ASTM D245-06(2011)

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

SIGNIFICANCE AND USE
Need for Lumber Grading:  
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.  
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.
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 str...
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 Use3 Basic Principles of Strength Ratios4 Estimation and Limitation of Growth Characteristics5 Allowable Properties for Timber Design6 Modification of Allowable Properties for Design Use7 Example of Stress-Grade Development8
1.4 The values given in parentheses are provided for information purposes only.
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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 30-Sep-2011
• ICS: 79.040 - Wood, sawlogs and sawn timber
• Technical Committee: D07 - Wood
• Drafting Committee: D07.02 - Lumber and Engineered Wood Products

Relations

• Replaces: ASTM D245-06 - Standard Practice for Establishing Structural Grades and Related Allowable Properties for Visually Graded Lumber
• Effective Date: 01-Oct-2011
• Referred By: ASTM D3957-09(2020) - Standard Practices for Establishing Stress Grades for Structural Members Used in Log Buildings
• Effective Date: 01-Oct-2011
• Referred By: ASTM D2899-12(2017) - Standard Practice for Establishing Allowable Stresses for Round Timber Piles
• Effective Date: 01-Oct-2011
• Referred By: ASTM D6555-17 - Standard Guide for Evaluating System Effects in Repetitive-Member Wood Assemblies
• Effective Date: 01-Oct-2011
• Referred By: ASTM D6570-18a(2023)e1 - Standard Practice for Assigning Allowable Properties for Mechanically Graded Lumber
• Effective Date: 01-Oct-2011
• Referred By: ASTM D9-20 - Standard Terminology Relating to Wood and Wood-Based Products
• Effective Date: 01-Oct-2011
• Referred By: ASTM D5456-21e1 - Standard Specification for Evaluation of Structural Composite Lumber Products
• Effective Date: 01-Oct-2011
• Referred By: ASTM D7147-21 - Standard Specification for Testing and Establishing Allowable Loads of Joist Hangers
• Effective Date: 01-Oct-2011
• Referred By: ASTM D3737-18e1 - Standard Practice for Establishing Allowable Properties for Structural Glued Laminated Timber (Glulam)
• Effective Date: 01-Oct-2011
• Referred By: ASTM D2915-17(2022) - Standard Practice for Sampling and Data-Analysis for Structural Wood and Wood-Based Products
• Effective Date: 01-Oct-2011
• Referred By: ASTM D5574-94(2021) - Standard Test Methods for Establishing Allowable Mechanical Properties of Wood-Bonding Adhesives for Design of Structural Joints
• Effective Date: 01-Oct-2011
• Referred By: ASTM D5055-19e1 - Standard Specification for Establishing and Monitoring Structural Capacities of Prefabricated Wood I-Joists
• Effective Date: 01-Oct-2011
• Referred By: ASTM D7341-21 - Standard Practice for Establishing Characteristic Values for Flexural Properties of Structural Glued Laminated Timber by Full-Scale Testing
• Effective Date: 01-Oct-2011
• Referred By: ASTM D2555-17a - Standard Practice for Establishing Clear Wood Strength Values
• Effective Date: 01-Oct-2011
• Referred By: ASTM D6815-22a - Standard Specification for Evaluation of Duration of Load and Creep Effects of Wood and Wood-Based Products
• Effective Date: 01-Oct-2011

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D245 − 06 (Reapproved 2011)
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 2. Referenced Documents
2 3
1.1 This practice (1,2) covers the basic principles for 2.1 ASTM Standards:
establishing related unit stresses and stiffness values for design D9 Terminology Relating to Wood and Wood-Based Prod-
with visually-graded solid sawn structural lumber. This prac- ucts
tice starts with property values from clear wood specimens and D143 Test Methods for Small Clear Specimens of Timber
includes necessary procedures for the formulation of structural D2555 PracticeforEstablishingClearWoodStrengthValues
grades of any desired strength ratio. E105 Practice for Probability Sampling of Materials
IEEE/ASTM SI-10 Practice for Use of the International
1.2 The grading provisions used as illustrations herein are
System of Units (SI) (the Modernized Metric System)
not intended to establish grades for purchase, but rather to
show how stress-grading principles are applied. Detailed grad-
3. Significance and Use
ing rules for commercial stress grades which serve as purchase
3.1 Need for Lumber Grading:
specifications are established and published by agencies which
3.1.1 Individual pieces of lumber, as they come from the
formulate and maintain such rules and operate inspection
saw, represent a wide range in quality and appearance with
facilities covering the various species.
respect to freedom from knots, cross grain, shakes, and other
1.3 The material covered in this practice appears in the
characteristics. Such random pieces likewise represent a wide
following order:
range in strength, utility, serviceability, and value. One of the
Section
obvious requirements for the orderly marketing of lumber is
Scope 1
the establishment of grades that permit the procurement of any
Significance and Use 3
required quality of lumber in any desired quantity. Maximum
Basic Principles of Strength Ratios 4
Estimation and Limitation of Growth Characteristics 5
economy of material is obtained when the range of quality-
Allowable Properties for Timber Design 6
determining characteristics in a grade is limited and all pieces
Modification of Allowable Properties for Design Use 7
are utilized to their full potential. Many of the grades are
Example of Stress-Grade Development 8
established on the basis of appearance and physical character-
1.4 The values given in parentheses are provided for infor-
istics of the piece, but without regard for mechanical proper-
mation purposes only.
ties. Other grades, called structural or stress grades, are
1.5 This standard does not purport to address all of the
established on the basis of features that relate to mechanical
safety concerns, if any, associated with its use. It is the
properties. The latter designate near-minimum strength and
responsibility of the user of this standard to establish appro-
near-average stiffness properties on which to base structural
priate safety and health practices and determine the applica-
design.
bility of regulatory limitations prior to use.
3.1.2 Thedevelopmentofthispracticeisbasedonextensive
research covering tests of small clear specimens and of
full-sized structural members. Detailed studies have included
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
the strength and variability of clear wood, and the effect on
Wood Products.
Current edition approved Oct. 1, 2011. Published October 2011. Originally
approved in 1926. Last previous edition approved in 2006 as D245 – 06. DOI: For referenced ASTM standards, visit the ASTM website, www.astm.org, or
10.1520/D0245-06R11. 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 − 06 (2011)
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.
classes of stress-graded lumber, whether graded primarily for 4.1.9 A strength ratio can also be associated with specific
that property or not. Recommendations for allowable proper- gravity. Three selection classes called dense, close grain, and
ties may include all properties for all grades or use classes. medium grain are described herein, based on experimental
While such universal application may result in loss of effi- findings (5).
D245 − 06 (2011)
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. (2.5 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
NOTE 2—The factor of 0.5 (50 %) is not strictly a “strength ratio” for
than the number expressing the specified permissible slope.
horizontal shear, since the factor represents more than just the effects of
Where such a slope varies across the width of the board, its
shakes,checksandsplits.Thefactoralsoincludesdifferencesbetweentest
average may be taken.
values obtained in Methods D143 shear block tests and full-size solid-
5.2.5 Local deviations must be considered in small sizes,
sawn beam shear tests. The strength ratio terminology is retained for
compatibility with prior versions of Practice D143, but prior provisions
andifalocaldeviationoccursinapiecelessthan4in.nominal
permittingdesignincreasesformemberswithlesser-sizecrackshavebeen
inwidtho
...