ASTM D6841-16
Standard Practice for Calculating Design Value Treatment Adjustment Factors for Fire-Retardant-Treated Lumber

Standard No.

ASTM D6841-16

Release Date

2016

Published By

American Society for Testing and Materials (ASTM)

Status

Be replaced

Replace By

ASTM D6841-21

Latest

ASTM D6841-21

Scope

5.1 Fire-retardant-treatments are used to reduce the flame-spread characteristics of wood. Chemicals and redrying conditions employed in treatments are known to modify the strength properties of the wood product being treated. This practice gives procedures for fire-retardant chemical manufacturers to use to calculate the effects of their treatment on lumber used in normal and elevated temperature service conditions.

5.2 The effect of fire-retardant treatments on the strength of lumber used in roof framing applications is time related. In this practice, the cumulative effect on strength of annual thermal loads from all temperature bins is increased 50 times to establish treatment adjustment factors for fire-retardant treated lumber roof framing.

5.3 The procedures of Test Method D5664 employ an elevated temperature intended to produce strength losses in a short period of time. Although the exposure is much more severe than that which occurs in an actual roof system, the chemical reactions that occur in the laboratory test are considered to be the same as those occurring over long periods of time in the field.

5.4 Treatment adjustment factors developed under this practice apply to lumber installed in accordance with construction practices recommended by the fire-retardant chemical manufacturer which include avoidance of direct wetting, precipitation or frequent condensation. Application of this practice is limited to roof applications with design consistent with 1.3.

1.1 This practice covers procedures for calculating treatment adjustment factors to be applied to design values for fire-retardant-treated lumber used at ambient temperatures [service temperatures up to 100°F (38°C)] and as framing in roof systems.

1.2 These design value treatment adjustment factors for the properties of extreme fiber in bending, tension parallel to grain, compression parallel to grain, horizontal shear, and modulus of elasticity are based on the results of strength tests of matched treated and untreated small clear wood specimens after conditioning at nominal room temperatures [72°F (22°C)] and of other similar specimens after exposure at 150°F (66°C). The test data are developed in accordance with Test Method D5664. Guidelines are provided for establishing adjustment factors for the property of compression perpendicular to grain and for connection design values.

1.3 Treatment adjustment factors for roof framing applications are based on computer generated thermal load profiles for normal wood roof construction used in a variety of climates as defined by weather tapes of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE).2 The solar loads, moisture conditions, ventilation rates, and other parameters used in the computer model were selected to represent typical sloped roof designs. The thermal loads in this practice are applicable to roof slopes of 3 in 12 or steeper, to roofs designed with vent areas and vent locations conforming to national standards of practice and to designs in which the b......

ASTM D6841-16 Referenced Document

• ASTM D5664 Standard Test Method for Evaluating the Effects of Fire-Retardant Treatments and Elevated Temperatures on Strength Properties of Fire-Retardant Treated Lumber
• ASTM D6305 Standard Practice for Calculating Bending Strength Design Adjustment Factors for Fire-Retardant-Treated Plywood Roof Sheathing
• ASTM D9 Standard Terminology Relating to Wood

ASTM D6841-16 history

• 2021 ASTM D6841-21 Standard Practice for Calculating Design Value Treatment Adjustment Factors for Fire-Retardant-Treated Lumber
• 2016 ASTM D6841-16 Standard Practice for Calculating Design Value Treatment Adjustment Factors for Fire-Retardant-Treated Lumber
• 2015 ASTM D6841-15 Standard Practice for Calculating Design Value Treatment Adjustment Factors for Fire-Retardant-Treated Lumber
• 2008 ASTM D6841-08 Standard Practice for Calculating Design Value Treatment Adjustment Factors for Fire-Retardant-Treated Lumber
• 2003 ASTM D6841-03 Standard Practice for Calculating Design Value Treatment Adjustment Factors for Fire-Retardant-Treated Lumber
• 2002 ASTM D6841-02 Standard Practice for Calculating Design Value Treatment Adjustment Factors for Fire-Retardant-Treated Lumber