ASTM D6305-02

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Designation: D 6305 – 02
Standard Practice for
Calculating Bending Strength Design Adjustment Factors
1
for Fire-Retardant-Treated Plywood Roof Sheathing
This standard is issued under the fixed designation D 6305; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope bility of regulatory limitations prior to use.
1.1 This practice covers procedures for calculating bending
2. Referenced Documents
strength design adjustment factors for fire-retardant-treated
2.1 ASTM Standards:
plywood roof sheathing. The methods utilize the results of
3
D 9 Terminology Relating to Wood
strength testing after exposure at elevated temperatures and
D 5516 Test Method for Evaluating the Flexural Properties
computer-generated thermal load profiles reflective of expo-
of Fire-Retardant Treated Softwood Plywood Exposed to
sures encountered in normal service conditions in a wide
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Elevated Temperatures
variety of climates.
1.2 Necessarily, common laboratory practices were used to
3. Terminology
develop the methods herein. It is assumed that the procedures
3.1 Definitions:
will be used for fire-retardant-treated plywood installed using
3.1.1 Definitions used in this practice are in accordance with
appropriate construction practices recommended by the fire
Terminology D 9.
retardant chemical manufacturers, which include avoiding
3.2 Definitions of Terms Specific to This Standard:
exposure to precipitation, direct wetting, or regular condensa-
3.2.1 bin mean temperature—10°F (5.5°C) temperature
tion.
ranges having mean temperatures of 105 (41), 115 (46), 125
1.3 The heat gains, solar loads, roof slopes, ventilation rates,
(52), 135 (57), 145 (63), 155 (68), 165 (74), and 175°F (79°C).
and other parameters used in this practice were chosen to
reflect common sloped roof designs. This practice is applicable
4. Summary of Practice
to roofs of 3 in 12 or steeper slopes, to roofs designed with vent
4.1 The test data determined by Test Method D 5516 are
areas and vent locations conforming to national standards of
used to develop adjustment factors for fire-retardant treatments
practice and to designs in which the bottom side of the
to apply to untreated-plywood design values. The test data are
sheathing is exposed to ventilation air. These conditions may
used in conjunction with climate models and other factors and
not apply to significantly different designs and therefore this
the practice thus extends laboratory strength data measured
practice may not apply to such designs.
after accelerated aging to design value recommendations.
1.4 Information and a brief discussion supporting the pro-
visions of this practice are in the Commentary in the appendix.
5. Significance and Use
A large, more detailed, separate Commentary is also available
5.1 This practice develops treatment factors that shall be
2
from ASTM.
used by fire retardant chemical manufacturers to adjust bending
1.5 The methodology in this practice is not meant to account
strength design values for untreated plywood to account for the
for all reported instances of fire-retardant plywood undergoing
fire-retardant treatment effects. This practice uses data from
premature heat degradation.
reference thermal-load cycles designed to simulate tempera-
1.6 This practice is written in inch-pound units with SI units
tures in sloped roofs of common design to evaluate products
provided in parentheses for information only.
for 50 iterations.
1.7 This standard does not purport to address all of the
5.2 This practice applies to material installed using con-
safety concerns, if any, associated with its use. It is the
struction practices recommended by the fire retardant chemical
responsibility of the user of this standard to establish appro-
manufacturers that include avoiding exposure to precipitation,
priate safety and health practices and determine the applica-
direct wetting, or regular condensation. This practice is not
meant to apply to buildings with significantly different designs
1
This practice is under the jurisdiction of ASTM Committee D07 on Wood and
than those described in 1.3.
is the direct responsibility of Subcommittee D07.07 on Fire Performance of Wood.
5.3 Test Method D 5516 caused thermally induced strength
Current edition approved April 10, 2002. Published June 2002. Originally
e1
published as D 6305-98. Last previous edition D 6305-98 .
2
Commentary on this practice is available from ASTM Headquarters. Request
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File No. D07–1004. Annual Book of ASTM Standards, Vol 04.10.
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