ASTM D245-22

Standard Practice for Establishing Structural Grades and Related Allowable Properties for Visually Graded Lumber

SIGNIFICANCE AND USE
3.1 Need for Lumber Grading:  
3.1.1 Individual pieces of lumber, as they come from the saw, represent a wide range in quality and appearance with respect to freedom from knots, cross grain, shakes, and other characteristics. Such random pieces likewise represent a wide range in strength, utility, serviceability, and value. One of the obvious requirements for the orderly marketing of lumber is the establishment of grades that permit the procurement of any required quality of lumber in any desired quantity. Maximum economy of material is obtained when the range of quality-determining characteristics in a grade is limited and all pieces are utilized to their full potential. Many of the grades are established on the basis of appearance and physical characteristics of the piece, but without regard for mechanical properties. Other grades, called structural or stress grades, are established on the basis of features that relate to mechanical properties. The latter designate near-minimum strength and near-average stiffness properties on which to base structural design.  
3.1.2 The development of this practice is based on extensive research covering tests of small clear specimens and of full-sized structural members. Detailed studies have included the strength and variability of clear wood, and the effect on strength from various factors such as density, knots (See Terminology D9), and other defects, seasoning, duration of stress, and temperature.  
3.2 How Visual Grading is Accomplished—Visual grading is accomplished from an examination of all four faces and the ends of the piece, in which the location as well as the size and nature of the knots and other features appearing on the surfaces are evaluated over the entire length. Basic principles of structural grading have been established that permit the evaluation of any piece of stress-graded lumber in terms of a strength ratio for each property being evaluated. The strength ratio of stress-graded lumber is the hypothet...
SCOPE
1.1 This practice (1, 2)2 covers the basic principles for establishing related unit stresses and stiffness values for design with visually-graded solid sawn structural lumber. This practice starts with property values from clear wood specimens and includes necessary procedures for the formulation of structural grades of any desired strength ratio.  
1.2 The grading provisions used as illustrations herein are not intended to establish grades for purchase, but rather to show how stress-grading principles are applied. Detailed grading rules for commercial stress grades which serve as purchase specifications are established and published by agencies which formulate and maintain such rules and operate inspection facilities covering the various species.  
1.3 The material covered in this practice appears in the following order:    
Section  
Scope  
1  
Significance and Use  
3  
Basic Principles of Strength Ratios  
4  
Estimation and Limitation of Growth Characteristics  
5  
Allowable Properties for Timber Design  
6  
Modification of Allowable Properties for Design Use  
7  
Example of Stress-Grade Development  
8  
1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trad...

General Information

• Status: Published
• Publication Date: 31-Jan-2022
• ICS: 79.040 - Wood, sawlogs and sawn timber
• Technical Committee: D07 - Wood
• Drafting Committee: D07.02 - Lumber and Engineered Wood Products

Relations

• Refers: ASTM D2555-17a(2024) - Standard Practice for Establishing Clear Wood Strength Values
• Effective Date: 01-Feb-2024
• Refers: ASTM D2555-17a(2024)e1 - Standard Practice for Establishing Clear Wood Strength Values
• Effective Date: 01-Feb-2024
• Refers: ASTM D143-23 - Standard Test Methods for Small Clear Specimens of Timber
• Effective Date: 15-Nov-2023
• Refers: ASTM D2555-17a - Standard Practice for Establishing Clear Wood Strength Values
• Effective Date: 01-Aug-2017
• Refers: ASTM D2555-17 - Standard Practice for Establishing Clear Wood Strength Values
• Effective Date: 15-Apr-2017
• Refers: ASTM D2555-16 - Standard Practice for Establishing Clear Wood Strength Values
• Effective Date: 01-Aug-2016
• Refers: ASTM D2555-15 - Standard Practice for Establishing Clear Wood Strength Values
• Effective Date: 01-Sep-2015
• Refers: ASTM D9-12 - Standard Terminology Relating to Wood and Wood-Based Products
• Effective Date: 15-Oct-2012
• Refers: ASTM D2555-06(2011) - Standard Practice for Establishing Clear Wood Strength Values
• Effective Date: 01-Oct-2011
• Refers: ASTM E105-10 - Standard Practice for Probability Sampling Of Materials
• Effective Date: 01-Oct-2010
• Refers: ASTM D9-09ae1 - Standard Terminology Relating to Wood and Wood-Based Products
• Effective Date: 15-Nov-2009
• Refers: ASTM D9-09a - Standard Terminology Relating to Wood and Wood-Based Products
• Effective Date: 15-Nov-2009
• Refers: ASTM D143-09 - Standard Test Methods for Small Clear Specimens of Timber
• Effective Date: 01-Sep-2009
• Refers: ASTM D9-09 - Standard Terminology Relating to Wood and Wood-Based Products
• Effective Date: 01-May-2009
• Refers: ASTM D143-94(2000)e1 - Standard Test Methods for Small Clear Specimens of Timber
• Effective Date: 10-Apr-2007

Overview

ASTM D245-22: Standard Practice for Establishing Structural Grades and Related Allowable Properties for Visually Graded Lumber provides a foundational methodology for defining structural grades and allowable mechanical properties of solid sawn lumber, based on visual grading. Developed by ASTM Committee D07, this standard emphasizes consistent evaluation and classification of lumber quality, allowing for reliable performance in construction and structural applications. It guides agencies and manufacturers in assessing the visual features of lumber-such as knots, grain slope, and other defects-that directly impact strength and serviceability.

Key Topics

• Need for Lumber Grading:

  • Lumber, as it comes from the sawmill, displays a broad range in quality and appearance related to knots, cross grain, shakes, and more.
  • Visual grading enables the selection of lumber with predictable characteristics, maximizing both structural performance and economic use.

• Principles of Visual Grading:

  • All four faces and ends of each piece are visually examined.
  • Features such as size, location, and nature of knots, slope of grain, shakes, checks, and splits are evaluated across the length of lumber.
  • Grades are assigned based on structural criteria related to mechanical properties, specifically strength and stiffness.

• Strength Ratios:

  • The concept of a "strength ratio" is central to this standard. Each defect is analyzed in terms of its impact on the lumber’s strength when compared to defect-free, “clear wood.”
  • Strength ratios inform the allowable stresses for critical properties such as bending, tension, and compression.

• Classification of Stress-Graded Lumber:

  • Includes dimension lumber (for framing), beams and stringers, posts and timbers, and stress-rated boards-each class is evaluated according to intended structural use.
  • Permissible characteristics are defined for each class, ensuring that the physical and mechanical properties match end-use requirements.

Applications

ASTM D245-22 is essential for professionals involved in wood construction, structural engineering, building design, and lumber manufacturing. Practical applications include:

• Design of Wooden Structures:
  • Engineers use the established structural grades and allowable properties for safe, efficient design of beams, joists, studs, and other load-bearing elements.
• Lumber Procurement:
  • Lumber suppliers and buyers reference these grades to ensure specified quality, performance, and code compliance for building projects.
• Building Codes and Inspection:
  • Inspectors and regulatory agencies rely on standardized grading to verify that construction materials meet safety standards.
• Development of Commercial Grading Rules:
  • Grading agencies base their commercial rules and purchase specifications on principles outlined in this standard.

Related Standards

Professionals using ASTM D245-22 often reference the following related standards for comprehensive compliance and quality assurance:

• ASTM D9 – Terminology Relating to Wood and Wood-Based Products
• ASTM D143 – Test Methods for Small Clear Specimens of Timber
• ASTM D2555 – Practice for Establishing Clear Wood Strength Values
• IEEE/ASTM SI-10 – Practice for Use of the International System of Units (SI)
• ASTM E105 – Guide for Probability Sampling of Materials

Conclusion

ASTM D245-22 plays a critical role in the wood products industry by standardizing the evaluation and classification of visually graded lumber. Through its clear criteria for visual grading and the establishment of strength-related properties, it ensures structural integrity and economic value in wood construction projects, supporting safety and reliability in diverse building applications. Employing this standard allows for confident material selection, code compliance, and long-term performance of wood structures.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D245 − 22
Standard Practice for
Establishing Structural Grades and Related Allowable
Properties for Visually Graded Lumber
This standard is issued under the fixed designation D245; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 1.6 This international standard was developed in accor-
2 dance with internationally recognized principles on standard-
1.1 This practice (1, 2) covers the basic principles for
ization established in the Decision on Principles for the
establishing related unit stresses and stiffness values for design
Development of International Standards, Guides and Recom-
with visually-graded solid sawn structural lumber. This prac-
mendations issued by the World Trade Organization Technical
tice starts with property values from clear wood specimens and
Barriers to Trade (TBT) Committee.
includes necessary procedures for the formulation of structural
grades of any desired strength ratio.
2. Referenced Documents
1.2 The grading provisions used as illustrations herein are 3
2.1 ASTM Standards:
not intended to establish grades for purchase, but rather to
D9 Terminology Relating to Wood and Wood-Based Prod-
show how stress-grading principles are applied. Detailed grad-
ucts
ing rules for commercial stress grades which serve as purchase
D143 Test Methods for Small Clear Specimens of Timber
specifications are established and published by agencies which
D2555 PracticeforEstablishingClearWoodStrengthValues
formulate and maintain such rules and operate inspection
E105 Guide for Probability Sampling of Materials
facilities covering the various species.
IEEE/ASTM SI-10 Practice for Use of the International
System of Units (SI) (the Modernized Metric System)
1.3 The material covered in this practice appears in the
following order:
3. Significance and Use
Section
Scope 1
3.1 Need for Lumber Grading:
Significance and Use 3
3.1.1 Individual pieces of lumber, as they come from the
Basic Principles of Strength Ratios 4
saw, represent a wide range in quality and appearance with
Estimation and Limitation of Growth Characteristics 5
Allowable Properties for Timber Design 6
respect to freedom from knots, cross grain, shakes, and other
Modification of Allowable Properties for Design Use 7
characteristics. Such random pieces likewise represent a wide
Example of Stress-Grade Development 8
range in strength, utility, serviceability, and value. One of the
1.4 The values stated in inch-pound units are to be regarded
obvious requirements for the orderly marketing of lumber is
as standard. The values given in parentheses are mathematical
the establishment of grades that permit the procurement of any
conversions to SI units that are provided for information only
required quality of lumber in any desired quantity. Maximum
and are not considered standard.
economy of material is obtained when the range of quality-
1.5 This standard does not purport to address all of the
determining characteristics in a grade is limited and all pieces
safety concerns, if any, associated with its use. It is the
are utilized to their full potential. Many of the grades are
responsibility of the user of this standard to establish appro-
established on the basis of appearance and physical character-
priate safety, health, and environmental practices and deter-
istics of the piece, but without regard for mechanical proper-
mine the applicability of regulatory limitations prior to use.
ties. Other grades, called structural or stress grades, are
established on the basis of features that relate to mechanical
properties. The latter designate near-minimum strength and
near-average stiffness properties on which to base structural
This practice is under the jurisdiction of ASTM Committee D07 on Wood and
is the direct responsibility of Subcommittee D07.02 on Lumber and Engineered
design.
Wood Products.
Current edition approved Feb. 1, 2022. Published March 2022. Originally
approved in 1926. Last previous edition approved in 2019 as D245–06(2019). DOI: For referenced ASTM standards, visit the ASTM website, www.astm.org, or
10.1520/D0245-22. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
The boldface numbers in parentheses refer to references at the end of this Standards volume information, refer to the standard’s Document Summary page on
practice. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D245 − 22
3.1.2 Thedevelopmentofthispracticeisbasedonextensive classes of stress-graded lumber, whether graded primarily for
research covering tests of small clear specimens and of that property or not. Recommendations for allowable proper-
full-sized structural members. Detailed studies have included ties may include all properties for all grades or use classes.
the strength and variability of clear wood, and the effect on While such universal application may result in loss of effi-
strength from various factors such as density, knots (See ciency in some particulars, it offers the advantage of a more
Terminology D9), and other defects, seasoning, duration of simple system of grades of stress-graded lumber.
stress, and temperature.
3.4 Essential Elements in a Stress-Grade Description:
3.4.1 Astress grade formulated by this practice contains the
3.2 How Visual Grading is Accomplished— Visual grading
following essential elements:
is accomplished from an examination of all four faces and the
3.4.2 Agrade name that identifies the use-class as described
ends of the piece, in which the location as well as the size and
in 3.3.
natureoftheknotsandotherfeaturesappearingonthesurfaces
3.4.3 A description of permissible growth characteristics
are evaluated over the entire length. Basic principles of
that affect mechanical properties. Characteristics that do not
structural grading have been established that permit the evalu-
affect mechanical properties may also be included.
ation of any piece of stress-graded lumber in terms of a
3.4.4 One or more allowable properties for the grade related
strength ratio for each property being evaluated. The strength
to its strength ratio.
ratio of stress-graded lumber is the hypothetical ratio of the
strength property being considered compared to that for the
4. Basic Principles of Strength Ratios
material with no strength-reducing characteristic. Thus a piece
of stress-graded lumber with a strength ratio of 75 % in
4.1 General Considerations:
bending would be expected to have 75 % of the bending
4.1.1 Strength ratios associated with knots in bending mem-
strength of the clear piece. In effect, the strength ratio system
bers have been derived as the ratio of moment-carrying
of visual structural grading is thus designed to permit practi-
capacity of a member with cross section reduced by the largest
cally unlimited choice in establishing grades of any desired
knot to the moment-carrying capacity of the member without
quality to best meet production and utilization requirements.
defect.This gives the anticipated reduction in bending strength
due to the knot. For simplicity, all knots on the wide face are
3.3 Classification of Stress-Graded Lumber:
treated as being either knots along the edge of the piece (edge
3.3.1 The various factors affecting strength, such as knots,
knots) or knots along the centerline of the piece (centerline
deviations of grain, shakes, and checks, differ in their effect,
knots).
depending on the kind of loading and stress to which the piece
4.1.2 Strength ratios associated with slope of grain in
is subjected. Stress-graded lumber is often classified according
bending members, and in members subjected to compression
to its size and use. Four classes are widely used, as follows:
parallel to grain, were obtained, experimentally (3).
3.3.1.1 Dimension Lumber—Pieces of rectangular cross
4.1.3 Strength ratios associated with shakes, checks, and
section, from nominal 2 to 4 in. thick and 2 or more in. wide,
splits are assumed to affect only horizontal shear in bending
graded primarily for strength in bending edgewise or flatwise,
members. These strength ratios were derived, as for knots, by
but also frequently used where tensile or compressive strength
assuming that a critical cross section is reduced by the amount
is important. Dimension lumber covers many sizes and end
of the shake, or by an equivalent split or check.
uses.Lumbergradedforspecificendusesmaydictateaspecial
4.1.4 Strength ratios associated with knots in compression
emphasis in grading and require an identifying grade name.
members have been derived as the ratio of load-carrying
NOTE 1—For example, in NorthAmerican grading under theAmerican
capacity of a member with cross section reduced by the largest
Lumber Standards Committee, stress graded dimension lumber categories
knot to the load-carrying capacity of the member without
that reflect end use include Light Framing, Structural Light Framing,
defect. No assumption of combined compression and bending
Structural Joists and Planks, and Studs.
is made.
3.3.1.2 Beams and Stringers—Pieces of rectangular cross
4.1.5 Tensile strength of lumber has been related to bending
section, 5 in. nominal and thicker, nominal width more than 2
strength and bending strength ratio from experimental results
in. greater than nominal thickness, graded for strength in
(4).
bending when loaded on the narrow face.
4.1.6 Strength in compression perpendicular to grain is little
3.3.1.3 Posts and Timbers—Pieces of square or nearly
affected in lumber by strength-reducing characteristics, and
squarecrosssection,5by5in.,nominaldimensionsandlarger,
strength ratios of 100 % are assumed for all grades.
nominal width not more than 2 in. greater than nominal
4.1.7 Modulus of elasticity of a piece of lumber is known to
thickness, graded primarily for use as posts or columns.
be only approximately related to bending strength ratio. In this
3.3.1.4 Stress-Rated Boards—Lumber less than 2 in. nomi-
standard, the relationship between full-span, edgewise bending
nal in thickness and 2 in. or wider nominal width, graded
modulus of elasticity and strength ratio was obtained experi-
primarily for mechanical properties.
mentally.
3.3.2 The assignment of names indicating the uses for the 4.1.8 In developing a stress-grade rule, economy may be
various classes of stress-graded lumber does not preclude their served by specifying strength ratios such that the allowable
use for other purposes. For example, posts and timbers may stresses for shear and for extreme fiber in bending will be in
give service as beams. The principles of stress grading permit balance, under the loading for which the members are de-
theassignmentofanykindofallowablepropertiestoanyofthe signed.
D245 − 22
4.1.9 A strength ratio can also be associated with specific 4.2.5 Strength ratios in tension parallel to grain are 55 % of
gravity. Three selection classes called dense, close grain, and the corresponding bending strength ratios.
medium grain are described herein, based on experimental 4.2.6 Table 6 gives strength ratios and quality factors for the
findings (5). special specific gravity classes described in 4.1.9.
4.2 Strength Ratios:
5. Estimation and Limitation of Growth Characteristics
4.2.1 Table 1 gives strength ratios, corresponding to various
5.1 General Quality of Lumber:
slopes of grain for stress in bending and compression parallel
5.1.1 All lumber should be well manufactured.
to grain.
5.1.2 Only sound wood, free from any form of decay, shall
4.2.2 Strength ratios for various combinations of size and
be permitted, unless otherwise specified. Unsound knots and
location of knot and width of face are given in Table 2, Table
limited amounts of decay in its early stages are permitted in
3, and Table 4. Since interpolation is often required in the
some of the lower stress-rated grades of lumber intended for
development of grading rules, the use of formulas in Table 2,
light frame construction.
Table 3 and Table 4 is acceptable. These formulas are found in
5.1.3 In stress-grading, all four faces and the ends shall be
the Appendix.
considered.
4.2.2.1 Use of the tables is illustrated by the following
1 1
example:Thesizesofknotspermittedina7 ⁄2by15 ⁄2-in.(190
5.2 Slope of Grain:
by 394 mm) (actual) beam in a grade having a strength ratio of
5.2.1 Slope of grain resulting from either diagonal sawing
70 % in bending are desired. The smallest ratio in the column
or from spiral or twisted grain in the tree is measured by the
fora7 ⁄2-in. (190 mm) face in Table 2 that equals or exceeds
angle between the direction of the fibers and the edge of the
70 % is opposite 2 ⁄8 in. (54 mm) in the size-of-knot column.A
piece. The angle is expressed as a slope. For instance, a slope
similar ratio in the column for 15 ⁄2-in. (394 mm) face in Table
of grain of 1 in 15 means that the grain deviates 1 in. (25 mm)
3isopposite4 ⁄4in.(108mm).Hence,thepermissiblesizesare
from the edge in 15 in. (381 mm) of length.
1 1
2 ⁄8 in. (54 mm) on the 7 ⁄2-in. (190 mm) face and at the edge
5.2.2 When both diagonal and spiral grain are present, the
of the wide face (see 5.3.5.2) and 4 ⁄4 in. (108 mm) on the
combined slope of grain is taken as the effective slope.
centerline of the 15 ⁄2-in. (394 mm) face.
5.2.3 Slope of grain is measured and limited at the zone in
4.2.3 For all lumber thicknesses, a strength ratio of 50 %
the length of a structural timber that shows the greatest slope.
shall be used for all sizes of shakes, checks and splits.A50 %
It shall be measured over a distance sufficiently great to define
strength ratio is the maximum effect a shake, check or split can
the general slope, disregarding such short local deviations as
have on the load-carrying capacity of a bending member.
those around knots except as indicated in 5.2.5.
Limitations in grading rules placed on the characteristics at
5.2.4 In 1-in. nominal boards (See Terminology D9), or
time of manufacture are for appearance and general utility
similar small sizes of lumber, a general slope of grain any-
purposes, and these characteristics shall not be used as a basis
where in the length shall not pass completely through the
for increasing lumber shear design values.
thickness of the piece in a longitudinal distance in inches less
than the number expressing the specified permissible slope.
NOTE 2—The factor of 0.5 (50 %) is not strictly a “strength ratio” for
Where such a slope varies across the width of the board, its
horizontal shear, since the factor represents more than just the effects of
shakes,checksandsplits.Thefactoralsoincludesdifferencesbetweentest
average may be taken.
values obtained in Test Methods D143 shear block tests and full-size
5.2.5 Local deviations must be considered in small sizes,
solid-sawn beam shear tests.The strength ratio terminology is retained for
andifalocaldeviationoccursinapiecelessthan4in.nominal
compatibility with prior versions of this practice, but prior provisions
inwidthoronthenarrowfaceofapiecelessthan2in.nominal
permittingdesignincreasesformemberswithlesser-sizecrackshavebeen
deleted since the factor is related to more than shakes, checks and splits. in thickness, and is not associated with a permissible knot in
the piece, the measurement of slope shall include the local
4.2.4 Modulus of elasticity is modified by a quality factor
deviation.
that is related to bending strength ratio, as given in Table 5.
5.3 Knots:
5.3.1 Aknot cluster is treated as an individual knot. Two or
more knots closely spaced, with the fibers deflected around
TABLE 1 Strength Ratios Corresponding to Various Slopes of
each knot individually, are not a cluster.
Grain
5.3.2 Holes associated with knots are measured and limited
Maximum Strength Ratio, %
in the same way as knots.
Bending or Compression
Slope of Grain 5.3.3 A knot on the wide face of a bending or tension
Tension Parallel Parallel
member is considered to be at the edge of the wide face if the
to Grain to Grain
center of the knot lies within two thirds of the knot diameter
1in6 40 56
1in8 53 66 from the edge.
1in10 61 74
5.3.4 Knots in Dimension Lumber:
1in12 69 82
5.3.4.1 Knots in dimension lumber may be measured by
1in14 74 87
1in15 76 100 displacement method, in which the proportion of the cross
1in16 80 .
sectionoftheknottothecrosssectionofthepieceismultiplied
1in18 85 .
by actual face width to establish the equivalent knot size (see
1in20 100 .
Fig. 1). This value is used in the strength ratio tables.
D245 − 22
TABLE 2 Strength Ratios Corresponding to Knots in the Narrow Face of Bending Members
A
Knot Percentage Strength Ratio When Actual Width of Narrow Face, in. (mm), is
Size, in.
1 1 1 1 1 1 1 1 1 1
1 1 ⁄2 2 2 ⁄2 3 3 ⁄2 4 4 ⁄2 5 5 ⁄2 6 7 7 ⁄2 8 9 9 ⁄2 10 11 11 ⁄2 12 13 13 ⁄2 14 15 15 ⁄2 16
A
(mm)
(25) (38) (51) (64) (76) (89) (102) (114) (127) (140) (152) (178) (190) (203) (229) (241) (254) (279) (292) (305) (330) (343) (356) (381) (394) (406)
⁄4(6) 8589919394959596969697979797979797979898989898989898
⁄2 (13) 67 76 81 84 86 88 90 91 91 92 93 93 93 94 94 94 94 94 95 95 95 95 95 95 95 95
⁄4 (19) 48 62 70 75 79 82 84 85 87 88 89 89 90 90 91 91 91 91 92 92 92 92 92 93 93 93
1(25) 449606872757880828485868687878888888989899090909090
1 ⁄4 (32) . . 49 58 64 69 72 75 78 79 81 82 83 83 84 84 85 85 86 86 87 87 87 87 88 88
1 ⁄2 (38) . . 27 49 57 62 67 70 73 75 77 78 79 80 81 81 82 82 83 83 84 84 84 85 85 85
1 ⁄4 (44) . . 15 32 49 56 61 65 68 71 73 75 75 76 77 78 78 79 80 80 81 81 82 82 83 83
2 (51) . . . 22 35 49 55 60 64 67 69 71 72 73 74 75 75 76 77 77 78 79 79 80 80 80
2 ⁄4 (57) . . . . 26 37 50 55 59 62 65 67 68 69 71 71 72 73 74 75 75 76 76 77 77 78
2 ⁄2 (64) . . . . 18 30 39 50 54 58 61 63 64 66 67 68 69 70 71 72 73 73 74 75 75 75
2 ⁄4 (70) . . . . . 23 32 40 50 54 57 60 61 62 64 65 66 67 68 69 70 70 71 72 72 73
3 (76) . . . . . . 26 34 41 50 53 56 57 59 61 62 63 64 65 66 67 68 68 69 70 70
3 ⁄4 (83) . . . . . . . . 36 45 49 52 54 55 57 59 60 61 62 63 64 65 66 67 67 68
3 ⁄2 (89) . . . . . . . . . 37 46 48 50 52 54 55 56 58 59 60 62 62 63 64 65 65
3 ⁄4 (95) . . . . . . . . . . . 45 46 48 51 52 53 55 56 57 59 60 60 61 62 63
4 (102) . . . . . . . . . . . . . 45 48 49 50 52 53 54 56 57 58 59 60 60
4 ⁄4 (108) . . . . . . . . . . . . . . . 46 47 49 50 51 53 54 55 56 57 58
4 ⁄2 (114) . . . . . . . . . . . . . . . . . 46 47 49 50 51 52 54 55 55
4 ⁄4 (121) . . . . . . . . . . . . . . . . . . . 46 48 49 50 51 52 53
5 (127) . . . . . . . . . . . . . . . . . . . . 45 46 47 49 49 50
A
Ratios corresponding to other sizes of knots and face widths can be found by linear interpolation.

D245 − 22
TABLE 3 Strength Ratios Corresponding to Centerline Knots in the Wide Face of Bending Members, and to Knots in Compression Members
A
Size of Percentage Strength Ratio When Actual Width of Wide Face, in. (mm), is
Knot, in.
1 1 1 1 1 1 1 1
3 3 ⁄2 4 4 ⁄2 5 5 ⁄2 6 7 7 ⁄2 8 9 9 ⁄2 10 11 11 ⁄2 12 13 13 ⁄2 14 15 15 ⁄2 16 18 20 22 24
A
(mm)
(76) (89) (102) (114) (127) (140) (152) (178) (190) (203) (229) (241) (254) (279) (292) (302) (330) (343) (356) (381) (394) (406) (457) (508) (559) (610)
⁄4(6) 9495959696969797979798989898989898989898989999999999
⁄2 (13) 86 88 90 91 91 92 93 94 94 95 95 95 96 96 96 96 96 96 97 97 97 97 97 97 97 97
⁄4 (19) 79 82 84 85 87 88 89 91 91 92 92 93 93 94 94 94 94 95 95 95 95 95 95 95 96 96
1 (25) 72 75 78 80 82 84 85 87 88 89 90 90 91 92 92 92 92 93 93 93 93 93 94 94 94 94
1 ⁄4 (32) 64 69 72 75 78 79 81 84 85 86 87 88 89 90 90 90 90 91 91 91 91 91 92 92 93 93
1 ⁄2 (38) 57 62 67 70 73 75 78 81 82 83 85 85 86 87 88 88 89 89 89 89 90 90 90 91 91 91
1 ⁄4 (44) 49 56 61 65 68 71 74 77 79 80 82 83 84 85 86 86 87 87 87 87 88 88 89 89 90 90
2 (51) 35 49 55 60 64 67 70 74 76 77 79 80 81 83 84 84 85 85 85 86 86 86 87 88 88 89
2 ⁄4 (57) 26 37 50 55 59 62 66 71 72 73 77 78 79 81 82 82 83 83 83 84 84 84 85 86 87 87
2 ⁄2 (64) 18 30 39 50 54 58 62 67 69 71 74 75 77 79 80 80 81 81 81 82 82 83 84 84 85 86
2 ⁄4 (70) . 23 32 40 50 54 58 64 66 68 71 73 74 76 77 78 79 79 79 80 80 81 82 83 84 84
3 (76) . . 26 34 41 50 54 61 63 65 69 70 72 74 75 76 77 77 78 78 79 79 80 81 82 83
3 ⁄4 (83) . . . 29 36 45 51 57 60 62 66 68 69 72 73 74 75 75 76 76 77 77 78 80 80 81
3 ⁄2 (89) . . . 23 31 37 47 54 57 59 64 65 67 70 71 72 73 73 74 75 75 75 77 78 79 80
3 ⁄4 (95) . . . . 26 32 38 51 54 56 61 63 65 68 69 70 71 71 72 73 73 74 75 76 77 78
4 (102) . . . . 21 28 34 47 50 53 58 60 62 66 67 68 69 69 70 71 71 72 73 75 76 77
4 ⁄4 (108) . . . . . 23 30 40 46 50 56 58 60 63 65 66 67 68 68 69 70 70 72 73 74 75
4 ⁄2 (114) . . . . . 19 26 36 41 48 53 55 58 61 63 64 65 66 66 67 68 68 70 72 73 74
4 ⁄4 (121) . . . . . . 21 33 37 41 50 53 55 59 61 62 63 64 64 65 66 67 68 70 71 73
5 (127) . . . . . . 17 29 34 38 48 50 53 57 59 60 61 62 62 64 64 65 67 68 70 71
5 ⁄4 (133) . . . . . . . 25 30 35 45 48 50 55 57 58 59 60 61 62 62 63 65 67 68 70
5 ⁄2 (140) . . . . . . . 22 27 32 39 45 48 52 54 56 57 58 59 60 61 61 63 65 67 68
5 ⁄4 (146) . . . . . . . . 24 29 37 40 46 50 52 54 55 56 57 58 59 59 62 64 65 67
6 (152) . . . . . . . . . . . 26 34 37 40 48 50 52 53 54 55 56 57 58 60 62 64 65
6 ⁄2 (165) . . . . . . . . . 19 28 32 35 41 46 48 49 50 51 53 53 54 57 59 61 62
7 (178) . . . . . . . . . 13 23 27 30 37 40 42 45 46 47 49 50 51 53 56 58 59
7 ⁄2 (190) . . . . . . . . . . 17 22 25 32 35 38 40 41 42 45 46 47 50 52 55 57
8 (203) . . . . . . . . . . . . 20 28 31 34 36 37 39 41 42 43 47 49 52 54
8 ⁄2 (216) . . . . . . . . . . . . 15 23 26 30 32 33 35 37 38 39 41 46 49 51
A
Ratios corresponding to other sizes of knots and face widths can be found by linear interpolation.

D245 − 22
TABLE 4 Strength Ratios Corresponding to Edge Knots in the Wide Face of Bending Members
A
Knot Percentage Strength Ratio When Actual Width of Wide Face, in. (mm), is
Size, in.
1 1 1 1 1 1 1 1 1
2 2 ⁄2 3 3 ⁄2 4 4 ⁄2 5 5 ⁄2 6 7 7 ⁄2 8 9 9 ⁄2 10 11 11 ⁄2 12 13 13 ⁄2 14 15 15 ⁄2 16 18 20 22 24
A
(mm)
(51) (64) (76) (89) (102) (114) (127) (140) (152) (178) (190) (203) (229) (241) (254) (279) (292) (305) (330) (343) (356) (381) (394) (406) (457) (508) (559) (610)
⁄4(6) 83868889919192939494949595969696979797979797979797979798
⁄2 (13) 65 71 75 78 80 82 84 85 86 88 89 90 90 91 91 92 92 93 93 93 93 93 93 94 94 94 94 95
⁄4 (19) 49 57 62 67 70 73 75 77 79 82 83 84 86 86 87 88 89 89 89 89 90 90 90 90 91 91 92 92
1 (25) 27 38 51 57 61 65 68 70 73 76 77 79 81 82 83 84 85 85 85 86 86 86 87 87 88 88 89 89
1 ⁄4 (32) 16 27 36 47 52 57 60 63 66 71 72 74 76 77 78 80 81 82 82 82 83 83 83 84 84 85 86 86
1 ⁄2 (38) . 17 26 34 40 49 53 57 60 64 67 69 72 73 74 76 77 78 78 79 79 80 80 80 81 82 83 84
1 ⁄4 (44) . . 19 26 33 38 47 50 54 60 62 64 67 69 70 72 74 75 75 75 76 77 77 77 78 79 80 81
2 (51) . . . 19 26 32 37 45 49 55 57 59 63 65 66 69 70 71 72 72 73 73 74 74 75 77 78 78
2 ⁄4 (57) . . . . 20 26 31 36 40 50 52 55 59 61 62 65 66 68 68 69 69 70 71 71 73 74 75 76
2 ⁄2 (64) . . . . 15 21 26 31 35 45 48 51 55 57 59 62 63 65 65 66 66 67 68 68 70 71 72 73
2 ⁄4 (70) . . . . . 16 21 26 30 38 41 46 51 53 55 59 60 61 62 63 63 64 65 65 67 68 70 71
3 (76) . . . . . . 17 21 26 33 37 40 47 50 52 55 57 58 59 60 60 61 62 62 64 66 67 68
3 ⁄4 (83) . . . . . . . 17 22 29 32 36 41 46 48 52 54 55 56 57 57 58 59 60 62 63 65 66
3 ⁄2 (89) . . . . . . . . 18 26 29 32 39 41 43 49 52 52 53 54 54 56 56 56 59 61 62 63
3 ⁄4 (95) . . . . . . . . . 23 26 29 35 37 40 46 48 49 50 51 52 53 54 54 56 58 60 61
4 (102) . . . . . . . . . . 22 26 32 34 37 41 45 47 48 48 49 50 51 52 54 56 58 59
4 ⁄4 (108) . . . . . . . . . . . 22 28 31 34 38 40 42 44 45 46 48 48 49 51 54 55 57
4 ⁄2 (114) . . . . . . . . . . . 20 26 28 31 35 37 39 41 42 43 45 46 47 49 51 53 54
4 ⁄4 (121) . . . . . . . . . . . . 23 26 28 33 35 37 39 40 41 42 43 44 47 49 51 52
5 (127) . . . . . . . . . . . . . . . . 25 30 32 34 36 37 38 40 40 41 44 47 49 50
A
Ratios corresponding to other sizes of knots and face widths can be found by linear interpolation.

D245 − 22
TABLE 5 Quality Factors for Modulus of Elasticity
Quality Factor for
Bending Strength
Modulus of
Ratio, %
Elasticity, %
$55 100
45 to 54 90
#44 80
TABLE 6 Strength Ratios and Quality Factors for Special Specific
Gravity Classifications
Specific Gravity Classification, %
Property Close Medium
Dense
Grain Grain
Bending stress
Tensile stress parallel to grain
Compressive stress parallel to grain 117 107 100
Compressive stress perpendicular to
grain
Modulus of elasticity 105 100 100
FIG. 2 Measurement of Knots in Dimension Lumber Using Alter-
native Method
5.3.4.6 The sum of the sizes of all knots in any 6 in. (152
mm) of length of piece shall not exceed twice the size of the
largest permitted knot.Two or more knots of maximum or near
maximum permissible size shall not be allowed in the same 6
in. (152 mm) of length on a face. Any combination of knots
that, in the judgment of the lumber grader, will make the piece
unfit for its intended use, shall not be admitted.
FIG. 1 Measurement of Knots in Dimension Lumber Using Dis-
placement Method (Primary Method)
5.3.4.7 For sizes 3 by 3 in. nominal and smaller the effects
of grain distortion associated with knots can be so severe that
all knots shall be limited as if they were wide-face edge knots
5.3.4.2 Alternatively, knots in dimension lumber may be in the face on which they appear.
measured on the surface of the piece. Methods of measuring 5.3.4.8 Where the grade is intended to be used for single-
knots by this alternative are given in 5.3.4.3 – 5.3.4.5. span bending applications only, the sizes of knots on narrow
5.3.4.3 The size of a knot on a narrow face is its width faces and at the edge of wide faces may increase proportion-
between lines enclosing the knot and parallel to the edges of ately from the size permitted in the middle one third of the
the piece (Fig. 2). A narrow-face knot that appears also in the
length to twice that size at the ends of the piece, except that the
wide face of a side-cut piece (but does not contain the size of no knot shall exceed the size permitted at the center of
intersectionofthosefaces)ismeasuredandgradedonthewide the wide face. The size of knots on wide faces may be
face. increasedproportionatelyfromthesizepermittedattheedgeto
5.3.4.4 The size of a knot on a wide face is the average of the size permitted at the centerline (Fig. 3).
its largest and smallest dimensions (Fig. 2). 5.3.4.9 Where the grade is intended to be used on continu-
5.3.4.5 Any knot that contains the intersection of two faces, ous spans, the restrictions for knots in the middle one third of
including a knot extending entirely across the width of a face their lengths shall be applied to the middle two thirds of the
in a side-cut piece, is a corner knot.Acorner knot is measured length of pieces continuous on three supports, and to the full
on its end between lines parallel to the edges of the piece and length of pieces continuous on four or more supports.
is graded with respect to the face on which it is measured (Fig. 5.3.5 Knots in Beams and Stringers:
2). A corner knot in a piece containing the pith is measured 5.3.5.1 The size of a knot on a narrow face of a beam or
either by its width on the narrow face between lines parallel to stringer is its width between lines enclosing the knot and
the edge, or by its smallest diameter on the wide face, parallel to the edges of the piece (Fig. 4). When a knot on a
whichever is more restrictive (Fig. 2). If a corner knot appears narrow face of a side-cut piece extends into the adjacent one
also on an opposite face, its limitation there as well as on the fourth of the width of a wide face, it is measured on the wide
corner is necessary. face.
D245 − 22
A, maximum size on narrow face in middle third of length with a uniform increase to 2A but not to exceed B, at the ends.
B, maximum size at center of wide face.
C, maximum size at edge of wide face in middle third of length with a uniform increase to 2C but not to exceed B at the ends and a uniform increase to B at the center
of the wide face. In beams and stringers, A and C are equal.
L, length.
W, width of wide face.
T, width of narrow face.
FIG. 3 Maximum Size of Knots Permitted in Various Parts of Joists and Planks, and Beams and Stringers
5.3.5.6 Where the grade is intended to be used on continu-
ous spans, the restrictions for knots in the middle one third of
their lengths shall be applied to the middle two thirds of the
length of pieces continuous on three supports, and to the full
length of pieces continuous on four or more supports.
5.3.6 Knots in Posts and Timbers:
5.3.6.1 The size of a knot on any face of a post or timber is
taken as the diameter of a round knot, the lesser of the two
diameters of an oval knot, or the greatest diameter perpendicu-
lar to the length of a spike knot (Fig. 5).
5.3.6.2 A corner knot is measured wherever the measure-
ment will represent the true diameter of the branch causing the
FIG. 4 Measurement of Knots in Beams and Stringers
knot.
5.3.5.2 The size of a knot on the wide face is measured by
its smallest diameter (Fig. 4).An edge knot on the wide face is
limited to the same size as a knot on the narrow face.
5.3.5.3 A corner knot in a beam or stringer containing the
pithismeasuredeitherbyitswidthonthenarrowfacebetween
lines parallel to the edges or by its smallest diameter on the
wide face, whichever is greater (Fig. 4). A corner knot in a
side-cut piece is measured by whichever of these two is least.
5.3.5.4 The sum of the sizes of all knots within the middle
one half of the length of a face, in a beam 20 ft (6.1 m) or less
in length, when measured as specified for the face under
consideration,shallnotexceedfourtimesthesizeofthelargest
knot allowed on that face. This restriction in a beam longer
than 20 ft (6.1 m) shall apply to any 10 ft (3.0 m) of length
within the middle one half of the length.
5.3.5.5 Where the grade is used for single-span bending
applications only, the sizes of knots on narrow faces and at the
edges of wide faces may be increased proportionately from the
sizepermittedinthemiddleonethirdofthelengthtotwicethat
size at the ends of the piece, except that the size of no knot
shall exceed the size permitted at the center of the wide face.
The size of knots on wide faces may be increased proportion-
ately from the size permitted at the edge to the size permitted
FIG. 5 Measurement of Knots in Posts and Timbers or Other
at the center line (Fig. 3). Compression Members
D245 − 22
5.3.6.3 The sum of the sizes of all knots in any 6 in. (152 may be made. The size of the split, measured differently than
mm) of length of a post or timber shall not exceed twice the in 5.4.2, is its average length along the length of the piece.
size of the largest permitted knot. Two or more knots of 5.4.7 Provisions for shakes, checks, and splits as described
maximum or near maximum permissible size shall not be in 5.4.1 – 5.4.6 are applicable to boards if used where shear
allowed in the same 6 in. (152 mm) of length on a face. strength is important.
5.3.6.4 In compression members with greater width than
5.5 Waneispermissibleinallgradesofbendingmembersas
thickness, the sizes of knots in both the narrow and the wide
far as strength properties are concerned, but “free from wane”
faces are allowed up to the size permitted in the wide face.
may be specified when required by appearance, connections,
5.3.7 Knots in Stress-Rated Boards:
bearing, or other factors of use.
5.3.7.1 Knots in stress-rated nominal boards are measured
5.6 Specific Gravity Selection :
by the average of the widths on the two opposite faces, each
5.6.1 Lumber may be selected as dense by grain character-
width being taken between lines parallel to the edges of the
istics for Douglas-fir and southern pine. To be classified dense
board. Knots are not measured on the narrow face, since they
the wood shall average on one end or the other of each piece
appear also in one or both wide faces.
not less than six annual rings per inch (25 mm) and one third
5.3.7.2 The sum of the sizes of all knots in any 6 in. (152
or more summerwood (the darker, harder portion of the annual
mm) of length shall not exceed twice the size of the largest
ring) measured on a representative radial line. Pieces that
permitted knot. Two or more knots of maximum permissible
average not less than four annual rings per inch (25 mm) shall
size shall not be allowed in the same 6 in. (152 mm) of length
be accepted as dense if they average one half or more
on a face.
summerwood. The contrast in color between springwood and
5.4 Shakes, Checks, and Splits:
summerwood in either case shall be distinct.
5.4.1 Shakes are measured at the ends of the piece. The size 5.6.1.1 To ensure a representative radial line, measurement
ofashakeisthedistancebetweenlinesenclosingtheshakeand shall be made over a continuous length of 3 in. (76 mm) or as
parallel to the wide face of the piece. nearly 3 in. (76 mm) as is available. The length shall be
5.4.2 Splits and checks are treated as “equivalent shakes,” centrally located in side-cut pieces. In pieces containing the
pith, the measurement may exclude an inner portion of the
but are measured differently. The size of a side check is its
average depth of penetration into the piece, measured from and radius amounting to approximately one quarter of the least
dimension of the piece.
perpendicular to the surface of the wide face on which it
appears.The size of an end split or end check is one third of its 5.6.2 Dense material of any species may be selected by
methods other than described above, provided that such meth-
average length measured along the length of a piece, except as
noted in 5.4.6. ods ensure the increases in properties given in 4.2.6.
5.6.2.1 One test that may be used to determine whether the
5.4.3 In single-span bending members, shakes, checks, and
requirements of 5.6.2 are met relative to strength properties is
splits are restricted only for a distance from each end equal to
to show that:
three times the width of the wide face, and within the critical
zone, only in the middle one half of the wide face. For
2 2
=
1.17 EV % ~A1BG! 2 1.645 B ~s !1rms (1)
multiple-span bending members, shakes, checks, and splits are
restricted throughout the length in the middle one half of the where:
wide face.
EV = 5 % exclusion value of a strength property for
5.4.4 Outside the critical zone in bending members, and in
thespecies,asdescribedinTestMethodsD2555.
axially loaded members, shakes, checks, and splits have little
ornoeffectonstrengthpropertiesandarenotrestrictedforthat
A and B = regression coefficients of strength property ver-
reason. It may be advisable to limit them in some applications susspecificgravityforthespeciesgiveninTable
for appearance purposes, or to prevent moisture entry and
7,
G = average specific gravity (based on green volume
subsequent decay.
and ovendry weight) of the pieces selected as
5.4.5 The grading of any combination of shakes, checks,
dense by mechanical means,
and splits is based on the grader’s judgment of the probable
s = the standard deviation of specific gravity of the
effects of seasoning or loading in service on the combination.
pieces selected as dense by mechanical means,
Where a combination of two checks in opposite faces, a check
and
andasplit,acheckandashake,orasplitandashakemaylater
rms = residual mean square (the square of the standard
become a single horizontal shear plane, the sum of the sizes in
deviation about regression given in Table 7)
the combination is restricted to the allowable size of shakes.
associated with the regression for strength prop-
Where such a combination is not additive in this way, only the
erty versus specific gravity for the species.
largest single characteristic is considered.
5.4.6 Where 2-in. nominal dimension (See Terminology 5.6.2.2 One test that may be used to determine whether the
D9) is to be used in light building construction in which the requirements of 5.6.2 are met relative to modulus of elasticity
shearstressisnotcritical,amoreliberalprovisiononendsplits is to show that:
D245 − 22
TABLE 7 Regression Coefficients for Strength Properties Versus Specific Gravity
NOTE 1—These coefficients are extracted from Refs (6) and (7).
Properties
Compression Parallel to Grain, max Compression Perpendicular to
Modulus of Rupture Modulus of Elasticity Shear
crushing Grain
Species or Re-
Standard Standard Standard Standard Standard
gion or Both
Deviation Deviation Deviation Deviation Deviation
A A A A A A A A A A
A B A B A B A B A B
from from from from from
B B B B B
Regression Regression Regression Regression Regression
Douglas-fir
Coast −1757 20 894 572 −259 4036 216 −1087 10 803 403 193 1580 96 . . .
Interior west −1750 20 694 571 −408 4203 215 −1548 11 854 414 174 1669 98 . . .
Interior north −1396 19 783 635 −212 3631 208 −905 9797 360 184 1711 94 . . .
Interior south 25 15 679 576 151 2346 171 21 7174 369 18 2171 118 . . .
White fir −277 16 650 588 −226 3770 183 −854 10 200 265 306 1223 56 . . .
Cal. red fir 57 15 993 562 179 2759 240 −267 8411 286 287 1336 134 . . .
Grand fir 2516 9591 538 697 1650 148 991 5623 269 218 1505 72 . . .
Pacific silver fir −1861 21 086 447 109 3343 169 −568 9459 227 70 1725 56 . . .
Noble fir −1148 19 518 487 −588 5253 214 −1285 11 467 272 275 1408 122 . . .
Western hemlock −365 16 623 637 214 2597 218 −764 9804 329 221 1529 67 . . .
Western larch 1004 13 905 742 726 1534 237 −31 7921 414 294 1204 61 . . .
Black cottonwood 352 14 269 815 263 2580 176 484 5396 308 52 1761 69 . . .
Southern Pine
Loblolly −1318 18 287 717 −317 3648 258 −967 9501 354 224 1359 86 −150 1191 98
Longleaf −986 17 609 811 −281 3453 216 −466 8851 485 298 1365 91 −135 1124 133
Shortleaf 67 15 682 851 227 2472 237 −300 8141 383 −34 1999 73 24 644 101
Slash 47 16 152 551 198 2492 252 778 5690 423 391 1070 110 57 874 143
A
Coefficients in the relationY=A+BX where Y = mechanical property (in 1000 psi for MOE; in psi for all others) and X = specific gravity.
B
The standard deviation from regression is a measure of dispersion about the regression, representing the standard deviation of property about the line at any choice of specific gravity. This parameter is often called
the standard error of estimate. Units are in psi except MOE, which is in 1000 psi.

D245 − 22
¯
1.05 Y % A1BG (2)
nearest 50 psi (340 kPa) for allowable
where: Bending
stress of 1000 psi (6.9 MPa) or
Tension parallel to grain
¯
Y = average modulus of elasticity of the species, as greater
Compression parallel to grain 5
nearest 25 psi (170 kPa) otherwise
given in Test Methods D2555,
A and B = regression coefficients of modulus of elasticity
versus specific gravity for the species given in
Table 9, and
Horizontal shear
G = average specific gravity (based on green volume
Compression perpendicular nearest 5 psi (34 kPa)
and ovendry weight) of the pieces selected as
to grain
dense by mechanical means.
5.6.3 Lumber may be selected as close grain for Douglas-fir
Modulus of elasticity nearest 100 000 psi (69 GPa)
from the Coast Region, redwood, and southern pine. To be
The rounding rules of IEEE/ASTM SI-10, 4.2, shall be
classified as close grain the wood shall average on one end or
followed.
the other of each piece not less than 6 nor more than 30 annual
rings per inch (25 mm) measured on a representative radial
6.2 The 5 % exclusion limit for bending strength, tensile
line. To ensure a representative radial line, measurement shall strength parallel to grain, compressive strength parallel to
be made as in 5.6.1.1. Pieces averaging at least 5 or more than
grain, and horizontal shear strength for clear straight-grained
30 rings per inch shall be accepted as close-grained if the wood in the green condition shall be obtained for any species
measurement shows one third or more summerwood. Visually or group of species from Test Methods D2555. These proper-
selected close-grained redwood shall average in one piece not
ties when divided by the factors given in Table 8 give the
less than 8 nor more than 40 annual rings per inch. respective allowable design properties for clear straight-
5.6.4 Close-grainedwoodofanyspeciesmaybeselectedby
grained wood. The factors include an adjustment for normal
methods other than described above, provided that such meth- duration of load and a factor of safety.
ods ensure the increases in properties given in 4.2.6.
6.2.1 The average green modulus of elasticity, proportional
5.6.4.1 One test that may be used to determine whether the limit in compression perpendicular to grain, and stress in
requirements of 5.6.4 are met is to show that:
compression perpendicular to grain at 0.04-in. (1 mm) defor-
mation shall be obtained for any species or group of species
2 2
1.07 EV % ~A1BG! 2 1.645 =B ~s !1rms (3)
from Test Methods D2555. The properties shall be divided by
where the symbols have the meaning given in 5.6.2.1. the factors given in Table 8. The factor for modulus of
5.6.5 It is advisable to reject exceptionally lightweight
elasticity adjusts the modulus from a span-depth ratio of 14 to
pieces from the highest grades. For the softwoods with a span-depth ratio of 21 and an assumed uniform loading. The
pronounced summerwood, selection for medium grain serves
factor for the proportional limit stress in compression perpen-
this purpose. Medium-grained wood shall average on one end dicular to grain and for stress in compression perpendicular to
or the other of each piece not less than four annual rings per
grain at a deformation is an adjustment for the most limiting
inch (25 mm), measured on a representative radial line. To
ring position (8).
ensure a representative radial line, measurement shall be made
6.2.2 As an alternative to 6.2.1, the modulus of elasticity of
as in 5.6.1.1.
lumber grades may be determined by a comprehensive survey
of material in the finished condition of manufacture. The
6. Allowable Properties for Timber Design
objective of a survey is to measure with acceptable precision
6.1 Principles of Determination of Allowable Properties—
the average modulus of any grade or classification of lumber,
Test Methods D2555 provide information on clear wood
and should also provide detail on the variability of the
property values and their variation. From these values, allow-
modulus. Appropriate correlations for orientation in use and
able properties are obtained for green lumber, according to the
span-depth ratios shall be applied to the survey data. The
permitted growth characteristics as discussed in Sections 4 and
survey shall be representative of the entire output of the grade
5. The allowable properties are based on normal loading
duration, and the assumption that design loads are realistic and
that each member carries its own load. Allowable properties
TABLE 8 Adjustment Factors to Be Applied to the
can be determined for individual species or groups of species. Clear Wood Properties
The allowable modulus of
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D245 − 06 (Reapproved 2019) D245 − 22
Standard Practice for
Establishing Structural Grades and Related Allowable
Properties for Visually Graded Lumber
This standard is issued under the fixed designation D245; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope
1.1 This practice (1, 2) covers the basic principles for establishing related unit stresses and stiffness values for design with
visually-graded solid sawn structural lumber. This practice starts with property values from clear wood specimens and includes
necessary procedures for the formulation of structural grades of any desired strength ratio.
1.2 The grading provisions used as illustrations herein are not intended to establish grades for purchase, but rather to show how
stress-grading principles are applied. Detailed grading rules for commercial stress grades which serve as purchase specifications
are established and published by agencies which formulate and maintain such rules and operate inspection facilities covering the
various species.
1.3 The material covered in this practice appears in the following order:
Section
Scope 1
Significance and Use 3
Basic Principles of Strength Ratios 4
Estimation and Limitation of Growth Characteristics 5
Allowable Properties for Timber Design 6
Modification of Allowable Properties for Design Use 7
Example of Stress-Grade Development 8
1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information purposes only.only and are not considered standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
This practice is under the jurisdiction of ASTM Committee D07 on Wood and is the direct responsibility of Subcommittee D07.02 on Lumber and Engineered Wood
Products.
Current edition approved Oct. 1, 2019Feb. 1, 2022. Published November 2019March 2022. Originally approved in 1926. Last previous edition approved in 20112019 as
D245–06(2011).D245–06(2019). DOI: 10.1520/D0245-06R19.10.1520/D0245-22.
The boldface numbers in parentheses refer to references at the end of this practice.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D245 − 22
2. Referenced Documents
2.1 ASTM Standards:
D9 Terminology Relating to Wood and Wood-Based Products
D143 Test Methods for Small Clear Specimens of Timber
D2555 Practice for Establishing Clear Wood Strength Values
E105 Guide for Probability Sampling of Materials
IEEE/ASTM SI-10 Practice for Use of the International System of Units (SI) (the Modernized Metric System)
3. Significance and Use
3.1 Need for Lumber Grading:
3.1.1 Individual pieces of lumber, as they come from the saw, represent a wide range in quality and appearance with respect to
freedom from knots, cross grain, shakes, and other characteristics. Such random pieces likewise represent a wide range in strength,
utility, serviceability, and value. One of the obvious requirements for the orderly marketing of lumber is the establishment of grades
that permit the procurement of any required quality of lumber in any desired quantity. Maximum economy of material is obtained
when the range of quality-determining characteristics in a grade is limited and all pieces are utilized to their full potential. Many
of the grades are established on the basis of appearance and physical characteristics of the piece, but without regard for mechanical
properties. Other grades, called structural or stress grades, are established on the basis of features that relate to mechanical
properties. The latter designate near-minimum strength and near-average stiffness properties on which to base structural design.
3.1.2 The development of this practice is based on extensive research covering tests of small clear specimens and of full-sized
structural members. Detailed studies have included the strength and variability of clear wood, and the effect on strength from
various factors such as density, knots (See Terminology D9), and other defects, seasoning, duration of stress, and temperature.
3.2 How Visual Grading is Accomplished— Visual grading is accomplished from an examination of all four faces and the ends
of the piece, in which the location as well as the size and nature of the knots and other features appearing on the surfaces are
evaluated over the entire length. Basic principles of structural grading have been established that permit the evaluation of any piece
of stress-graded lumber in terms of a strength ratio for each property being evaluated. The strength ratio of stress-graded lumber
is the hypothetical ratio of the strength property being considered compared to that for the material with no strength-reducing
characteristic. Thus a piece of stress-graded lumber with a strength ratio of 75 % in bending would be expected to have 75 % of
the bending strength of the clear piece. In effect, the strength ratio system of visual structural grading is thus designed to permit
practically unlimited choice in establishing grades of any desired quality to best meet production and utilization requirements.
3.3 Classification of Stress-Graded Lumber:
3.3.1 The various factors affecting strength, such as knots, deviations of grain, shakes, and checks, differ in their effect, depending
on the kind of loading and stress to which the piece is subjected. Stress-graded lumber is often classified according to its size and
use. Four classes are widely used, as follows:
3.3.1.1 Dimension Lumber—Pieces of rectangular cross section, from nominal 2 to 4 in. thick and 2 or more in. wide, graded
primarily for strength in bending edgewise or flatwise, but also frequently used where tensile or compressive strength is important.
Dimension lumber covers many sizes and end uses. Lumber graded for specific end uses may dictate a special emphasis in grading
and require an identifying grade name.
NOTE 1—For example, in North American grading under the American Lumber Standards Committee, stress graded dimension lumber categories that
reflect end use include Light Framing, Structural Light Framing, Structural Joists and Planks, and Studs.
3.3.1.2 Beams and Stringers—Pieces of rectangular cross section, 5 in. nominal and thicker, nominal width more than 2 in. greater
than nominal thickness, graded for strength in bending when loaded on the narrow face.
3.3.1.3 Posts and Timbers—Pieces of square or nearly square cross section, 5 by 5 in., nominal dimensions and larger, nominal
width not more than 2 in. greater than nominal thickness, graded primarily for use as posts or columns.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
D245 − 22
3.3.1.4 Stress-Rated Boards—Lumber less than 2 in. nominal in thickness and 2 in. or wider nominal width, graded primarily for
mechanical properties.
3.3.2 The assignment of names indicating the uses for the various classes of stress-graded lumber does not preclude their use for
other purposes. For example, posts and timbers may give service as beams. The principles of stress grading permit the assignment
of any kind of allowable properties to any of the classes of stress-graded lumber, whether graded primarily for that property or not.
Recommendations for allowable properties may include all properties for all grades or use classes. While such universal
application may result in loss of efficiency in some particulars, it offers the advantage of a more simple system of grades of
stress-graded lumber.
3.4 Essential Elements in a Stress-Grade Description:
3.4.1 A stress grade formulated by this practice contains the following essential elements:
3.4.2 A grade name that identifies the use-class as described in 3.3.
3.4.3 A description of permissible growth characteristics that affect mechanical properties. Characteristics that do not affect
mechanical properties may also be included.
3.4.4 One or more allowable properties for the grade related to its strength ratio.
4. Basic Principles of Strength Ratios
4.1 General Considerations:
4.1.1 Strength ratios associated with knots in bending members have been derived as the ratio of moment-carrying capacity of a
member with cross section reduced by the largest knot to the moment-carrying capacity of the member without defect. This gives
the anticipated reduction in bending strength due to the knot. For simplicity, all knots on the wide face are treated as being either
knots along the edge of the piece (edge knots) or knots along the centerline of the piece (centerline knots).
4.1.2 Strength ratios associated with slope of grain in bending members, and in members subjected to compression parallel to
grain, were obtained, experimentally (3).
4.1.3 Strength ratios associated with shakes, checks, and splits are assumed to affect only horizontal shear in bending members.
These strength ratios were derived, as for knots, by assuming that a critical cross section is reduced by the amount of the shake,
or by an equivalent split or check.
4.1.4 Strength ratios associated with knots in compression members have been derived as the ratio of load-carrying capacity of
a member with cross section reduced by the largest knot to the load-carrying capacity of the member without defect. No assumption
of combined compression and bending is made.
4.1.5 Tensile strength of lumber has been related to bending strength and bending strength ratio from experimental results (4).
4.1.6 Strength in compression perpendicular to grain is little affected in lumber by strength-reducing characteristics, and strength
ratios of 100 % are assumed for all grades.
4.1.7 Modulus of elasticity of a piece of lumber is known to be only approximately related to bending strength ratio. In this
standard, the relationship between full-span, edgewise bending modulus of elasticity and strength ratio was obtained
experimentally.
4.1.8 In developing a stress-grade rule, economy may be served by specifying strength ratios such that the allowable stresses for
shear and for extreme fiber in bending will be in balance, under the loading for which the members are designed.
4.1.9 A strength ratio can also be associated with specific gravity. Three selection classes called dense, close grain, and medium
grain are described herein, based on experimental findings (5).
4.2 Strength Ratios:
D245 − 22
4.2.1 Table 1 gives strength ratios, corresponding to various slopes of grain for stress in bending and compression parallel to grain.
4.2.2 Strength ratios for various combinations of size and location of knot and width of face are given in Table 2, Table 3, and
Table 4. Since interpolation is often required in the development of grading rules, the use of formulas in Table 2, Table 3 and Table
4 is acceptable. These formulas are found in the Appendix.
1 1
4.2.2.1 Use of the tables is illustrated by the following example: The sizes of knots permitted in a 7 ⁄2 by 15 ⁄2-in. (190 by 394-mm)
394 mm) (actual) beam in a grade having a strength ratio of 70 % in bending are desired. The smallest ratio in the column for a
1 1
7 ⁄2-in. (190-mm) (190 mm) face in Table 2 that equals or exceeds 70 % is opposite 2 ⁄8 in. (54 mm) in the size-of-knot column.
1 1
A similar ratio in the column for 15 ⁄2-in. (394-mm) (394 mm) face in Table 3 is opposite 4 ⁄4 in. (108 mm). Hence, the permissible
1 1 1
sizes are 2 ⁄8 in. (54 mm) on the 7 ⁄2-in. (190-mm) (190 mm) face and at the edge of the wide face (see 5.3.5.2) and 4 ⁄4 in. (108
mm) on the centerline of the 15 ⁄2-in. (394-mm) (394 mm) face.
4.2.3 For all lumber thicknesses, a strength ratio of 50 % shall be used for all sizes of shakes, checks and splits. A50 % A 50 %
strength ratio is the maximum effect a shake, check or split can have on the load-carrying capacity of a bending member.
Limitations in grading rules placed on the characteristics at time of manufacture are for appearance and general utility purposes,
and these characteristics shall not be used as a basis for increasing lumber shear design values.
NOTE 2—The factor of 0.5 (50 %) is not strictly a “strength ratio” for horizontal shear, since the factor represents more than just the effects of shakes,
checks and splits. The factor also includes differences between test values obtained in Test Methods D143 shear block tests and full-size solid-sawn beam
shear tests. The strength ratio terminology is retained for compatibility with prior versions of Practicethis D143,practice, but prior provisions permitting
design increases for members with lesser-size cracks have been deleted since the factor is related to more than shakes, checks and splits.
4.2.4 Modulus of elasticity is modified by a quality factor that is related to bending strength ratio, as given in Table 5.
4.2.5 Strength ratios in tension parallel to grain are 55 % of the corresponding bending strength ratios.
4.2.6 Table 6 gives strength ratios and quality factors for the special specific gravity classes described in 4.1.9.
5. Estimation and Limitation of Growth Characteristics
5.1 General Quality of Lumber:
5.1.1 All lumber should be well manufactured.
5.1.2 Only sound wood, free from any form of decay, shall be permitted, unless otherwise specified. Unsound knots and limited
amounts of decay in its early stages are permitted in some of the lower stress-rated grades of lumber intended for light frame
construction.
5.1.3 In stress-grading, all four faces and the ends shall be considered.
5.2 Slope of Grain:
TABLE 1 Strength Ratios Corresponding to Various Slopes of
Grain
Maximum Strength Ratio, %
Bending or Compression
Slope of Grain
Tension Parallel Parallel
to Grain to Grain
1 in 6 40 56
1 in 8 53 66
1 in 10 61 74
1 in 12 69 82
1 in 14 74 87
1 in 15 76 100
1 in 16 80 .
1 in 18 85 .
1 in 20 100 .
D245 − 22
TABLE 2 Strength Ratios Corresponding to Knots in the Narrow Face of Bending Members
A
Knot Percentage Strength Ratio When Actual Width of Narrow Face, in. (mm), is
Size, in.
1 1 1 1 1 1 1 1 1 1
1 1 ⁄2 2 2 ⁄2 3 3 ⁄2 4 4 ⁄2 5 5 ⁄2 6 7 7 ⁄2 8 9 9 ⁄2 10 11 11 ⁄2 12 13 13 ⁄2 14 15 15 ⁄2 16
A
(mm)
(25) (38) (51) (64) (76) (89) (102) (114) (127) (140) (152) (178) (190) (203) (229) (241) (254) (279) (292) (305) (330) (343) (356) (381) (394) (406)
⁄4 (6) 85 89 91 93 94 95 95 96 96 96 97 97 97 97 97 97 97 97 98 98 98 98 98 98 98 98
⁄2 (13) 67 76 81 84 86 88 90 91 91 92 93 93 93 94 94 94 94 94 95 95 95 95 95 95 95 95
⁄4 (19) 48 62 70 75 79 82 84 85 87 88 89 89 90 90 91 91 91 91 92 92 92 92 92 93 93 93
1 (25) 4 49 60 68 72 75 78 80 82 84 85 86 86 87 87 88 88 88 89 89 89 90 90 90 90 90
1 ⁄4 (32) . . 49 58 64 69 72 75 78 79 81 82 83 83 84 84 85 85 86 86 87 87 87 87 88 88
1 ⁄2 (38) . . 27 49 57 62 67 70 73 75 77 78 79 80 81 81 82 82 83 83 84 84 84 85 85 85
1 ⁄4 (44) . . 15 32 49 56 61 65 68 71 73 75 75 76 77 78 78 79 80 80 81 81 82 82 83 83
2 (51) . . . 22 35 49 55 60 64 67 69 71 72 73 74 75 75 76 77 77 78 79 79 80 80 80
2 ⁄4 (57) . . . . 26 37 50 55 59 62 65 67 68 69 71 71 72 73 74 75 75 76 76 77 77 78
2 ⁄2 (64) . . . . 18 30 39 50 54 58 61 63 64 66 67 68 69 70 71 72 73 73 74 75 75 75
2 ⁄4 (70) . . . . . 23 32 40 50 54 57 60 61 62 64 65 66 67 68 69 70 70 71 72 72 73
3 (76) . . . . . . 26 34 41 50 53 56 57 59 61 62 63 64 65 66 67 68 68 69 70 70
3 ⁄4 (83) . . . . . . . . 36 45 49 52 54 55 57 59 60 61 62 63 64 65 66 67 67 68
3 ⁄2 (89) . . . . . . . . . 37 46 48 50 52 54 55 56 58 59 60 62 62 63 64 65 65
3 ⁄4 (95) . . . . . . . . . . . 45 46 48 51 52 53 55 56 57 59 60 60 61 62 63
4 (102) . . . . . . . . . . . . . 45 48 49 50 52 53 54 56 57 58 59 60 60
4 ⁄4 (108) . . . . . . . . . . . . . . . 46 47 49 50 51 53 54 55 56 57 58
4 ⁄2 (114) . . . . . . . . . . . . . . . . . 46 47 49 50 51 52 54 55 55
4 ⁄4 (121) . . . . . . . . . . . . . . . . . . . 46 48 49 50 51 52 53
5 (127) . . . . . . . . . . . . . . . . . . . . 45 46 47 49 49 50
A
Ratios Ratios corresponding to other sizes of knots and face widths can be found by linear interpolation.

D245 − 22
TABLE 3 Strength Ratios Corresponding to Centerline Knots in the Wide Face of Bending Members, and to Knots in Compression Members
A
Size of Percentage Strength Ratio When Actual Width of Wide Face, in. (mm), is
Knot, in.
1 1 1 1 1 1 1 1
3 3 ⁄2 4 4 ⁄2 5 5 ⁄2 6 7 7 ⁄2 8 9 9 ⁄2 10 11 11 ⁄2 12 13 13 ⁄2 14 15 15 ⁄2 16 18 20 22 24
A
(mm)
(76) (89) (102) (114) (127) (140) (152) (178) (190) (203) (229) (241) (254) (279) (292) (302) (330) (343) (356) (381) (394) (406) (457) (508) (559) (610)
⁄4 (6) 94 95 95 96 96 96 97 97 97 97 98 98 98 98 98 98 98 98 98 98 98 99 99 99 99 99
⁄2 (13) 86 88 90 91 91 92 93 94 94 95 95 95 96 96 96 96 96 96 97 97 97 97 97 97 97 97
⁄4 (19) 79 82 84 85 87 88 89 91 91 92 92 93 93 94 94 94 94 95 95 95 95 95 95 95 96 96
1 (25) 72 75 78 80 82 84 85 87 88 89 90 90 91 92 92 92 92 93 93 93 93 93 94 94 94 94
1 ⁄4 (32) 64 69 72 75 78 79 81 84 85 86 87 88 89 90 90 90 90 91 91 91 91 91 92 92 93 93
1 ⁄2 (38) 57 62 67 70 73 75 78 81 82 83 85 85 86 87 88 88 89 89 89 89 90 90 90 91 91 91
1 ⁄4 (44) 49 56 61 65 68 71 74 77 79 80 82 83 84 85 86 86 87 87 87 87 88 88 89 89 90 90
2 (51) 35 49 55 60 64 67 70 74 76 77 79 80 81 83 84 84 85 85 85 86 86 86 87 88 88 89
2 ⁄4 (57) 26 37 50 55 59 62 66 71 72 73 77 78 79 81 82 82 83 83 83 84 84 84 85 86 87 87
2 ⁄2 (64) 18 30 39 50 54 58 62 67 69 71 74 75 77 79 80 80 81 81 81 82 82 83 84 84 85 86
2 ⁄4 (70) . 23 32 40 50 54 58 64 66 68 71 73 74 76 77 78 79 79 79 80 80 81 82 83 84 84
3 (76) . . 26 34 41 50 54 61 63 65 69 70 72 74 75 76 77 77 78 78 79 79 80 81 82 83
3 ⁄4 (83) . . . 29 36 45 51 57 60 62 66 68 69 72 73 74 75 75 76 76 77 77 78 80 80 81
3 ⁄2 (89) . . . 23 31 37 47 54 57 59 64 65 67 70 71 72 73 73 74 75 75 75 77 78 79 80
3 ⁄4 (95) . . . . 26 32 38 51 54 56 61 63 65 68 69 70 71 71 72 73 73 74 75 76 77 78
4 (102) . . . . 21 28 34 47 50 53 58 60 62 66 67 68 69 69 70 71 71 72 73 75 76 77
4 ⁄4 (108) . . . . . 23 30 40 46 50 56 58 60 63 65 66 67 68 68 69 70 70 72 73 74 75
4 ⁄2 (114) . . . . . 19 26 36 41 48 53 55 58 61 63 64 65 66 66 67 68 68 70 72 73 74
4 ⁄4 (121) . . . . . . 21 33 37 41 50 53 55 59 61 62 63 64 64 65 66 67 68 70 71 73
5 (127) . . . . . . 17 29 34 38 48 50 53 57 59 60 61 62 62 64 64 65 67 68 70 71
5 ⁄4 (133) . . . . . . . 25 30 35 45 48 50 55 57 58 59 60 61 62 62 63 65 67 68 70
5 ⁄2 (140) . . . . . . . 22 27 32 39 45 48 52 54 56 57 58 59 60 61 61 63 65 67 68
5 ⁄4 (146) . . . . . . . . 24 29 37 40 46 50 52 54 55 56 57 58 59 59 62 64 65 67
6 (152) . . . . . . . . . . . 26 34 37 40 48 50 52 53 54 55 56 57 58 60 62 64 65
6 ⁄2 (165) . . . . . . . . . 19 28 32 35 41 46 48 49 50 51 53 53 54 57 59 61 62
7 (178) . . . . . . . . . 13 23 27 30 37 40 42 45 46 47 49 50 51 53 56 58 59
7 ⁄2 (190) . . . . . . . . . . 17 22 25 32 35 38 40 41 42 45 46 47 50 52 55 57
8 (203) . . . . . . . . . . . . 20 28 31 34 36 37 39 41 42 43 47 49 52 54
8 ⁄2 (216) . . . . . . . . . . . . 15 23 26 30 32 33 35 37 38 39 41 46 49 51
A
Ratios Ratios corresponding to other sizes of knots and face widths can be found by linear interpolation.

D245 − 22
TABLE 4 Strength Ratios Corresponding to Edge Knots in the Wide Face of Bending Members
A
Knot Percentage Strength Ratio When Actual Width of Wide Face, in. (mm), is
Size, in.
1 1 1 1 1 1 1 1 1
2 2 ⁄2 3 3 ⁄2 4 4 ⁄2 5 5 ⁄2 6 7 7 ⁄2 8 9 9 ⁄2 10 11 11 ⁄2 12 13 13 ⁄2 14 15 15 ⁄2 16 18 20 22 24
A
(mm)
(51) (64) (76) (89) (102) (114) (127) (140) (152) (178) (190) (203) (229) (241) (254) (279) (292) (305) (330) (343) (356) (381) (394) (406) (457) (508) (559) (610)
⁄4 (6) 83 86 88 89 91 91 92 93 94 94 94 95 95 96 96 96 97 97 97 97 97 97 97 97 97 97 97 98
⁄2 (13) 65 71 75 78 80 82 84 85 86 88 89 90 90 91 91 92 92 93 93 93 93 93 93 94 94 94 94 95
⁄4 (19) 49 57 62 67 70 73 75 77 79 82 83 84 86 86 87 88 89 89 89 89 90 90 90 90 91 91 92 92
1 (25) 27 38 51 57 61 65 68 70 73 76 77 79 81 82 83 84 85 85 85 86 86 86 87 87 88 88 89 89
1 ⁄4 (32) 16 27 36 47 52 57 60 63 66 71 72 74 76 77 78 80 81 82 82 82 83 83 83 84 84 85 86 86
1 ⁄2 (38) . 17 26 34 40 49 53 57 60 64 67 69 72 73 74 76 77 78 78 79 79 80 80 80 81 82 83 84
1 ⁄4 (44) . . 19 26 33 38 47 50 54 60 62 64 67 69 70 72 74 75 75 75 76 77 77 77 78 79 80 81
2 (51) . . . 19 26 32 37 45 49 55 57 59 63 65 66 69 70 71 72 72 73 73 74 74 75 77 78 78
2 ⁄4 (57) . . . . 20 26 31 36 40 50 52 55 59 61 62 65 66 68 68 69 69 70 71 71 73 74 75 76
2 ⁄2 (64) . . . . 15 21 26 31 35 45 48 51 55 57 59 62 63 65 65 66 66 67 68 68 70 71 72 73
2 ⁄4 (70) . . . . . 16 21 26 30 38 41 46 51 53 55 59 60 61 62 63 63 64 65 65 67 68 70 71
3 (76) . . . . . . 17 21 26 33 37 40 47 50 52 55 57 58 59 60 60 61 62 62 64 66 67 68
3 ⁄4 (83) . . . . . . . 17 22 29 32 36 41 46 48 52 54 55 56 57 57 58 59 60 62 63 65 66
3 ⁄2 (89) . . . . . . . . 18 26 29 32 39 41 43 49 52 52 53 54 54 56 56 56 59 61 62 63
3 ⁄4 (95) . . . . . . . . . 23 26 29 35 37 40 46 48 49 50 51 52 53 54 54 56 58 60 61
4 (102) . . . . . . . . . . 22 26 32 34 37 41 45 47 48 48 49 50 51 52 54 56 58 59
4 ⁄4 (108) . . . . . . . . . . . 22 28 31 34 38 40 42 44 45 46 48 48 49 51 54 55 57
4 ⁄2 (114) . . . . . . . . . . . 20 26 28 31 35 37 39 41 42 43 45 46 47 49 51 53 54
4 ⁄4 (121) . . . . . . . . . . . . 23 26 28 33 35 37 39 40 41 42 43 44 47 49 51 52
5 (127) . . . . . . . . . . . . . . . . 25 30 32 34 36 37 38 40 40 41 44 47 49 50
A
Ratios Ratios corresponding to other sizes of knots and face widths can be found by linear interpolation.

D245 − 22
TABLE 5 Quality Factors for Modulus of Elasticity
Quality Factor for
Bending Strength
Modulus of
Ratio, %
Elasticity, %
$55 100
45 to 54 90
#44 80
TABLE 6 Strength Ratios and Quality Factors for Special Specific
Gravity Classifications
Specific Gravity Classification, %
Property
Close Medium
Dense
Grain Grain
Bending stress
Tensile stress parallel to grain
Compressive stress parallel to grain 117 107 100
Compressive stress perpendicular to
grain
Modulus of elasticity 105 100 100
5.2.1 Slope of grain resulting from either diagonal sawing or from spiral or twisted grain in the tree is measured by the angle
between the direction of the fibers and the edge of the piece. The angle is expressed as a slope. For instance, a slope of grain of
1 in 15 means that the grain deviates 1 in. (2.5(25 mm) from the edge in 15 in. (381 mm) of length.
5.2.2 When both diagonal and spiral grain are present, the combined slope of grain is taken as the effective slope.
5.2.3 Slope of grain is measured and limited at the zone in the length of a structural timber that shows the greatest slope. It shall
be measured over a distance sufficiently great to define the general slope, disregarding such short local deviations as those around
knots except as indicated in 5.2.5.
5.2.4 In 1-in. nominal boards (See Terminology D9), or similar small sizes of lumber, a general slope of grain anywhere in the
length shall not pass completely through the thickness of the piece in a longitudinal distance in inches less than the number
expressing the specified permissible slope. Where such a slope varies across the width of the board, its average may be taken.
5.2.5 Local deviations must be considered in small sizes, and if a local deviation occurs in a piece less than 4 in. nominal in width
or on the narrow face of a piece less than 2 in. nominal in thickness, and is not associated with a permissible knot in the piece,
the measurement of slope shall include the local deviation.
5.3 Knots:
5.3.1 A knot cluster is treated as an individual knot. Two or more knots closely spaced, with the fibers deflected around each knot
individually, are not a cluster.
5.3.2 Holes associated with knots are measured and limited in the same way as knots.
5.3.3 A knot on the wide face of a bending or tension member is considered to be at the edge of the wide face if the center of
the knot lies within two thirds of the knot diameter from the edge.
5.3.4 Knots in Dimension Lumber:
5.3.4.1 Knots in dimension lumber may be measured by displacement method, in which the proportion of the cross section of the
knot to the cross section of the piece is multiplied by actual face width to establish the equivalent knot size (see Fig. 1). This value
is used in the strength ratio tables.
5.3.4.2 Alternatively, knots in dimension lumber may be measured on the surface of the piece. Methods of measuring knots by
this alternative are given in 5.3.4.3 – 5.3.4.5.
D245 − 22
FIG. 1 Measurement of Knots in Dimension Lumber Using Displacement Method (Primary Method)
5.3.4.3 The size of a knot on a narrow face is its width between lines enclosing the knot and parallel to the edges of the piece (Fig.
2). A narrow-face knot that appears also in the wide face of a side-cut piece (but does not contain the intersection of those faces)
is measured and graded on the wide face.
5.3.4.4 The size of a knot on a wide face is the average of its largest and smallest dimensions (Fig. 2).
5.3.4.5 Any knot that contains the intersection of two faces, including a knot extending entirely across the width of a face in a
side-cut piece, is a corner knot. A corner knot is measured on its end between lines parallel to the edges of the piece and is graded
with respect to the face on which it is measured (Fig. 2). A corner knot in a piece containing the pith is measured either by its width
on the narrow face between lines parallel to the edge, or by its smallest diameter on the wide face, whichever is more restrictive
(Fig. 2). If a corner knot appears also on an opposite face, its limitation there as well as on the corner is necessary.
5.3.4.6 The sum of the sizes of all knots in any 6 in. (152 mm) of length of piece shall not exceed twice the size of the largest
permitted knot. Two or more knots of maximum or near maximum permissible size shall not be allowed in the same 6 in. (152
mm) of length on a face. Any combination of knots that, in the judgment of the lumber grader, will make the piece unfit for its
intended use, shall not be admitted.
FIG. 2 Measurement of Knots in Dimension Lumber Using Alternative Method
D245 − 22
5.3.4.7 For sizes 3 by 3 in. nominal and smaller the effects of grain distortion associated with knots can be so severe that all knots
shall be limited as if they were wide-face edge knots in the face on which they appear.
5.3.4.8 Where the grade is intended to be used for single-span bending applications only, the sizes of knots on narrow faces and
at the edge of wide faces may increase proportionately from the size permitted in the middle one third of the length to twice that
size at the ends of the piece, except that the size of no knot shall exceed the size permitted at the center of the wide face. The size
of knots on wide faces may be increased proportionately from the size permitted at the edge to the size permitted at the centerline
(Fig. 3).
5.3.4.9 Where the grade is intended to be used on continuous spans, the restrictions for knots in the middle one third of their
lengths shall be applied to the middle two thirds of the length of pieces continuous on three supports, and to the full length of pieces
continuous on four or more supports.
5.3.5 Knots in Beams and Stringers:
5.3.5.1 The size of a knot on a narrow face of a beam or stringer is its width between lines enclosing the knot and parallel to the
edges of the piece (Fig. 4). When a knot on a narrow face of a side-cut piece extends into the adjacent one fourth of the width
of a wide face, it is measured on the wide face.
5.3.5.2 The size of a knot on the wide face is measured by its smallest diameter (Fig. 4). An edge knot on the wide face is limited
to the same size as a knot on the narrow face.
5.3.5.3 A corner knot in a beam or stringer containing the pith is measured either by its width on the narrow face between lines
parallel to the edges or by its smallest diameter on the wide face, whichever is greater (Fig. 4). A corner knot in a side-cut piece
is measured by whichever of these two is least.
5.3.5.4 The sum of the sizes of all knots within the middle one half of the length of a face, in a beam 20 ft (61(6.1 m) or less in
length, when measured as specified for the face under consideration, shall not exceed four times the size of the largest knot allowed
on that face. This restriction in a beam longer than 20 ft (61(6.1 m) shall apply to any 10 ft (30(3.0 m) of length within the middle
one half of the length.
5.3.5.5 Where the grade is used for single-span bending applications only, the sizes of knots on narrow faces and at the edges of
wide faces may be increased proportionately from the size permitted in the middle one third of the length to twice that size at the
ends of the piece, except that the size of no knot shall exceed the size permitted at the center of the wide face. The size of knots
on wide faces may be increased proportionately from the size permitted at the edge to the size permitted at the center line (Fig.
3).
A, maximum size on narrow face in middle third of length with a uniform increase to 2A but not to exceed B, at the ends.
B, maximum size at center of wide face.
C, maximum size at edge of wide face in middle third of length with a uniform increase to 2C but not to exceed B at the ends and a uniform increase to B at the center
of the wide face. In beams and stringers, A and C are equal.
L, length.
W, width of wide face.
T, width of narrow face.
FIG. 3 Maximum Size of Knots Permitted in Various Parts of Joists and Planks, and Beams and Stringers
D245 − 22
FIG. 4 Measurement of Knots in Beams and Stringers
5.3.5.6 Where the grade is intended to be used on continuous spans, the restrictions for knots in the middle one third of their
lengths shall be applied to the middle two thirds of the length of pieces continuous on three supports, and to the full length of pieces
continuous on four or more supports.
5.3.6 Knots in Posts and Timbers:
5.3.6.1 The size of a knot on any face of a post or timber is taken as the diameter of a round knot, the lesser of the two diameters
of an oval knot, or the greatest diameter perpendicular to the length of a spike knot (Fig. 5).
5.3.6.2 A corner knot is measured wherever the measurement will represent the true diameter of the branch causing the knot.
5.3.6.3 The sum of the sizes of all knots in any 6 in. (152 mm) of length of a post or timber shall not exceed twice the size of
the largest permitted knot. Two or more knots of maximum or near maximum permissible size shall not be allowed in the same
6 in. (152 mm) of length on a face.
5.3.6.4 In compression members with greater width than thickness, the sizes of knots in both the narrow and the wide faces are
allowed up to the size permitted in the wide face.
5.3.7 Knots in Stress-Rated Boards:
FIG. 5 Measurement of Knots in Posts and Timbers or Other Compression Members
D245 − 22
5.3.7.1 Knots in stress-rated nominal boards are measured by the average of the widths on the two opposite faces, each width being
taken between lines parallel to the edges of the board. Knots are not measured on the narrow face, since they appear also in one
or both wide faces.
5.3.7.2 The sum of the sizes of all knots in any 6 in. (152 mm) of length shall not exceed twice the size of the largest permitted
knot. Two or more knots of maximum permissible size shall not be allowed in the same 6 in. (152 mm) of length on a face.
5.4 Shakes, Checks, and Splits:
5.4.1 Shakes are measured at the ends of the piece. The size of a shake is the distance between lines enclosing the shake and
parallel to the wide face of the piece.
5.4.2 Splits and checks are treated as “equivalent shakes,” but are measured differently. The size of a side check is its average
depth of penetration into the piece, measured from and perpendicular to the surface of the wide face on which it appears. The size
of an end split or end check is one third of its average length measured along the length of a piece, except as noted in 5.4.6.
5.4.3 In single-span bending members, shakes, checks, and splits are restricted only for a distance from each end equal to three
times the width of the wide face, and within the critical zone, only in the middle one half of the wide face. For multiple-span
bending members, shakes, checks, and splits are restricted throughout the length in the middle one half of the wide face.
5.4.4 Outside the critical zone in bending members, and in axially loaded members, shakes, checks, and splits have little or no
effect on strength properties and are not restricted for that reason. It may be advisable to limit them in some applications for
appearance purposes, or to prevent moisture entry and subsequent decay.
5.4.5 The grading of any combination of shakes, checks, and splits is based on the grader’s judgment of the probable effects of
seasoning or loading in service on the combination. Where a combination of two checks in opposite faces, a check and a split, a
check and a shake, or a split and a shake may later become a single horizontal shear plane, the sum of the sizes in the combination
is restricted to the allowable size of shakes. Where such a combination is not additive in this way, only the largest single
characteristic is considered.
5.4.6 Where 2-in. nominal dimension (See Terminology D9) is to be used in light building construction in which the shear stress
is not critical, a more liberal provision on end splits may be made. The size of the split, measured differently than in 5.4.2, is its
average length along the length of the piece.
5.4.7 Provisions for shakes, checks, and splits as described in 5.4.1 – 5.4.6 are applicable to boards if used where shear strength
is important.
5.5 Wane is permissible in all grades of bending members as far as strength properties are concerned, but “free from wane” may
be specified when required by appearance, connections, bearing, or other factors of use.
5.6 Specific Gravity Selection :
5.6.1 Lumber may be selected as dense by grain characteristics for Douglas-fir and southern pine. To be classified dense the wood
shall average on one end or the other of each piece not less than six annual rings per inch (25 mm) and one third or more
summerwood (the darker, harder portion of the annual ring) measured on a representative radial line. Pieces that average not less
than four annual rings per inch (25 mm) shall be accepted as dense if they average one half or more summerwood. The contrast
in color between springwood and summerwood in either case shall be distinct.
5.6.1.1 To ensure a representative radial line, measurement shall be made over a continuous length of 3 in. (76 mm) or as nearly
3 in. (76 mm) as is available. The length shall be centrally located in side-cut pieces. In pieces containing the pith, the measurement
may exclude an inner portion of the radius amounting to approximately one quarter of the least dimension of the piece.
5.6.2 Dense material of any species may be selected by methods other than described above, provided that such methods ensure
the increases in properties given in 4.2.6.
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5.6.2.1 One test that may be used to determine whether the requirements of 5.6.2 are met relative to strength properties is to show
that:
2 2
1.17 EV % A1BG 2 1.645 =B s 1rms (1)
~ ! ~ !
where:
EV = 5 % exclusion value of a strength property for the species, as described in Test Methods D2555.
A and B = regression coefficients of strength property versus specific gravity for the species given in Table 7,
G = average specific gravity (based on green volume and ovendry weight) of the pieces selected as dense by mechanical
means,
s = the standard deviation of specific gravity of the pieces selected as dense by mechanical means, and
rms = residual mean square (the square of the standard deviation about regression given in Table 7) associated with the
regression for strength property versus specific gravity for the species.
5.6.2.2 One test that may be used to determine whether the requirements of 5.6.2 are met relative to modulus of elasticity is to
show that:
¯
1.05 Y % A1BG (2)
where:
Y¯ = average modulus of elasticity of the species, as given in Test Methods D2555,
A andB = regression coefficients of modulus of elasticity versus specific gravity for the species given in Table 9, and
G = average specific gravity (based on green volume and ovendry weight) of the pieces selected as dense by mechanical
means.
5.6.3 Lumber may be selected as close grain for Douglas-fir from the Coast Region, redwood, and southern pine. To be classified
as close grain the wood shall average on one end or the other of each piece not less than 6 nor more than 30 annual rings per inch
(25 mm) measured on a representative radial line. To ensure a representative radial line, measurement shall be made as in 5.6.1.1.
Pieces averaging at least 5 or more than 30 rings per inch shall be accepted as close-grained if the measurement shows one third
or more summerwood. Visually selected close-grained redwood shall average in one piece not less than 8 nor more than 40 annual
rings per inch.
5.6.4 Close-grained wood of any species may be selected by methods other than described above, provided that such methods
ensure the increases in properties given in 4.2.6.
5.6.4.1 One test that may be used to determine whether the requirements of 5.6.4 are met is to show that:
2 2
1.07 EV % A1BG 2 1.645 =B s 1rms (3)
~ ! ~ !
where the symbols have the meaning given in 5.6.2.1.
5.6.5 It is advisable to reject exceptionally lightweight pieces from the highest grades. For the softwoods with pronounced
summerwood, selection for medium grain serves this purpose. Medium-grained wood shall average on one end or the other of each
piece not less than four annual rings per inch (25 mm), measured on a representative radial line. To ensure a representative radial
line, measurement shall be made as in 5.6.1.1.
6. Allowable Properties for Timber Design
6.1 Principles of Determination of Allowable Properties—Test Methods D2555 provide information on clear wood property values
and their variation. From these values, allowable properties are obtained for green lumber, according to the permitted growth
characteristics as discussed in Sections 4 and 5. The allowable properties are based on normal loading duration, and the assumption
that design loads are realistic and that each member carries its own load. Allowable properties can be determined for individual
species or groups of species. The allowable modulus of elasticity and compression perpendicular-to-grain stress are intended to be
average values for the species group and stress grade; the other allowable stresses are intended to be less than the stress permissible
for 95 % of the pieces in a species group and stress grade. In other words, most allowable stresses are based on the concept of a
5 % exclusion limit.
D245 − 22
TABLE 7 Regression Coefficients for Strength Properties Versus Specific Gravity
NOTE 1—These coefficients are extracted from Refs (6) and (7).
Properties
Compression Parallel to Grain, max Compression Perpendicular to
Modulus of Rupture Modulus of Elasticity Shear
crushing Grain
Species or Re-
Standard Standard Standard Standard Standard
gion or Both
Deviation Deviation Deviation Deviation Deviation
A A A A A A A A A A
A B A B A B A B A B
from from from from from
B B B B B
Regression Regression Regression Regression Regression
Douglas-fir
Coast −1757 20 894 572 −259 4036 216 −1087 10 803 403 193 1580 96 . . .
Interior west −1750 20 694 571 −408 4203 215 −1548 11 854 414 174 1669 98 . . .
Interior north −1396 19 783 635 −212 3631 208 −905 9797 360 184 1711 94 . . .
Interior south 25 15 679 576 151 2346 171 21 7174 369 18 2171 118 . . .
White fir −277 16 650 588 −226 3770 183 −854 10 200 265 306 1223 56 . . .
Cal. red fir 57 15 993 562 179 2759 240 −267 8411 286 287 1336 134 . . .
Grand fir 2516 9591 538 697 1650 148 991 5623 269 218 1505 72 . . .
Pacific silver fir −1861 21 086 447 109 3343 169 −568 9459 227 70 1725 56 . . .
Noble fir −1148 19 518 487 −588 5253 214 −1285 11 467 272 275 1408 122 . . .
Western hemlock −365 16 623 637 214 2597 218 −764 9804 329 221 1529 67 . . .
Western larch 1004 13 905 742 726 1534 237 −31 7921 414 294 1204 61 . . .
Black cottonwood 352 14 269 815 263 2580 176 484 5396 308 52 1761 69 . . .
Southern Pine
Loblolly −1318 18 287 717 −317 3648 258 −967 9501 354 224 1359 86 −150 1191 98
Longleaf −986 17 609 811 −281 3453 216 −466 8851 485 298 1365 91 −135 1124 133
Shortleaf 67 15 682 851 227 2472 237 −300 8141 383 −34 1999 73 24 644 101
Slash 47 16 152 551 198 2492 252 778 5690 423 391 1070 110 57 874 143
A
Coefficients Coefficients in the relation Y = A + BX where Y = mechanical property (in 1000 psi for MOE; in psi for all others) and X = specific gravity.
B
The The standard deviation from regression is a measure of dispersion about the regression, representing the standard deviation of property about the line at any choice of specific gravity. This parameter is often called
the standard error of estimate. Units are in psi except MOE, which is in 1000 psi.

D245 − 22
6.1.1 Allowable property values shall be rounded to the nearest value having increments as shown below, after all adjustments in
the allowable properties have been made.
nearest 50 psi (340 kPa) for allowable
Bending
stress of 1000 psi (6.9 MPa) or
Tension parallel to grain
greater
Compression parallel to grain 5
nearest 25 psi (170 kPa) otherwise
Horizontal shear
Compression perpendicular nearest 5 psi (34 kPa)
to grain
Modulus of elasticity nearest 100 000 psi (69 GPa)
The The rounding rules of IEEE/ASTM SI-10, 4.2, shall be followed.
6.2 The 5 % exclusion limit for bending strength, tensile strength parallel to grain, compressive strength parallel to grain, and
horizontal shear strength for clear straight-grained wood in the green condition shall be obtained for any species or group of species
from Test Methods D2555. These properties when
...