove),

6 mm (1/4 inch) 

tonguec

1

1-1/4

1-1/2

19d

25

32

3/4e

1

1-1/4

20

26

33

25/32

1-1/32

1-9/32

4

5

6

8

10

12

79

105

130

175

225

276

3-1/8

4-1/8

5-1/8

6-7/8

8-7/8

10-7/8

81

108

133

181

232

283

3-3/16

4-1/4

5-1/4

7-1/8

9-1/8

11-1/8

Centermatch

(Tongue & 

Groove),

10 mm (3/8 inch) 

tongue d

2

2-1/2

3

3-1/2

4

4-1/2

38

51

64

76

89

102

1-1/2

2

2-1/2

3

3-1/2

4

40

52

65

78

90

103

1-9/16

2-1/16

2-9/16

3-1/16

3-9/16

4-1/16

4

6

8

10

12

76

127

171

222

273

3

5

6-3/4

8-3/4

10-3/4

78

130

178

229

279

3-1/16

5-1/8

7

9

11

Grooved-forSplines

2-1/2

3

3-1/2

4

4-1/2

51

64

76

89

102

2

2-1/2

3

3-1/2

4

52

65

78

90

103

2-1/16

2-9/16

3-1/16

3-9/16

4-1/16

4

6

8

10

12

89

140

184

235

286

3-1/2

5-1/2

7-1/4

9-1/4

11-1/4

90

143

190

241

292

3-9/16

5-5/8

7-1/2

9-1/2

11-1/2

a See 2.7 and 2.11 for the definitions of dry and green lumber. b except for minimum dressed green sizes for Redwood, Western Red Cedar, and Northern White Cedar [see section 6.2.5].

c In worked lumber less than nominal 2-inch thickness, the tongue shall be 6 mm (1/4 inch) wide in tongued and grooved lumber and 

the lap shall be 10 mm (3/8 inch) or 13 mm (1/2 inch) wide in shiplapped lumber, with the over-all widths 6 mm (1/4 inch), 10 

mm (3/8 inch) and 13 mm (1/2 inch) wider, respectively, than the face widths shown in the above table.

dIn worked lumber of nominal 2-inch and greater thickness, the tongue shall be 10 mm (3/8 inch) wide in tongued-and-grooved lumber and the lap shall be 13 mm (1/2 inch) wide in shiplapped lumber, with the over-all widths 10 mm (3/8 inch) and 13 mm (1/2 

inch) wider, respectively, than the face widths shown in the above table. Double tongued-and-grooved decking shall be manufactured with a 10 mm (3/8 inch) or 8 mm (5/16 inch) wide tongue. 

e Alternate minimum dressed dry thickness for 1-inch nominal center-match and shiplap is 18 mm (23/32 inch).
18

6. GRADING RULE REQUIREMENTS

6.1 General concepts

6.1.1 Grading parameters-- To the extent to 

which differences in the characteristics of species, 

in the quality of logs, in conditions of manufacture 

and in the uses to which the product is put will 

permit, the basic provisions for the grading of

lumber shall be uniform. The grading of lumber 

cannot be considered an exact science because it is 

based on either a visual inspection of each piece 

and the judgment of the grader or on the results 

of a method of mechanically determining the 

strength characteristics of structural lumber [see 

6.3.2.2]. Grading rule provisions shall be sufficiently explicit to establish 5 percent below grade 

as an allowable variation between qualified graders. If any grading rules indicate that a grade 

qualifies under two use classifications, the grade 

provisions shall satisfy the requirements for both 

classifications.

6.1.2 Minimum grade requirements-- The 

method of determining the extent and limitations 

of the characteristics permitted in the poorest 

pieces admissible in each grade of lumber shall be 

stated in a certified rule, except in the lowest 

grade of each classification. Since lumber grades 

are broad manufacturing categories, grades overlap and pieces are selected from a grade to comprise another grade outside of that grade category. A specific shipment shall not be made up of only pieces containing characteristics of the maximum number or size permitted in the grade.

6.1.3 Grade characteristics-- Characteristics permitted and limitations for rough lumber 

shall be the same as those prescribed in grading 

rules for dressed lumber of the same grade and, in 

addition, such others as will disappear in standard dressing shall be allowed. If characteristics 

other than those described in certified grading 

rules are encountered, they shall be evaluated in 

relation to the characteristics permitted or limitations prescribed for the grade under consideration 

and shall be allowed if regarded as equivalent or 

less damaging in effect on the strength, appearance, or other utility value of the piece. In all 

grades, the size of allowable characteristics shall 

not exceed that specified in the respective grading 

rules.

Note: In many grades, the size of permitted characteristics varies in proportion to the size of a face 

or the area of a cross section of the piece. 

6.1.4 Special provisions-- When heartwood, 

sapwood, grain classifications, and other optional 

provisions are specified, and the lumber conforms 

to the requirements of such special provisions as 

well as to the regular grade designated, it shall be

regarded as of standard quality.

6.1.5 Mixed grades-- Mixed grades other 

than the two highest established grades for each 

grading rule category shall not be included in certified grading rules.

6.1.6 Nonstandard grades-- When nonstandard grades, sizes, or patterns are specified, 

or when particular provisions of a standard grade 

are waived or changed, inspection shall be made 

accordingly, but all of the other provisions of the 

certified grading rules shall apply.

6.2 Seasoning provisions

6.2.1 General— The grading rules shall include provisions regulating lumber seasoning and 

moisture content. The provisions shall be developed by each geographical region for each species 

based on its own conditions and the requirements 

of the users of its products subject to the other 

provisions of Section 6. Provisions shall be expressed in terms of maximum moisture content 

allowed in each piece of lumber and determined in 

accordance with ASTM D 4444 Standard Test 

Method for Laboratory Standardization and Calibration of Hand-Held Moisture Meters and ASTM 

D 7438 Standard Practice for Field Calibration 

and Application of Hand-Held Moisture Meters as 
19

appropriate. The restrictions on the moisture content of seasoned lumber shall apply at the time of 

shipment, at the time of dressing (if dressed lumber is involved), and at the time of any reinspection (if moisture content is involved in the reinspection), as provided in the applicable grading 

rules. Any piece exceeding the allowable moisture 

content of the applicable grade provisions shall be 

considered out of compliance.

6.2.2 Grading rules-- The grading rules for 

each species or region shall include clear definitions for dry lumber under nominal 5-inch thickness [see 2.7]. The definitions shall be based on a 

maximum moisture content of 19 percent or less. 

The choice to grade and grade mark any item as 

green ALS program lumber or dry ALS program 

lumber shall be determined by each rules writing 

agency in accordance with its own conditions [see

2.7, 2.11, and 2.12].

6.2.3 Dry size requirements-- The grading 

rules shall require lumber under nominal 5-inch 

thickness sold as dry to be 19 percent or less in 

moisture content at the time of dressing, and to be 

not less than ALS minimum dry dressed thickness and width at 19 percent moisture content, or 

at such lower maximum-moisture content as may 

be applicable to the lumber at the time of dressing. The minimum-dressed dry sizes are shown in 

tables 1, 2, 3 and 4.

6.2.3.1 Shrinkage or expansion from dry 

size– Shrinkage or expansion that occurs after 

dressing to standard dry size shall be recognized 

through the allowance of a tolerance below or 

above minimum standard dry sizes on a basis of 

1 percent shrinkage or expansion for each four 

percentage points of moisture content change or 

0.7 percent shrinkage or expansion for each four 

percentage points of moisture content change for 

Redwood, Western Red Cedar, and Northern 

White Cedar. The shrinkage or expansion percentages are average values. Shrinkage or expansion of individual pieces may vary.4 Shrinkage allowances are determined assuming maximum allowable moisture content at the time of 

surfacing. Expansion allowances are determined 

assuming a typical equilibrium moisture content 

or other suitable reference moisture content.

6.2.4 Size differentials-- When the grading 

rules in any region permit lumber less than nominal 5-inch thickness to be dressed green, the rules 

shall require that the lumber be dressed to sizes 

specifically stated according to both thickness and 

width, as set forth in tables 3 and 4.

6.2.5 Green size requirements-- The minimum dressed green sizes specifically stated in the 

rules shall be not less than the green sizes5 shown 

in tables 3 and 4, except for Redwood, Western 

Red Cedar, and Northern White Cedar. For these 

three species, the following minimum dressed 

green thicknesses shall apply: 17 mm (21/32 inch) 

for corresponding nominal 3/4 inch dry, 20 mm 

(25/32 inch) for nominal 1-inch, 40 mm (1-9/16 

inch) for nominal 2-inch, 52 mm (2-1/16 inch) for 

nominal 2-1/2 inch, 65 mm (2-9/16 inch) for nominal 3-inch, 78 mm (3-1/16 inch) for nominal 3-1/2 

inch, 90 mm (3-9/16 inch) for nominal 4-inch, and 

103 mm (4-1/16 inch) for nominal 4-1/2 inch. The 

following minimum green dressed widths shall

apply: 65 mm (2-9/16 inch) and 90 mm (3-9/16 

inch) for nominal 3-inch and 4-inch, 116 mm (4-

9/16 inch), 141 mm (5-9/16 inch), and 167 mm (6-

9/16 inch) for nominal 5-inch, 6-inch, and 7-inch, 

4 The range of shrinkage of individual pieces from experimental observation is from 2% to 7%. Variables that affect measurement and shrinkage of lumber are: density, 

species, grain orientation and allowable grade characteristics. See Forest Products Laboratory Research 

Reports 15 and 30. 5 The minimum green sizes are based on shrinkage factors 

of 2.35 percent in thickness and 2.80 percent in width 

from the fiber saturation point to a 19 percent maximum moisture content with recognition given to manufacturing practices and the differences in shrinkage 

characteristics between species of lumber or species 

groups of lumber.
20

187 mm (7-3/8 inch), 238 mm (9-3/8 inch), 289 mm 

(11-3/8 inch) for nominal 8-inch, 10-inch, and 12-

inch, 341 mm (13-7/16 inch) and 392 mm (15-7/16 

inch) for nominal 14-inch and 16-inch.

6.2.5.1 Shrinkage or expansion from green 

size– Shrinkage that occurs after dressing to 

standard green size shall be recognized through 

the allowance of a tolerance below minimum 

standard green sizes on a basis of 1 percent 

shrinkage for each four percentage points of 

moisture content below 30 percent or 0.7 percent 

shrinkage for each four percentage points of 

moisture content below 30 percent for Redwood, 

Western Red Cedar, and Northern White Cedar. 

Expansion allowances are determined assuming 

a typical equilibrium moisture content or other 

suitable reference moisture content. The shrinkage or expansion percentages are average values. 

Shrinkage or expansion of individual pieces may 

vary.6

6.2.6 Grade marking (grade stamping)--

Grading rules that provide for grade marking of 

lumber less than nominal 5-inch thickness shall 

contain a provision for standardized marking so 

as to indicate whether the lumber was green or 

dry at time of dressing. The standardized mark

shall be S-GRN if surfaced green, S-DRY if surfaced dry, or KD if kiln dried to a maximum moisture content of 19 percent at time of surfacing. 

Moisture-content limits of less than 19 percent 

maximum moisture-content for dry or kiln dried 

shall only be specified if included in rules certified 

by the Board. For lumber of nominal 5-inch or 

greater thickness, other moisture-content limits 

shall be specified only if included in rules certified

by the Board.

6 The range of shrinkage of individual pieces from experimental observation is from 2% to 7%. Variables that affect measurement and shrinkage of lumber are: density, 

species, grain orientation and allowable grade characteristics. See Forest Products Laboratory Research Reports 15 and 30.

6.3 Use classification provisions for visual grading

6.3.1 Yard lumber

6.3.1.1 Grade classifications-- The grading of 

surfaced yard lumber is based upon the uses for 

which the particular grade is designed and is applied to each kind with reference to its size and 

length when graded without consideration to further manufacture. On the basis of quality, the 

basic grade classifications of yard lumber shall be 

as follows:

(a) Select: Lumber for natural and paint finishes.

(b) Common: Lumber for general construction and utility purposes.

6.3.1.2 Yard lumber sizes-- The dressed thicknesses and widths of yard lumber as specified in 

3.4, 5.1 and 5.2 shall be considered as minimum 

standards for the corresponding nominal sizes as 

shown.

Note: Lumber of standard size, rough or dressed,

may be described by its nominal dimension 

providing dressed sizes are shown on invoices and 

other documents.

6.3.1.3 Bundled lumber-- Each length of bundled lumber, except end-matched lumber, beveled 

siding, and bungalow siding shall be bundled separately unless otherwise specified.

6.3.1.4 Finish and boards-- In shipments of 

rough finish/selects and boards, pieces 13 mm (1/2 

inch) or greater than the nominal inch-unit thickness, such as are produced by uneven sawing, 

shall, at the option of the buyer, be rejected or be 

accepted as of the next lower grade.

6.3.1.5 Grading faces-- Yard lumber other 

than timbers and dimension [see 6.3.2.3] shall be 

graded from the face or best side only unless otherwise specified.
21

6.3.1.6 Fencing – Sawn boards used in the 

construction of fences may be square-top, dogeared, square-edge or tongue and groove. The 

tolerance in sawing of such boards shall not exceed 1.6 mm (1/16 inch) over or under the invoice 

thickness.

6.3.2 Structural lumber

6.3.2.1 Development of design values--

Design values contained in grading rules shall be 

developed in accordance with appropriate ASTM 

standards and other technically sound criteria. 

The National Institute of Standards and Technology, with the advice and counsel of the U.S. Forest 

Products Laboratory, shall be the final authority 

as to the appropriateness of such standards or criteria. The Board shall seek the assistance of the 

U.S. Forest Products Laboratory in reviewing design values set forth in grading rules and, in the 

case of each set of grading rules submitted for certification, the Board shall obtain a report from the 

Laboratory evaluating whether the procedures 

used in developing the claimed values are in accordance with the standards and criteria described herein. Rules-writing agencies shall make 

available upon request an explanation of the 

means by which the claimed values were derived. 

When more than one rules-writing agency has responsibility for writing grading rules for a given 

species, a group of species, or a geographical subdivision of a species or of a group of species, a 

common set of strength and stiffness values shall 

be used by the agencies involved for that species, 

subdivision, or group of species in the interest of 

uniformity and standardization.

6.3.2.2 Grading--mechanical--The grading of 

structural lumber by mechanical means is recognized as an acceptable method of grading. When 

graded by mechanical means all such grading 

equipment and methods shall be subject to approval and certification by the Board.

6.3.2.3 Grading faces--Timbers and dimension 

shall be graded from all four faces.

6.3.3 Factory and shop lumber

6.3.3.1 Grade classification - The grade classifications of factory and shop lumber shall be those 

promulgated by the agencies which formulate and 

publish grading rules and which have been certified by the Board.

6.3.3.2 Grade characteristics--Factory and 

shop lumber shall be graded with reference to its 

use for doors and sashes, or on the basis of characteristics affecting its use for general cutup purposes, or on the basis of size of cutting. Its grade 

shall be determined by the percentage of the area 

of each board or plank available in cuttings of 

specified or of given minimum size and qualities 

and shall be determined from the poor face based 

on the quality of both sides of each cutting.

6.3.3.3 Grade sizes-- The ALS program grade 

sizes for factory and shop lumber shall be those 

promulgated by the agencies which formulate and 

publish grading rules and which have been certified by the Board.

6.3.3.4 Warped lumber--The cuttings in 

warped lumber shall be so laid out as to surface 

two sides to standard thickness and have straight 

edges parallel to the edges of the board or plank.

7. GRADE MARKING (GRADE STAMPING)

7.1 Agency procedures--Each accredited 

agency shall submit procedures with respect to 

grade marking to the Board for approval.

7.2 Agency symbol--Each accredited agency shall maintain a bona fide supervisory inspection service under which each mill authorized to 

use the registered symbol of the accredited agency7 in conjunction with the grade mark will be in7 Facsimiles of the grade marks of the grading and inspection agencies that are accredited by the Board of the 

ALSC, Incorporated, are available on the web at 
22

spected regularly as to grading efficiency and conformity to all the agency established rules for 

grade marking.

7.3 The Grade mark (grade stamp)--

When ALS program lumber is grade marked, the 

grade marking shall be subject to the following 

provisions:

7.3.1 The grade mark shall signify that the 

lumber conforms to the size, grade and seasoning 

provisions of the rules under which it is graded. 

When green lumber of less than nominal 5-inch 

thickness is graded and grade marked under the 

applicable grading rules [see also 6.2.6], it shall 

comply with the green size requirements of such 

rules. If lumber is dressed to a size below the minimum size requirements shown in Tables 1-4 or 

below the minimum sizes set forth in the applicable grading rules, the mark shall show that size, 

and if less than of nominal 5-inch thickness, shall 

state whether the lumber was dry or green when 

dressed.

7.3.2 A distinguishable mark or insignia, registered and symbolizing grading supervision by an 

accredited agency, shall be used in conjunction 

with the grade mark for each agency. Facsimiles 

of the grade marks of the grading and inspection 

agencies that are accredited shall be available to

specifiers, purchasers and consumers.8

7.3.3 All pieces and/or bundles of a given grade 

shall be grade marked. Bundled lumber is defined as a small number of boards or strips 

bound by some method, such as shrink wrap, 

string or similar binding, so as to form a small 

package.

www.alsc.org or from the ALSC, Incorporated, P.O. Box 

210, Germantown, MD 20875-0210. Telephone (301) 

972-1700, Fax (301) 540-8004.

8 Ibid.

7.3.3.1 Except for bundled lumber, the mixing of 

grade marked and non-grade marked lumber in 

the same package shall not be permitted. 

7.3.4 Mixed grades, other than the two highest 

recognized grades for each grading rule category, 

shall not be grade marked with a combination 

grade designation. 

7.3.5 The grade mark for lumber shall include 

an identification or designation of the commercial 

name of the species [see Appendix A] from which 

the lumber was produced. The identification of 

species shall not be required when the agency 

symbol also indicates the species from which the 

lumber was produced. Where grading rules contain provisions for the grouping of species, each 

individual species included in a group shall be 

identified in the rules, and the grade mark shall 

include the designation assigned to the group.

7.3.6 These provisions are not intended to preclude the inclusion of additional regulations by an 

agency regarding the use of its grade mark provided the basic provisions of this section are observed. 

7.3.7 Remanufacture (ripping, resawing or 

surfacing) of graded or grade marked lumber negates the grade or grade mark and the design values of the original product and the original grade 

mark shall be removed, by any appropriate 

means.

7.3.7.1 When grade marked dimension lumber is 

resawn or remanufactured in such a way as to potentially alter the grade indicated by the grade 

mark, the original grade mark shall be obliterated.

8. INSPECTION AND REINSPECTION

8.1 Inspection

8.1.1 Agency certification and supervision--When ALS program lumber is grade 
23

marked, the grade marking shall be under the direction, including regular grading supervision at 

mills, of an agency accredited by the Board as being competent and having adequate facilities for 

such supervision.

8.1.2 Delegation of grading authority--

Permission to grade mark shall be delegated only 

by an agency accredited by the Board to operate a 

mill supervisory service to those mills which have 

demonstrated and proven their ability to conform 

to and are currently in conformance with the 

grading rules for the species and grades which 

they manufacture. The mill shall also agree to 

maintain the established standards of size and 

grade and to submit its lumber to inspection by 

the supervisory agency both at the mill and upon

complaint at destination.

8.1.3 Payment--certificate costs-- When an 

accredited agency issues a certificate on a shipment, the party requesting the certificate shall 

pay for the cost thereof.

8.1.4 Service-- Inspection service shall be required for the inspection of grades not described 

in the rules only when written detailed specifications accompany the request for such inspection. 

For the inspection of standard grades in nonstandard sizes, inspection service shall be required based on 6.1.6 unless otherwise prescribed 

in the contract of purchase and sale.

8.2 Reinspection

8.2.1 General-- Subject to freedom of agreement between buyer and seller as to the settlement of complaints, the purchase, sale, or shipment of ALS program grades of lumber shall be 

construed as involving agreement to submit lumber to reinspection by an accredited inspection 

agency under published rules by which the lumber was graded [see 8.2.4]. Grading rules shall include provisions for reinspection in case of complaint, and reinspection shall be available to anyone at reasonable cost.

8.2.2 Complaints-- Grade complaints on lumber shall be recognized only when the lumber is in 

the form in which it was shipped. Any subsequent 

change in manufacture, working, or through kilndrying shall relieve the seller of responsibility for 

any grade complaints.

8.2.3 Buyer's responsibilities-- In case of a 

complaint, the buyer shall accept that portion of 

the shipment that is of the grade, size, and moisture content specified and shall hold intact that

portion which is disputed for inspection or reinspection. Any action on the part of the buyer in 

accepting and using such portion of the shipment 

that is of the grade, size, and moisture content 

specified shall not be construed as the acceptance 

of the entire shipment. The buyer shall hold the 

disputed lumber intact, properly protected, for not 

more than 30 days after the date of the request for 

inspection or reinspection. The buyer shall file a 

complaint with the seller within the time specified 

in 8.2.6 and 8.2.7. The buyer shall pay in accordance with the terms of the sale for that portion accepted, but acceptance of a part of a shipment 

does not prejudice the buyer’s just claims that any 

unused lumber does not meet the specifications of 

the grade, size, or moisture content.

8.2.4 Seller's responsibilities-- Upon receipt 

of a complaint from the purchaser, the seller shall 

immediately request the agency under whose 

rules shipment has been made, or such other 

agency that was agreed upon, to provide inspection, reinspection or retally as required according 

to the grading rules in effect at the time of execution of the contract.

8.2.5 Cost and assistance-- The expense of 

such inspection, reinspection, or retally shall be 

borne in accordance with the inspection provisions 

of the applicable grading rules, but the person 

calling for the reinspection shall be responsible to 

the agency for the costs thereof. The purchaser 

shall lend all reasonable assistance to facilitate

the inspection, reinspection or retally.
24

8.2.6 Tally, grade, and size complaints-- In 

case of a complaint involving tally, the entire item 

shall be held intact for retally. In case of a complaint regarding grade or size, but not involving 

tally, the buyer shall hold intact that portion of 

the item that is of the grade or size which is in 

dispute for inspection and shall file complaint 

with the seller within 10 days of date of receipt of 

the shipment.

8.2.7 Moisture content complaints-- In 

case of a complaint involving moisture content, 

the buyer shall inform the seller of the complaint 

within 72 hours after the lumber is unloaded. In 

such cases, the seller shall answer such complaint 

within 72 hours from receipt of complaint. A reinspection involving a complaint on moisture content shall be made in accordance with the provisions of the applicable grading rules. Each piece 

shall be tested for moisture content, and separation shall be made of all pieces conforming to the 

maximum allowable moisture content from any 

portion exceeding such maximum.

8.2.8 Reinspection results-- Each item of a 

shipment shall be considered as of the grade invoiced if, upon reinspection under the grading 

rules under which the lumber was graded and 

sold, 95 percent or more thereof is found to be of 

said grade or better. When degrades in grade or 

moisture content or both are in excess of 5 percent 

of the board footage of each item, or when they are 

more than one grade lower than the grade invoice, 

such degrades shall be kept separate and shall be 

the property of the seller unless otherwise agreed. 

These provisions shall not apply in the case of 

specially worked lumber.

9. AMERICAN LUMBER STANDARD 

COMMITTEE

9.1 Functions of ALSC-- The functions of 

the ALSC shall be:

9.1.1 To act as the Standing Committee for the 

purpose of considering proposals for future revisions of or amendments to this Standard. When 

acting as the Standing Committee, the procedures 

for the development of Voluntary Products Standards of the U.S. Department of Commerce shall be 

applicable. The Department of Commerce shall 

provide the secretariat and appoint a chairman 

for the Standing Committee.

9.1.2 To cooperate with the U.S. Department 

of Commerce in establishing and making continuously available basic standards for lumber size, 

pattern, quality, inspection, and reinspection for 

use by industry and trade.

9.1.3 To determine the criteria by which the 

Board shall adjudge and approve the following as 

being in conformance with this Standard:

9.1.3.1 Any published rules.

9.1.3.2 The competency, reliability, and adequacy of the facilities provided by agencies publishing 

grading rules for the purpose of lumber certification, inspection, reinspection, and supervision of 

grade marking.

9.1.3.3 The competency, reliability, and adequacy of the facilities provided by non-rules writing 

agencies participating in this program that do not 

publish grading rules.

9.1.4 To advise the Board with respect to the 

interpretation or application of this Standard and 

the detailed requirements defined and established 

by the ALSC.

9.1.5 To fix, after consultation with the agencies participating in the use of its facilities, such 

charges and fees as the ALSC finds to be necessary to cover the actual cost, including reserves 

and provisions for contingencies, of carrying out 

its functions, those of the Board, and the NGRC. 

Such charges and fees shall be assessed at a uniform proportionate rate against the agencies par-
25

ticipating in the use of the facilities of the ALSC. 

The accreditation of any agency not paying its assessment within 60 days after notification by the 

Secretary of the ALSC shall be revoked by the 

Board.

9.2 Appointment of members The principal and alternate members shall be appointed by 

the Secretary of Commerce for terms of not less

than two nor more than five years.

9.3 Composition of ALSC-- The following 

procedures shall apply in making appointments to 

the ALSC.

9.3.1 A rules-writing agency is one that participates in this program and that formulates, publishes, and maintains grading rules and maintains inspection facilities covering the various 

lumber species. Each rules-writing agency may 

nominate a principal and alternate for each member allotted to that agency. Principal members 

and their alternates shall be appointed from the

nominees furnished by each agency as follows:

Agency Members

Allotted

Southern Pine Inspection Bureau 2

Western Wood Products Association 2

Pacific Lumber Inspection Bureau 2

Redwood Inspection Service 1

Northeastern Lumber Manufacturers

Association 2

National Lumber Grades Authority 1

Each other agency qualifying under

this category 1

9.3.2 A non-rules writing agency (NRWA) is 

an agency that participates in this program 

and that does not publish grading rules. In the 

event that there are three or more NRWAs 

participating in this program, each NRWA 

may nominate one principal and alternate 

member and three principal members and 

their alternates shall be appointed from among 

the nominees so furnished. In the event that 

there are only two NRWAs participating in the 

program, each NRWA may nominate a principal and alternate member and, in addition, the 

two existing NRWAs may together nominate a 

third principal and alternate member, and 

three principal members and their alternates 

shall be appointed from among the nominees 

so furnished. In the event that there is only 

one NRWA participating in the program, the 

single NRWA may nominate up to two principal members and two alternates, and two principal members and their alternates shall be 

appointed from the nominees so furnished.

9.3.3 Firms or organizations within lumber 

specifying, distributing, and consuming groups, at 

the request of the Secretary of Commerce, may 

nominate a principal and an alternate for each 

member allotted. Principal members and their alternates shall be appointed from those groups as 

follows:

Groups Members

Allotted

Lumber Distributors & Wholesalers 2

Lumber Retailers 2

Wood Using Industries 2

General Contractors 1

Home Builders 1

Architects 1

Engineers 1

Wood Treating Industry 1

9.3.4 The Secretary of Commerce may appoint 

consumer-at-large principal members and their 

alternates to represent the general public.

9.3.5 Each nomination shall be submitted to 

the Secretary of Commerce by the appropriate 

agency, firm, or organization upon request or 

whenever a vacancy occurs in the segment represented. Each nomination shall contain the following:
26

9.3.5.1 A summary of the qualifications of the 

nominee.

9.3.5.2 A statement of the method or procedure 

by which the nominee was selected and the procedures under which the nominee will exercise the

responsibility of membership for the agency or industry segment represented. 

9.3.5.3 A statement of any interests, financial or 

otherwise, which the nominee has in agencies or 

segments of the industry other than the one the 

nominee represents.

9.3.5.4 For agencies submitting more than one 

nominee, a listing in the order of priority for appointment.

9.3.6 Ex officio, non-voting principal and alternate members may be appointed by the Secretary of Commerce from the following Federal 

agencies:

Department of Defense

Department of Agriculture

Department of Interior

General Services Administration

Department of Housing & Urban Development 

National Institute of Standards & Technology

9.3.7 Balance of representation Upon request, the Secretary of Commerce may consider 

making changes in the constitution of the ALSC 

or making additional appointments to ensure that 

the ALSC has a balance of interest and is not 

dominated by a single interest category. In such 

considerations, the Secretary of Commerce shall 

consult the ALSC for advice regarding balance

and the criteria by which it may be determined.

9.4 ALSC secretary--Except as provided in 

9.1.1, the manager or executive officer of the 

Board, employed as provided in 10.3, shall serve 

as the Secretary of the ALSC.

9.5 Transaction of business

9.5.1 Meetings--A majority of the members of 

the ALSC representing agencies which formulate, 

publish, and maintain grading rules and maintain 

inspection facilities, together with a majority of 

the other members, shall constitute a quorum for 

the transaction of business. A vote of the majority 

of those present shall decide any question that 

comes before a meeting; but if at any meeting of 

the ALSC there shall be less than a quorum present, a majority of those present shall adjourn the 

meeting or act on the subjects before it, subject to 

ratification in writing by the respective majorities 

which constitute a quorum.

9.5.2 Correspondence-- Business that has 

not been previously presented at a meeting of the 

ALSC shall be held until the next meeting or 

transacted by correspondence in accordance with 

rules to be established by the ALSC.

10. BOARD OF REVIEW

10.1 Autonomy of Board-- The Board shall

be an autonomous body functioning under by-laws 

approved by the ALSC and consistent with Section 10.

10.2 Composition, election, terms, compensation, and removal - The Board shall be 

composed of three members, none of whom shall 

be members of the ALSC or affiliated with an accredited agency or any member of an accredited 

agency.

10.2.1 The chairman of the ALSC shall appoint 

a spokesperson for each of three membership 

groups within the ALSC that shall each nominate 

one potential member of the Board. The spokesperson shall determine and report the decision of 

the group to the Chairman along with a summary 

of the qualifications of the nominee and a statement of any interests, financial or otherwise, 

which the nominee has in the lumber industry. 

Board members shall be nominated as follows:
27

10.2.1.1 One member by majority decision of 

those ALSC members representing the accredited

rules-writing agencies.

10.2.1.2 One member by majority decision of 

those members representing the accredited nonrules-writing lumber inspection agencies.

10.2.1.3 One member by majority decision of 

those remaining ALSC members representing 

other interests.

10.2.1.4 The name of the nominee shall be submitted to the Department of Commerce prior to 

election and shall be accompanied by a summary 

of the qualifications of the nominee and an attestation that the requirements of 10.2 and 10.2.1 

have been met.

10.2.2 Election--Board members shall be elected by the members of the ALSC by a majority of 

those voting. In the event that a nominee designated under 10.2.1.1, 10.2.1.2 or 10.2.1.3 fails to 

receive a majority of the votes cast at any election, 

a new nominee shall be designated in accordance 

with the procedure set forth in 10.2.1.1, 10.2.1.2

or 10.2.1.3.

10.2.3 Terms--The three members of the Board 

shall be elected for terms, respectively, of three 

years, two years, and one year, or until their successors are duly elected. Annually thereafter, one 

member shall be elected for a term of three years 

or until a successor is duly elected. Vacancies on 

the Board by reason of death, resignation, or removal shall be filled at any regularly called committee meeting subject to the provisions of 10.2.1, 

10.2.2 and 9.5.2. Any person elected to fill a vacancy shall serve the unexpired term of the predecessor.

10.2.4 Compensation--The ALSC shall fix and 

pay compensation to the members of the Board 

and shall reimburse them for all reasonable expenses incurred in fulfilling their duties.

10.2.5 Removal--The removal of any Board 

member shall require a vote of not less than twothirds of all the members of the ALSC, with the 

concurrence of the Department of Commerce.

10.3 Board manager--The Board shall select 

and employ a salaried manager or other executive 

officer, subject to the approval of the ALSC, who 

shall assume the responsibilities and perform the 

duties delegated by the ALSC or the Board. Such 

manager or executive officer shall not be in the 

employment of any lumber organization, company, or inspection agency while employed by the 

Board.

10.4 Certification functions--Upon application, the Board shall examine and certify the following as conforming to the requirements of this 

Standard and to additional detailed requirements 

established by the ALSC: Grade strength ratios, 

nomenclature, descriptions of grades published by 

the NGRC and grading rules published by accredited, competent and reliable agencies having adequate facilities for mill inspection and for reinspection of lumber (provided that no such rules for 

any species in any region shall be certified if certified published rules and service applicable thereto 

are adequate and already fully and fairly available to all manufacturers, distributors, and consumers of such lumber, on equal terms and conditions without discrimination). Certification shall 

be subject to these conditions:

10.4.1 Rules conform to the basic requirements 

of this Standard.

10.4.2 Published rules carry specific references 

to such certification.

10.4.3 The originating agency shall make the 

rules fully and fairly available to all manufacturers, distributors, users, and consumers of lumber 

on equal terms and conditions and without discrimination.
28

10.4.4 Subsequent revisions made by the promulgating agency to grading rules that have been 

certified by the Board shall be acted upon within 

90 days after submission to the Board.

10.4.5 Grading rules of an agency shall not be 

certified as conforming to this Standard if the 

Board determines the dimension lumber rules 

therein fail to conform to the provisions of the National Grading Rule for dimension lumber established pursuant to Section 11 of this Standard.

10.5 Accreditation functions--Upon application, the Board shall examine and accredit 

rules-writing agencies and non-rules-writing 

agencies as conforming to the requirements of this 

Standard and to additional requirements established by the ALSC. Accreditation shall be subject 

to these conditions:

10.5.1 The competency, reliability, and adequacy of the facilities provided by agencies participating in this program for the purposes of lumber 

certification, inspection, reinspection, or supervision of grade marking.

10.5.2 The adequacy of the procedure followed 

in authorizing mills to grade mark when providing adequate supervisory service. 

10.5.3 The continuing conformance of grading 

rules to this Standard.

10.5.4 The continuing competency and adequacy of performance of agencies.

10.6 Withdrawal of accreditation--If at 

any time the practices of any accredited agency 

are found not in conformity with this Standard 

and other requirements adopted by the ALSC, 

and if, after due notice in writing to that effect, 

according to established procedures, those practices shall not have been brought into conformity 

with such standards and other requirements by 

the agency concerned, the Board is empowered to 

revoke all previous accreditation granted that 

agency.

10.7 Actions of Board--In all actions in relation to the certification of grading rules, accreditation of agencies and inspection facilities, and 

grade marking practices, the Board shall proceed 

in a fair and nondiscriminatory manner giving 

full and due consideration to the past experience 

and performance of agencies seeking accreditation, and shall apply uniform standards of judgment in making all determinations. In the matter 

of inspection agencies, definite requirements as to 

the integrity, competency and adequacy of the 

agency, and the adequacy of its facilities shall be 

established, but all such requirements shall be 

uniformly applied with respect to all agencies 

seeking accreditation from the Board. No inspection agency that is controlled by any person or 

firm whose own products are subject to its inspection and certification shall be accredited. Inspection services furnished by buyers and users for inspection of their own purchases shall not be accredited by the Board.

10.8 Availability of Board--The facilities of 

the Board shall be available at all times on equal 

terms to any affected party. The Board's facilities 

shall also be available to all lumber inspection 

agencies, without favor or discrimination and 

without any requirement for joining or otherwise 

subscribing to any trade association or supporting 

any service or activity other than those of grading, 

standardization, grade marking, and inspection 

that fall within the jurisdiction of the Board.

10.9 Enforcement--The Board shall adopt, 

subject to prior approval by the ALSC, and administer rules, regulations, and sanctions to ensure 

the continued competency, reliability, and integrity of accredited agencies providing inspection services.

10.10 Board hearings--Any party affected by 

a decision or action of the Board shall have the 

right to require the Board to hold a hearing at 
29

which such party may appear personally or be 

represented by counsel to present supporting evidence and argument of the party's position in accordance with procedures established by the 

Board.

10.11 Reports of action--The Board shall 

within 30 days following an official action make 

such official action public.

11. NATIONAL GRADING RULE 

COMMITTEE

11.1 Autonomy of NGRC--The National 

Grading Rule Committee (NGRC) shall be an autonomous body functioning under by-laws (providing, among other things, for the appointment of 

subcommittees) approved by the ALSC. The bylaws shall be reviewed at least every 5 years and 

reaffirmed or revised, as appropriate.

11.2 Functions of the NGRC--The NGRC 

shall establish, maintain, and make fully and fairly available grade-strength ratios, nomenclature, 

and descriptions of grades for dimension lumber 

conforming to this Standard. Grading rules of an 

agency shall not be certified as conforming to this 

Standard if the Board determines that the dimension lumber rules therein fail to conform to the 

provisions of the National Grading Rule for dimension lumber established pursuant to this section.

11.3 Composition of NGRC--In the interest 

of obtaining balanced views, the NGRC shall be 

composed of persons representing the following 

that desire to participate:

Organization Number of

Members

Southern Pine Inspection Bureau 2

Western Wood Products Association 2

Pacific Lumber Inspection Bureau 2

Redwood Inspection Service 1

Northeastern Lumber Manufacturers

Association, Inc. 2

International Code Council 1

National Fire Protection Association 1

National Association of Home Builders 1

National Lumber Grades Authority 1

American Society of Civil Engineers 1

American Institute of Architects 1

Consumers 1

Lumber Wholesalers 1

Lumber Retailers 1

U.S. Non-rules Writing Agencies 2

Ex officio, non-voting members shall be appointed 

from the following Federal agencies that desire to 

participate:

Department of Housing and Urban

Development 1

Defense Logistics Agency 1

Forest Products Laboratory 1

National Institute of Standards and

Technology 1

11.4 Appointment of members and 

chairman--Members of the NGRC shall be competent in the field of lumber technology. Every 

five years each organization or group of organizations desiring to participate and entitled to representation shall appoint a principal member and 

alternate for each member to which it is entitled. 

The ALSC shall appoint the principal member 

and alternate representing consumer organizations. The Chairman of the NGRC shall be elected every 5 years by the NGRC from among its 

members.

11.5 Transaction of business—A majority 

of members representing rules-writing agencies 

and a majority of the other members shall constitute a quorum to conduct business. Each member 

shall have one vote. The majority vote of those 

present and voting at a meeting shall prevail.

12. REFERENCES
30

12.1 ASTM Standards9

D9-12 Standard Terminology Relating to Wood

and Wood Based Products

D1165-18 Standard Nomenclature of Commercial 

Hardwoods and Softwoods

D4444-18 Standard Test Methods for Laboratory 

Standardization and Calibration of HandHeld Moisture Meters

D7438-13 Standard Practice for Field Calibration 

and Application of Hand-Held Moisture Meters

SI10-16 IEEE/ASTM SI 10 American National 

Standard for Use of the International 

System of Units (SI): The Modern Metric 

System

12.2 Other publications

Little, Elbert, Jr., Checklist of United States Trees 

(Native and Naturalized), Agriculture 

Handbook No. 541, Forest Service, U.S. 

Department of Agriculture, Washington 

DC 20090-6090, 1979.

9 ASTM Standards are available from ASTM International, 

100 Barr Harbor Drive, West Conshohocken, PA 19248-

2959; telephone (610) 832-9500; www.astm.org.
31

APPENDIX A COMMERCIAL NAMES OF THE PRINCIPAL SOFTWOOD SPECIES

The commercial names listed below are intended to provide a correlation between commercial names 

for lumber and the botanical names of the species from which the lumber is to be manufactured. In 

some instances more than one species is associated with a single commercial name. For stress-graded 

lumber, the species to be associated with a commercial name will be determined in accordance with 

6.3.2.1. These commercial names are to be used in grading rule descriptions and in specifications [see 

2.15]. The provisions of this Standard also apply to lumber manufactured from hardwood species or 

lumber manufactured from foreign species when the species is included in rules certified by the Board 

of Review. The information contained herein is a partial list of commercial names of the principal 

softwood species and species groups. Additional species and species groups are provided in ASTM 

Standard D 1165-18 and the rules certified by the Board of Review.

Commercial Official Common

Species or Species Group Names10 Tree Names11 Botanical Names

CEDAR:

Alaska Cedar Alaska-cedar Chamaecyparis

nootkatensis

Incense Cedar incense-cedar Libocedrus decurrens

Port Orford Cedar Port-Orford-cedar Chamaecyparis

lawsoniana

Eastern Red Cedar eastern redcedar Juniperus virginiana

southern redcedar J. silicicola

Western Red Cedar western redcedar Thuja plicata

Northern White Cedar northern white-cedar T. occidentalis

Southern White Cedar Atlantic white-cedar Chamaecyparis thyoides

CYPRESS12

Baldcypress baldcypress Taxodium distichum

Pond cypress pond cypress T. distichum var. nutans

DOUGLAS FIR

Douglas Fir13 Douglas-fir Pseudotsuga menziesii

Bigcone Douglas fir Bigcone Douglas fir P. macrocarpa

FIR:

Balsam Fir14 balsam fir Abies balsamea

10 The commercial names for species represent those commonly accepted. Some grading rules certified by the Board provide 

for the inclusion of additional species under the established names.

11 The official common tree names conform to the Checklist of United States Trees (Native and Naturalized), Agriculture 

Handbook No. 541 (1979), and are sometimes used as names for lumber. In addition to the official common names for a 

species, the Handbook lists other names by which the species and the lumber produced from it are sometimes designated.

12Cypress includes types designated as Red Cypress, White Cypress, and Yellow Cypress. Red Cypress is frequently classified 

and sold separately from the other types.

13 Douglas fir from Arizona, Colorado, Nevada, New Mexico and Utah is recognized as Douglas fir-South. 14 Balsam fir lumber is sometimes designated either as Eastern fir or as Balsam.
32

Commercial Official Common

Species or Species Group Names8 Tree Names9 Botanical Names

FIR (continued)

Fraser Fir Fraser fir A. fraseri

Noble Fir noble fir A. procera

Alpine Fir subalpine fir (alpine fir) A. lasiocarpa

California Red Fir California red fir A. magnifica

Grand Fir grand fir A. grandis

Pacific Grand Fir Pacific silver fir A. amabilis

White Fir white fir A. concolor

HEMLOCK:

Carolina Hemlock Carolina hemlock Tsuga caroliniana

Eastern Hemlock eastern hemlock T. canadensis

Mountain Hemlock mountain hemlock T. mertensiana

Western Hemlock western hemlock T. heterophylla

JUNIPER:

Western Juniper alligator juniper Juniperus deppeana

Rocky Mountain juniper J. scopulorum

Utah juniper J. osteosperma

western juniper J. occidentalis

LARCH:

Western Larch western larch Larix occidentalis

Tamarack tamarack L. laricina

PINE:

Bishop Pine Bishop pine Pinus muricata

Digger Pine Digger pine P. sabiniana

Knobcone Pine knobcone pine P. attenuata

Coulter Pine Coulter pine P. coulteri

Jeffrey Pine Jeffrey pine P. jeffreyi

Jack Pine jack pine P. banksiana

Limber Pine limber pine P. flexilis

Lodgepole Pine lodgepole pine P. contorta

Norway Pine red pine P. resinosa

Pitch Pine pitch pine P. rigida

Ponderosa Pine ponderosa pine P. ponderosa

Radiata/Monterey Pine Monterey pine P. radiata

Sugar Pine sugar pine P. lambertiana

Whitebark Pine whitebark pine P. albicaulis

Idaho White Pine western white pine P. monticola

Northern White Pine eastern white pine P. strobus
33

Commercial Official Common

Species or Species Group Names8 Tree Names9 Botanical Names

PINE (continued)

Longleaf Pine15 longleaf pine P. palustris

slash pine P. elliottii

Southern Pine (Major) loblolly pine P. taeda

longleaf pine P. palustris

shortleaf pine P. echinata

slash pine P. elliottii

Southern Pine (Minor) pond pine P. serotina

Virginia pine P. virginiana

sand pine P. clausa

spruce pine P. glabra

REDWOOD:

Redwood redwood Sequoia sempervirens

SPRUCE:

black spruce black spruce Picea mariana

red spruce red spruce P. rubens

white spruce white spruce P. glauca

Blue Spruce blue spruce P. pungens

Engelmann Spruce Engelmann spruce P. engelmannii

Sitka Spruce Sitka spruce P. sitchensis

Norway Spruce Norway spruce P. abies

YEW:

Pacific Yew Pacific yew Taxus brevifolia

15 The commercial requirements for Longleaf Pine lumber are that not only must it be produced from trees of the botanical 

species of Pinus elliottii and Pinus palustris, but each piece in addition must average either on one end or the other not less 

than six annual rings per inch and not less than one-third summerwood. Longleaf Pine lumber is sometimes designated as 

Pitch Pine in the export trade.
34

APPENDIX B DEFINITIONS OF TERMS USED IN DESCRIBING

STANDARD GRADES OF LUMBER

B1. SI 10-2016 was used as the authoritative 

standard in developing the metric dimensions 

found in this Standard. Metric dimensions are 

calculated at 25.4 millimeters (mm) times the 

dressed dimension in inches. The nearest mm is 

significant for dimensions greater than 1/8 inch,

and the nearest 0.1 mm is significant for dimensions equal to or less than 1/8 inch.

The rounding rule for dimensions greater than 

1/8 inch: if the digit in the tenths of mm position 

(the digit after the decimal point) is less than 5, 

drop all fractional mm digits; if greater than 5 or 

it is 5 followed by at least one non-zero digit, 

round one mm higher; if 5 followed by only zeroes, retain the digit in the unit position (the 

digit before the decimal point) if it is even or increase it one mm if it is odd.

The rounding rule for dimensions equal to or 

less than 1/8 inch: if the digit in the hundredths 

of mm position (the second digit after the decimal point) is less than 5, drop all digits to the 

right of the tenths position; if greater than 5 or it 

is 5 followed by at least one non-zero digit, round 

one-tenth mm higher; if 5 followed by only zeros, 

retain the digit in the tenths position if it is even 

or increase it one-tenth mm if it is odd.

CAUTION: Use great care when converting 

board feet, based on NOMINAL cross-sectional 

dimensions, to cubic meters of lumber, based on 

DRESSED cross-sectional dimensions. This is 

explained on page 32 of the IEEE/ASTM SI 10-

2002 by the following note: “(9) No conversion is 

given for “board foot” because “board foot” is not

a well-defined unit of volume. Calculation of the 

number of board feet in a piece of lumber is 

based on the nominal dimensions of the cross 

section.”

Unfortunately, many older handbooks and dictionaries and some current references still contain erroneous or vague information about volume conversions to SI metric. The amount of 

dressing can also affect the cross-sectional dimensions. Therefore, use extra care when making conversions from NOMINAL board foot to 

actual cubic meters.

In case of a dispute on size measurements, the 

conventional (inch) method of measurement 

shall take precedence.

B2. Definitions of terms used in describing standard grades of lumber:

air dried-- seasoned by exposure to the atmosphere, in the open or under cover, without 

artificial heat.

all-heart-- of heartwood throughout; that is, 

free of sapwood.

annual ring-- denotes the amount of growth for 

a tree in a single year.

bark pocket-- patch of bark partially or wholly 

enclosed in the wood. Classified by size the 

same as pitch pockets.

bevel siding— a board that has been resawn 

diagonally to be used to clad the exterior of a 

building.

rabbeted bevel siding—bevel siding 

with a rabbeted joint milled on the 

reverse of the thick edge to facilitate 

alignment of pieces.

blemish-- anything marring the appearance of 

lumber.

bow-- see WARP.
35

boxed heart-- with the pith enclosed in the 

piece.

bright-- unstained.

burl-- a distortion of grain, usually caused by 

abnormal growth due to injury of the tree. 

The effect of burls is assessed in relation to 

knots.

Ceiling—a piece of patterned, tongue and 

grooved lumber, used to cover the ceiling of a

room, porch or other partially enclosed areas.

check-- a separation of the wood normally occurring across or through the annual rings 

and usually as a result of seasoning.

roller check-- a crack in the wood structure caused by a piece of cupped lumber being flattened in passing between the machine rollers.

surface check— a separation that occurs on a face of a piece.

small check-- not over 0.8 mm (1/32 

inch) wide or 102 mm (4 inch) long.

medium check-- not over 0.8 mm (1/32 

inch) wide or 254 mm (10 inch) long.

large check-- over 0.8 mm (1/32 inch) 

wide or longer than 254 mm (10 inch) 

or both.

through check-- a separation that extends from one surface of a piece to 

the opposite or adjoining surface.

chipped grain-- a barely perceptible irregularity in the surface of a piece caused when particles of wood are chipped or broken below 

the line of cut. It is too small to be classed as 

torn grain and is not considered unless in excess of 25 percent of the surface involved.

chip marks-- shallow depressions or indentations on or in the surface of dressed lumber 

caused by shavings or chips getting embedded in the surface during dressing.

very light chip marks-- not over 0.4 

mm (1/64 inch) deep.

light chip marks— not over 0.8 mm 

(1/32 inch) deep.

medium chip marks-- not over 1.6 mm 

(1/16 inch) deep.

heavy chip marks-- not over 3.2 mm 

(1/8 inch) deep.

clear-- free or practically free of all blemishes, 

characteristics, or defects.

compression wood-- abnormal wood that forms 

on the underside of leaning and crooked coniferous trees. It is characterized, aside from 

its distinguishing color, by being hard and 

brittle and by its relatively lifeless appearance. Compression wood shall be limited in 

effect to other appearance or strength reducing characteristics permitted in the grade.

corner-- the intersection of two adjacent faces.

crook-- see WARP.

cross break-- separation of the wood across the 

width.

crosscutting-- cutting with a saw across the 

width.

cup-- see WARP.

cutting-- resulting pieces after crosscutting 

and/or ripping.

decay (unsound wood)-- a disintegration of the 

wood substance due to action of wooddestroying fungi, and is also known as dote 

or rot.

advanced decay-- an older stage of decay in which disintegration is recognized because the wood has become 

punky, soft, spongy, stringy, shaky, 

pitted, or crumbly. Decided discoloration or bleaching of the rotted wood is 

often apparent.

heart center decay-- a localized decay 

developing along the pith in some 

species and is detected by visual in-
36

spection. Heart center decay develops 

in the living tree and does not progress further after the tree is cut.

honeycomb-- similar to white specks but 

the pockets are larger. Where permitted in the grading rules, it is so limited that it has no more effect on the 

intended use of the piece than other

characteristics permitted in the same 

grade. Pieces containing honeycomb 

are no more subject to decay than 

pieces which do not contain it.

incipient decay-- an early stage of decay 

in which disintegration of the wood 

fibers has not proceeded far enough to 

soften or otherwise change the hardness of the wood perceptibly. It is 

usually accompanied by a slight discoloration or bleaching of the wood.

peck-- channeled or pitted areas or pockets found in cedar and cypress. Wood 

tissue between pecky areas remains

unaffected in appearance and 

strength. All further growth of the 

fungus causing peckiness ceases after 

the trees are felled.

pecky-- characterized by PECK

pocket rot-- decay which appears in the 

form of a hole, pocket, or area of soft 

rot, usually surrounded by apparently 

sound wood.

water soak or stain-- water-soaked area in heartwood, usually interpreted 

as the incipient stage of certain wood 

rots.

white specks-- small white or brown pits 

or spots in wood caused by the fungus 

Fomes pini. It develops in the living 

tree and does not develop further in 

wood in service. Where permitted in

grading rules, it is so limited that it

has no more effect on the intended 

use of the pieces than other characteristics permitted in the same grade. 

Pieces containing white speck are no 

more subject to decay than pieces 

which do not contain it.

degrades-- pieces which on reinspection prove

of lower quality than the grade in which they 

were shipped.

diagonal grain-- a deviation in the slope of 

grain caused by sawing at an angle with the 

bark of the tree. See SLOPE OF GRAIN.

dry-- lumber of less than nominal 5-inch thickness which has been seasoned or dried to a 

maximum moisture content of 19 percent. 

Lumber of nominal 5-inch or greater in 

thickness (timbers) is often manufactured

and sold without drying. When the maximum moisture content is specified for lumber 

of nominal 5-inch or greater thickness, it 

shall be in accordance with the provisions of 

the applicable lumber grading rules certified 

by the Board, which for some species defines 

dry lumber as having a maximum moisture 

content higher than 19 percent [see 2.7].

eased edge-- slightly rounded surfacing on pieces of lumber to remove sharp corners. Note: 

Lumber nominal 4 inch or less in thickness is 

frequently shipped with eased edges unless 

otherwise specified.

edge-- either : 1) the narrow face of rectangularshaped pieces, or 2) the corner of a piece at 

the intersection of two longitudinal faces, or 

3) in stress grades, that part of the wide face 

nearest the corner of the piece.

edge grain (EG) [vertical grain (VG)] [rift 

grain]-- a piece or pieces sawn at approximately right angles to the annual growth 

rings so that the rings form an angle of 45 

degrees or more with the surface of the piece.

equilibrium moisture content– the moisture 

content at which wood neither gains nor loses moisture when surrounded by air at a given relative humidity and temperature.

Finish— a high-quality piece of lumber graded 

for appearance, often used for interior trim 

or cabinet work.
37

firm red heart-- a stage of incipient decay 

characterized by a reddish color in the 

heartwood which does not render the wood 

unfit for the majority of yard purposes.

flat grain (FG) [slash grain (SG)]-- a piece or 

pieces sawn approximately parallel to the 

annual growth rings so that all or some of 

the rings form an angle of less than 45 degrees with the surface of the piece.

Flooring— a tongue and grooved piece of lumber typically used as a finished floor.

f.o.h.c. (free of heart centers)-- without pith 

(side cut). An occasional piece, when showing 

pith for not more than 1/4 the length on the 

surface, shall be accepted.

free of wane-- without wane but with either 

eased or square edges. (see WANE)

grain-- the fibers in wood and their direction, 

size, arrangement, appearance, or quality.

Green— lumber of less than nominal 5-inch 

thickness, which has a moisture content in 

excess of 19 percent. For lumber of nominal 

5-inch or greater thickness (timbers), green 

shall be defined in accordance with the provisions of the applicable lumber grading 

rules certified by the Board [See 2.11].

gum pocket-- an opening between growth rings 

which contains or has contained resin, or 

bark, or both.

gum seam-- check or shake filled with gum.

gum spot-- an accumulation of gumlike substance occurring as a small patch. Often occurs in conjunction with a bird-peck or other 

injury to the growing wood.

gum streak-- a well-defined accumulation of 

gum in more or less regular streak. Classified as pitch streaks.

heart center-- the pith or center core of the log.

heart face-- face side free of sapwood.

heart shake-- see SHAKE--PITH SHAKE.

heartwood-- the inner core of the tree trunk 

comprising the annual rings containing nonliving elements. In some species, heartwood 

has a prominent color different from sapwood. Heartwood and sapwood of equivalent 

character are compared as follows:

with regard to strength, heartwood

and sapwood are equal. No requirement of heartwood is made when 

strength alone is the governing factor.

with regard to durability, heartwood 

is more durable than sapwood. When 

wood is to be exposed to decayproducing conditions without preservative treatment, it is permissible 

to specify the minimum percentage of 

heartwood to be present in all pieces 

of lumber in a shipment.

with regard to preservatives, sapwood 

takes preservative treatment more 

readily than heartwood.

hit-and-miss--a series of skips not over 1.6 mm 

(1/16 inch) deep with surfaced areas between.

hit-or-miss-- lumber that is completely or partly 

surfaced or entirely rough with a maximum 

scantness of 1.6 mm (1/16 inch).

holes-- openings that either extend partially or 

wholly through a piece. An alternate designation for holes which extend only partially 

through a piece is surface pits. Holes are 

classified by size as follows: 

pin hole-- not over 1.6 mm (1/16 inch) in 

diameter.

medium hole— (small hole) not over 6 

mm (1/4 inch) in diameter.

large hole-- not over 25 mm (1 inch) in 

diameter.
38

very large hole-- over 25 mm (1 inch) in 

diameter.

kiln-dried— seasoned in a chamber by means 

of artificial heat.

knife marks-- the imprints or markings of the 

machine knives on the surface of dressed 

lumber.

very slight knife marks-- marks that 

are visible only from a favorable angle 

and are perfectly smooth to the touch.

slight knife marks-- marks that are 

readily visible but evidence no unevenness to the touch.

knot-- a portion of a branch or limb that has become incorporated in a piece of lumber. In 

lumber, knots are classified as to form, size, 

quality, and occurrence.

knot form--

oval knot-- produced when the limb is 

cut at slightly more than a right angle 

to the long axis.

round knot-- produced when the limb is 

cut at approximately right angles to 

its long axis.

spike knot-- produced when the limb is 

cut either lengthwise or diagonally.

knot size--

pin knot-- not over 13 mm (1/2 inch) in 

diameter.

small knot-- not over 19 mm (3/4 inch) 

in diameter.

medium knot-- not over 38 mm (1-1/2 

inch) in diameter.

large knot-- over 38 mm (1-1/2 inch) in 

diameter.

knot quality--

black knot-- results from a dead branch 

which the wood growth of the tree has 

surrounded.

decayed knot-- softer than the surrounding wood, and containing advanced decay.

encased knot-- not intergrown with the 

annual rings of the surrounding 

wood.

firm knot— solid across its face but contains incipient decay.

fixed knot-- retains its place in dry lumber under ordinary conditions but is 

movable under pressure though not 

easily pushed out.

hollow knot-- a sound knot containing a 

hole greater than 6 mm (1/4 inch) in 

diameter. The through opening of a 

hollow knot is limited to the size of 

other holes permitted.

intergrown knot— a knot whose annual 

rings are partially or completely intergrown on one or more faces with 

the annual rings of the surrounding 

wood.

loose knot-- not firmly fixed; a knot not 

held tightly in place by growth, shape,

or position.

pith knot-- sound in all respects except it 

contains a pith hole not over 6 mm 

(1/4 inch) in diameter.

red knot-- knot that results from a live 

branch grown in the tree and is intergrown with the surrounding wood.

sound knot— contains no decay. 

star-checked knot-- has radial checks.

tight knot-- so fixed by growth, shape, or 

position that it retains its place in the 

piece.

unsound knot— contains decay.

water-tight knot-- has annual rings 

completely intergrown with those of 

the surrounding wood on one surface 

of the piece, and it is sound on that 

surface.

knot occurrence--

branch knots-- two or more divergent 

knots sawed lengthwise and tapering 

toward the pith at a common point.

corner knot-- located at the intersection 

of adjacent faces.

knot cluster— two or more knots 

grouped together as a unit with the 
39

fibers of the wood deflected around 

the entire unit. A group of single 

knots is not a knot cluster.

single knot-- occurs by itself. The fibers 

of the wood being deflected around it.

loosened grain-- a grain separation or loosening between springwood and summerwood 

without displacement.

very light loosened grain-- not over 0.4 

mm (1/64 inch) separation.

light loosened grain-- not over 0.8 mm 

(1/32 inch) separation.

medium loosened grain-- not over 1.6 

mm (1/16 inch) separation.

heavy loosened grain-- not over 3.2 mm 

(1/8 inch) separation.

very heavy loosened grain-- over 3.2 

mm (1/8 inch) separation.

lumber-- Lumber is defined as a manufactured 

product derived from a log through sawing or 

planing. 

machine bite-- a depressed cut of the machine 

knives at the end of a piece.

very light machine bite-- not over 0.4 

mm (1/64 inch) deep.

light machine bite-- not over 0.8 mm 

(1/32 inch) deep.

medium machine bite-- not over 1.6 

mm (1/16 inch) deep.

heavy machine bite-- not over 3.2 mm 

(1/8 inch) deep.

very heavy machine bite— over 3.2 mm 

(1/8 inch) deep.

machine burn-- a darkening of the wood due to 

overheating by machine knives or rolls when 

pieces are stopped in the machine.

machine gouge-- a groove cut by the machine 

below the desired line.

very light machine gouge-- not over 0.4 

mm (1/64 inch) deep.

light machine gouge-- not over 0.8 mm 

(1/32 inch) deep.

medium machine gouge-- not over 1.6 

mm (1/16 inch) deep.

heavy machine gouge-- not over 3.2 

mm (1/8 inch) deep.

very heavy machine gouge-- over 3.2 

mm (1/8 inch) deep.

machine offset-- an abrupt dressing variation 

in the edge surface which usually occurs near 

the end of the piece without reducing the 

width or without changing the plane of the 

wide surface.

very light machine offset-- a variation 

not over 0.4 mm (1/64 inch).

light machine offset-- a variation not 

over 0.8 mm (1/32 inch).

medium machine offset-- a variation 

not over 1.6 mm (1/16 inch).

heavy machine offset-- a variation not 

over 3.2 mm (1/8 inch).

very heavy machine offset-- a variation 

over 3.2 mm (1/8 inch).

metric units— See B1.

mismanufacture-- includes all defects or blemishes, produced in manufacturing. See 

CHIPPED GRAIN, HIT-AND-MISS, HITOR-MISS, LOOSENED GRAIN, MACHINE 

BURN, MACHINE GOUGE, MISMATCHED 

LUMBER, RAISED GRAIN, SKIP, TORN 

GRAIN, and VARIATION IN SAWING.

mismatch-- an uneven fit in worked lumber 

when adjoining pieces do not meet tightly at 

all points of contact or when the surfaces of 

adjoining pieces are not in the same plane.

slight mismatch-- a barely evident trace 

of mismatch.

very light mismatch-- not over 0.4 mm 

(1/64 inch).

light mismatch-- not over 0.8 mm (1/32 

inch).

medium mismatch— not over 1.6 mm 

(1/16 inch).

heavy mismatch-- not over 3.2 mm (1/8 

inch).
40

mixed grain (MG)— either vertical or flat 

grained pieces or both.

moisture content-- the weight of the water in a 

piece of lumber expressed in a percentage of 

the weight of the piece after being over dried. 

occasional pieces-- not more than 10% of the 

pieces in a parcel or shipment.

partition— a tongue and grooved piece of lumber with the same pattern run on both sides. 

For use where both sides may be exposed.

pitch-- an accumulation of resinous material.

light pitch-- the light but evident presence of pitch.

medium pitch-- a somewhat more evident presence of pitch than in the 

light pitch.

heavy pitch— a very evident accumulation of pitch showing by its color and 

consistency.

massed pitch-- a clearly defined accumulation of solid pitch in a body by itself.

pitch seam-- a shake or check which contains 

pitch.

pitch streak-- a well-defined accumulation of 

pitch in the wood cells in a streak. Pitch 

streaks, with equivalent areas being permissible, are described as follows:

very small pitch streak— 10mm (3/8 

inch) in width and 381 mm (15 inch) 

in length.

small pitch streak-- 1/12 the width and

1/6 the length of the piece.

medium pitch streak-- 1/6 the width 

and 1/3 the length of the piece.

large pitch streak-- not over 1/4 the 

width by 1/2 the length of the surface.

very large pitch streak-- over 1/4 the 

width by 1/2 the length of the surface.

pith-- the small soft core in the structural center 

of a log.

very small pith-- not over 3.2 mm (1/8 

inch) wide and occupies on the face 

surface not over 161 square mm (1/4 

square inch) [3.2 mm by 51 mm (1/8 

inch wide by 2 inch long), or 1.6 mm 

by 102 mm (1/16 inch by 4 inch)]

small pith-- not over 484 square mm 

(3/4 square inch) on the face surface 

[6 mm by 76 mm (1/4 inch by 3 inch), 

5 mm by 102 mm (3/16 inch by 4 

inch), 3.2 mm by 152 mm (1/8 inch by 

6 inch), or 1.6 mm by 305 mm (1/16 

inch by 12 inch)]

free of pith-- the prohibition of pith on or

within the body of the piece.

boxed pith-- pith that is within the four 

faces of an end of a piece.

pocket-- a well-defined opening, between the 

rings of annual growth, which develops during the growth of the tree. It usually contains 

pitch or bark. Pockets are described as follows with equivalent areas being permissible:

very small pocket— 1.6 mm (1/16 inch) 

in width and 76 mm (3 inch) in 

length, or 3.2 mm (1/8 inch) in width 

and 51 mm (2 inch) in length.

small pocket— 1.6 mm (1/16 inch) in 

width and 152 mm (6 inch) in length, 

or 3.2 mm (1/8 inch) in width and 102 

mm (4 inch) in length, or 6 mm (1/4 

inch) in width and 51 mm (2 inch) in 

length.

medium pocket— 1.6 mm (1/16 inch) in 

width and 305 mm (12 inch) in 

length, or 3.2 mm (1/8 inch) in width 

and 203 mm (8 inch) in length, or 10 

mm (3/8 inch) in width and 102 mm 

(4 inch) in length.

large pocket— not over 2581 square 

mm (4 square inches) in area.

very large pocket-- over 2581 square 

mm (4 square inches) in area.

closed pocket-- an opening on one surface only.

open (through) pocket-- an opening on 

opposite surfaces. A through opening 
41

is considered the same as a through 

hole of equal size.

raised grain— a roughened condition of the 

surface of dressed lumber in which the hard 

summerwood is raised above the softer 

springwood, but not torn loose from it.

very light raised grain-- not over 0.4 

mm (1/64 inch). 

light raised grain-- not over 0.8 mm 

(1/32 inch).

medium raised grain-- not over 1.6 mm 

(1/16 inch).

heavy raised grain-- not over 3.2 mm 

(1/8 inch).

resawn lumber-- the product of sawing any 

thickness of lumber to develop thinner lumber.

ripped lumber-- the product of sawing any 

width of lumber to develop narrower lumber.

sapwood-- the outer layers of growth between 

the bark and heartwood that contain the sap.

bright sapwood— sapwood that shows 

no stain and is not limited in any 

grade unless specifically stated in the 

grade description.

sapwood restrictions waived-- a lifting 

of any restrictions in a rule on the 

amount of sapwood permitted in pieces graded under that rule.

bright sapwood no defect (BSND)-- an 

indication that bright sapwood is 

permitted in each piece in any 

amount.

seasoning-- evaporation or extraction of moisture from green or partially dried wood.

shake-- a lengthwise separation of the wood 

which occurs between or through the rings of 

annual growth.

fine shake-- a barely perceptible opening.

light shake-- not over 0.8 mm (1/32 inch) 

wide.

medium shake-- not over 3.2 mm (1/8 

inch) wide.

open shake-- over 3.2 mm (1/8 inch) 

wide.

ring shake-- occurs between the annual 

rings to partially or wholly encircle

the pith.

surface shake-- occurs on only one surface of a piece.

through shake-- extends from one surface of a piece to the opposite or to an 

adjoining surface.

pith shake (heart check or heart 

shake)-- extends through the annual 

rings from or through the pith towards the surface of a piece, and is 

distinguished from a seasoning check 

by the fact that its greatest width is 

nearest the pith, whereas the greatest 

width of a season check in a pithcentered piece is farthest from the 

pith.

side cut-- pith is not enclosed within the four 

sides of the piece.

skip-- area on a piece that failed to surface 

clean. Skips are described as follows:

very light skip--not over 0.4 mm (1/64 

inch) deep.

light skip--not over 0.8 mm (1/32 inch) 

deep.

medium skip--not over 1.6 mm (1/16 

inch) deep.

heavy skip-- not over 3.2 mm (1/8 inch) 

deep.

slope of grain-- the deviation of the line of fibers from a straight line parallel to the sides 

of the piece.

Softwood— one of the group of trees which have 

needle-like or scale-like leaves. The term has 

no specific reference to the softness of the 

wood.

sound-- free of decay.
42

spiral grain-- a deviation in the slope of grain 

caused when the fibers in a tree take a spiral 

course around the trunk of the tree instead of 

the normal vertical course.

split-- a separation of the wood through the 

piece to the opposite surface or to an adjoining surface due to the tearing apart of the 

wood cells.

very short split-- equal in length to 1/2 

the width of the piece.

short split--equal in length to the width 

of the piece and in no case exceeds 1/6 

the length.

medium split-- equal in length to twice 

the width of the piece and in no case 

exceeds 1/6 the length.

long split-- longer than a medium split.

springwood-- the portion of the annual ring 

formed during the early part of the yearly 

growth period. It is lighter in color, less 

dense, and not as strong mechanically as 

summerwood.

square corners-- without eased edges but has 

an allowance for wane in certain grades.

square edged-- free from wane and without 

eased edges.

stained wood-- a discoloration in wood.

stained heartwood or firm red heart--

heartwood that shows a marked variation from the natural color. In 

grades where it is permitted, stained 

heartwood has no more effect on the 

intended use of a piece than other 

characteristics permitted in the 

grade. Note: Stained heartwood ranges from pink to brown, and is not to be 

confused with natural red heart. Natural color is usually uniformly distributed through certain annual rings, 

whereas stains are usually in irregular patches.

stained sapwood— sapwood with discoloration. In grades when it is permitted, stained sapwood has no more 

effect on the intended use of a piece 

than other characteristics permitted 

in the grade but it does affect appearance in varying degrees:

light stained sapwood— a discoloration so slight that it does 

not affect natural finishes.

medium stained sapwood a 

pronounced difference in coloring. Note: Sometimes the usefulness for natural finishes but 

not for paint finishes is affected.

heavy stained sapwood— a so 

pronounced difference in color 

that the grain of the wood is 

obscured, but lumber containing it is acceptable for paint 

finishes.

stained wood resulting from exposure 

to the elements-- discolored wood 

that is permitted in all grades of 

framing and sheathing lumber.

Stepping— lumber designed to be used for stair 

treads. Customarily surfaced three sides and 

bull-nosed on one edge.

stress grades-- lumber having assigned working stresses and modulus of elasticity values 

in accordance with accepted basic principles 

of strength grading, and the provisions of 

6.3.2.1 and 6.3.2.2 of this Standard.

summerwood-- the portion of the annual ring 

formed during the latter part of the yearly 

growth. It is darker in color, more dense, and 

stronger mechanically than springwood.

torn grain-- an irregularity in the surface of a 

piece where wood has been torn or broken 

out by surfacing.

very light torn grain-- not over 0.4 mm 

(1/64 inch) deep.

light torn grain-- not over 0.8 mm (1/32 

inch) deep.
43

medium torn grain-- not over 1.6 mm 

(1/16 inch) deep.

heavy torn grain-- not over 3.2 mm (1/8 

inch) deep.

very heavy torn grain-- over 3.2 mm 

(1/8 inch) deep.

trim-- to cross-cut a piece to a given length.

double-end trimmed (DET)-- lumber 

trimmed square on both ends. Tolerances are found in certified grading 

rules. 

precision-end trimmed (PET)-- lumber 

trimmed square on both ends to uniform lengths with a manufacturing 

tolerance of 1.6 mm (1/16 inch) over

or under in length in 20% of the pieces.

square-end trimmed-- lumber trimmed 

square and having a manufacturing 

tolerance of 0.4 mm (1/64 inch) for 

each nominal 2 inch of thickness or 

width.

Unsound— see DECAY.

variation in sawing-- a deviation from the line 

of cut. 

slight variation--not over 1.6 mm (1/16 

inch) scant in nominal 1-inch lumber, 

3.2 mm (1/8 inch) in nominal 2-inch, 5 

mm (3/16 inch) in nominal 3-inch to 7-

inch, and 6 mm (1/4 inch) in nominal 

8-inch and greater thickness or width.

wane-- bark or lack of wood from any cause, except eased edges, on the edge or corner of a 

piece of lumber.

warp-- any deviation from a true or plane surface, including bow, crook, cup, twist, or any 

combination thereof. Warp restrictions are 

based on the average form of warp as it occurs normally, and any variation from this 

average form, such as short kinks, shall be 

appraised according to its equivalent effect. 

Pieces containing two or more forms of warp 

shall be appraised according to the combined 

effect in determining the amount permissible. In grading rules, warp is classified as 

very light, light, medium, and heavy, and 

applied to each width and length as set forth 

in the various grades in accordance with the 

following provisions:

bow-- a deviation flatwise from a straight 

line drawn from end to end of a piece. 

It is measured at the point of greatest 

distance from the straight line. 

crook-- a deviation edgewise from a 

straight line drawn from end to end of 

a piece. It is measured at the point of 

greatest distance from the straight 

line.

cup-- a deviation in the face of a piece 

from a straight line drawn from edge 

to edge of a piece. It is measured at 

the point of greatest distance from the

straight line.

twist-- a deviation flatwise, or a combination of flatwise and edgewise, in 

the form of a curl or spiral, and the 

amount is the distance an edge of a 

piece at one end is raised above a flat 

surface against which both edges at 

the opposite end are resting snugly.

wavy dressing-- an involvement of more uneven dressing than knife marks.

very light wavy dressing-- not over 0.4 

mm (1/64 inch) deep.

light wavy dressing-- not over 0.8 mm 

(1/32 inch) deep.

medium wavy dressing-- not over 1.6 

mm (1/16 inch) deep.

heavy wavy dressing-- not over 3.2 mm 

(1/8 inch) deep.

very heavy wavy dressing-- over 3.2 

mm (1/8 inch) deep. 
44

APPENDIX C LUMBER INDUSTRY ABBREVIATIONS

These abbreviations are commonly used for softwood lumber, although all of them are not 

necessarily applicable to all species. Additional abbreviations which are applicable to a particular region 

or species shall not be used unless included in certified grading rules.

Abbreviations are commonly used in the forms indicated, but variations such as the use of upperand lower-case type, and the use or omission of periods and other forms of punctuation are not required. 

AD Air-dried

ADF After deducting freight sides

ALS American Softwood Lumber Standard

AV or AVG Average

Bd Board

Bd ft Board foot or feet

Bdl Bundle

Bev Beveled

B/L Bill of lading

BM Board Measure

Btr Better

B&B or B&Btr B and better

B&S Beams and stringers

CB1S Center bead one side

CB2S Center bead two sides

CF Cost and freight

CG2E Center groove two edges

CIF Cost, insurance, and freight

CIFE Cost, insurance, freight, and exchange

Clg Ceiling

Clr Clear

CM Center matched

Com Common

CS Caulking seam

Csg Casing

Cu Ft Cubic foot or feet

CV1S Center Vee one side

CV2S Center Vee two sides

D&H Dressed and headed

D&M Dressed and matched

DB Clg Double-beaded ceiling (E&CB1S)

DB Part Double-beaded partition (E&CB2S)

DET Double end trimmed

Dim Dimension

Dkg Decking

D/S or D/Sdg Drop siding

EB1S Edge bead one side

EB2S Edge bead two sides

E&CB1S Edge and center bead one side
45

E&CB2S Edge and center bead two sides

E&CV1S Edge and center Vee one side

E&CV2S Edge and center Vee two sides

EE Eased edges

EG Edge (vertical) grain

EM End matched

EV1S Edge Vee one side

EV2S Edge Vee two sides

Fac Factory

FAS Free alongside (named vessel)

FBM Foot or board measure

FG Flat (slash) grain

Flg Flooring

FOB Free on board (named point)

FOHC Free of heart center or centers

FOK Free of knots

Frt Freight

Ft Foot or feet

GM Grade marked

G/R or G/Rfg Grooved roofing

HB Hollow back

H&M hit-and-miss

H or M hit-or-miss

Hrt Heart

Hrt CC Heart cubical content

Hrt FAHeart facial area

Hrt G Heart girth

IN Inch or inches

J&P Joists and planks

KD Kiln-dried

Lbr Lumber

LCL Less than carload

LFT or Lin Ft Linear foot or feet

Lgr Longer

Lgth Length

Lin Linear

Lng Lining M Thousand

MBM Thousand (feet) board measure

MC Moisture content

Merch Merchantable

Mldg Moulding

mm Millimeter

No Number

N1ENosed one edge

N2E Nosed two edges

Og Ogee

Ord Order

Par Paragraph

Part Partition
46

Pat Pattern

Pc Piece

Pcs Pieces

PE Plain end

PO Purchase order

P&T Post and timbers

Reg Regular

Res Resawed or resawn

Rfg Roofing

Rgh Rough

R/L Random lengths

R/W Random widths

R/W&L Random widths and lengths

Sdg Siding

Sel Select

S&E Side and Edge (surfaced on)

SE Sdg Square edge siding

SE & S Square edge and sound

S/L or S/LAP Shiplap

SL&C Shipper's load and count

SM or Std M Standard matched

Specs Specifications

Std Standard

Stpg Stepping

Str or Struc Structural

S1E Surfaced one edge

S1S Surfaced one side

S1S1E Surfaced one side and one edge

S1S2E Surfaced one side and two edges

S2E Surfaced two edges

S2S Surfaced two sides

S2S1E Surfaced two sides and one edge

S2S&CM Surfaced two sides and center matched

S2S&SM Surfaced two sides and standard matched

S4S Surfaced four sides

S4S&CS Surfaced four sides and caulking seam

T&G Tongued and grooved

VG Vertical grain

Wdr Wider

Wt Weight
47

APPENDIX D IMPLEMENTATION AND MAINTENANCE OF STANDARD

D1. STANDING COMMITTEE

The American Lumber Standard Committee 

(ALSC) acts as the Standing Committee for this

Standard for the purpose of its interpretation 

and for considering future proposals for

amendments and revisions. Members of the 

ALSC and their alternates are appointed by the 

Secretary of Commerce in accordance with 

Section 9 of this Standard. The names of the 

members are available from the Committee's 

secretariat: Standards Services Division, 

National Institute of Standards and Technology, 

Gaithersburg, Maryland 20899-2100. Comments 

regarding the Standard and suggestions for its 

amendment or revision may also be sent to this 

address. No product shall be advertised or 

represented in any manner that would imply 

approval or endorsement of that product by the 

National Institute of Standards and Technology 

and/or the Department of Commerce.

D2. EFFECTIVE DATE

Voluntary Product Standard PS 20-20 Revision 

1, American Softwood Lumber Standard, a 

voluntary standard developed under the 

Department of Commerce procedures, shall be 

effective October 2021 for products produced 

thereunder on and after that date. The Standard 

being superseded, American Softwood Lumber 

Standard PS 20-20, is effective for products 

produced thereunder through October, 2021.

D3. HISTORY OF THE STANDARD

Early in 1922 Secretary of Commerce Herbert 

Hoover, responding to a request from the lumber 

industry, offered the cooperation of the 

Department in activities directed toward 

simplification, standardization, and development 

of adequate quality guarantees for the lumberconsuming public. This cooperation led to the

development and publication in 1924 of 

Simplified Practice Recommendation R 16 under 

the guidance of the Department's Division of 

Simplified Practices, which was to become a part 

of the National Bureau of Standards (now the 

National Institute of Standards and 

Technology). The history of R 16's development 

and its subsequent revisions is summarized in 

editions issued, respectively, in 1924, 1925, 

1926, 1929, 1939, and 1953.

R 16-53 was revised in 1969 and superseded by 

Voluntary Product Standard PS 20-70 American 

Softwood Lumber Standard. The significant 

provisions added to PS 20-70 were: 1) separate 

size standards for dry and green lumber, under 

nominal 5-inch thickness, were established in 

order to achieve greater uniformity in the 

dimensions of seasoned and unseasoned lumber 

at the point of use; 2) an independent National 

Grading Rule Committee was created to 

establish and maintain a national grading rule 

for dimension lumber conforming to PS 20; 3) an 

independent Board of Review was formed to 

assure uniform approval of grading rules and of 

agencies to grade under these rules, and to 

enhance enforcement of the accreditation 

program ; 4) the composition of the American 

Lumber Standard Committee was expanded to 

reflect a broader representation of interests; and

5) uniform methods for assignment of design 

values were accepted. Non-substantive changes 

were made to the Standard in 1985, 1991, 1992,

1999, 2005, 2010, and 2015. The Standard was 

reviewed in 2019 to assure it reflected the needs 

of manufacturers, distributors and consumers.

D4. CURRENT EDITION

The current edition, PS 20-20, has the same 

technical requirements and administrative 

structure for implementing and enforcing the 

Standard as its previous edition. This new 

edition was based on the recommendations 

resulting from an extensive technical and 

editorial review of PS 20-15 conducted by the 

Standing Committee with the assistance from 

the National Institute of Standards and 

Technology in 2019.