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| Performance
of Finger-Jointed Lumber in Fire-Resistance-Rated Wall Assemblies |
The last
sentence of IBC Section 2303.1.1 Sawn Lumber, states, “Approved
end-jointed lumber is permitted to be used interchangeably
with solid-sawn members of the same species and grade.” Although
no problems have been brought to our attention with the fire-performance
of end-jointed lumber in the field, in response to concerns
raised by the wood products industry the American Lumber Standards
Committee (ALSC) recently modified the ALSC Glued
Lumber Policy to add elevated-temperature performance requirements
for end-jointed lumber adhesives intended for use in fire resistance-rated
assemblies. End-jointed lumber manufactured with adhesives
which meet the new requirements is being designated as "Heat
Resistant Adhesive" or "HRA" on the grade stamp.
Under
the ALSC Glued Lumber Policy, Heat Resistant Adhesives
are being evaluated according to the American Forest & Paper
Association's Elevated-Temperature
Adhesive Qualification Procedure. This testing protocol
requires an adhesive to be exposed to elevated temperatures
during a standard ASTM E119 fire test of a loadbearing
end-jointed wall stud assembly loaded to 100% of the stud's
allowable design load. The adhesive tested qualifies if
the wall assembly achieves a one hour fire resistance rating
in the E119. The
new HRA mark is applicable to all end-jointed lumber manufactured
under the quality-auditing program of an ALSC-accredited grading
agency. End-jointed lumber manufactured with an adhesive not
tested or not qualified as a Heat Resistant Adhesive will be
designated as "Non-Heat Resistant Adhesive" or "non-HRA" on
the grade stamp, and will continue to meet building code requirements
when used in unrated construction.
Background
The American Forest & Paper
Association (AF&PA) and its member companies have a long
history of conducting research to ensure the safety of their
products. In cooperation with the USDA Forest Products Laboratory
and Forintek Canada Corporation, Canada’s forest products
laboratory, AF&PA initiated a research program to better
understand the performance of adhesives used in end-jointed
lumber in fire-resistance-rated assemblies. As part of the
research, the wood products industry conducted ASTM E119
fire-resistance tests on finger-jointed lumber wall assemblies
in March 2006, August 2006, and November 2006, at NGC Testing
Services in Buffalo, New York. This research showed that
all adhesives do not perform the same in elevated temperature
tests. Consequently, adhesives used in end-jointed lumber
now must be qualified for use in fire-resistance-rated assemblies.
The following
table summarizes the full-scale fire-resistance test results.
All fire tests were conducted on the wall assembly design
specified in 2003 International Building Code Table
720.1(2), Item Number 15-1.14 (identical to 2006 International
Building Code Table 720.1(2), Item Number 15-1.15).
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| Type
of Lumber |
Assembly
Loading |
Fire
Resistance Rating
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Finger-jointed
lumber studs made with a Phenol Resorcinol Formaldehyde
adhesive |
100%
design |
1-hour |
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Finger-jointed
lumber studs made with a Polyurethane adhesive |
100%
design |
51
min. |
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Finger-jointed
lumber studs made with a Polyvinyl Acetate adhesive |
100%
design |
49
min. |
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A number of finger-jointed
lumber manufacturers have indicated that they have conducted
proprietary tests of their own products and successfully
achieved one-hour fire-resistance ratings in their assemblies.
For more information, please contact the American Forest & Paper
Association at
1-202-463-4713 or awcinfo@afandpa.org.
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AF&PA/American Wood
Council – March 2007
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