American Fire Sprinkler Association
12750 Merit Dr., Suite 350 Dallas TX 75251
Ph: (214) 349-5965 Fax: (214) 276-0908
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TECHNICAL UPDATE
July 5, 2007
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"If wood joist construction is coated with fire retardant paint with
a flame spread rating of 25 or less, is it acceptable to eliminate
sprinklers within that area? Would it be classified as a Class A or
Class B coating?"
We have reviewed NFPA 13, 2002 edition that you indicated as the
applicable standard. Our informal interpretation is that using fire
retardant coatings in the combustible concealed space is not
acceptable to omit sprinklers.
Sections 8.14.2.11, 2002 edition and 8.15.1.2.11, 2007 edition
states, "Concealed spaces in which the exposed materials are
constructed entirely of fire-retardant treated wood as defined by
NFPA 703, Standard for the Fire Retardant Impregnated Wood and Fire
Retardant Coatings for Building Materials, shall not require
sprinkler protection." Since this section refers to fire-retardant
treated wood, the definition is located within NFPA 703. The
definition is "A wood product impregnated with chemical by a pressure
process or other means during manufacture, which is tested in
accordance with NFPA 255." In addition, there is no mention of
coatings applied to the wood to reduce the flame spread in section
8.14.1.2.11.
The use of coatings in concealed combustible spaces was addressed
during the 2006 ROP process in 13-192 Log #38 on page 52 with a final
action of "Reject." A proposal was submitted to the committee to
clean up the language since the paragraph does not explicitly specify
which method of treatment is required. Since fire-retardant treated
wood is not defined by NFPA 703, the existing wording has led to the
misunderstanding that both fire-retardant impregnated wood and wood
that has been treated with a fire-retardant coating are acceptable to
meet this exception. An informal opinion from an NFPA staff member
indicated that the writers' intent was to limit this exception to
fire-retardant impregnated wood (compliance with Chapter 2 of NFPA
703). This conclusion is reinforced by the Canadian Wood Council
(CWC) Wood Reference Handbook, which states that "Fire-retardant
treated wood (FRTW) is material which has been pressure impregnated
with special chemicals which improve the performance of wood products
in a fire." Fire retardant coatings are tested and listed for the
flame spread rating but not for the progressive burning test, and
uses are limited to the description in their listings. Anecdotal
reports of acceptance of fire-retardant coated lumber in attics has
revealed that the coating tends to flake and deteriorate, perhaps
because of humidity problems, and regular reapplications are required
to maintain the coating. The committee states on the task group's
decision is based on the NFPA 703 ROP draft with respect to the
definition of (3.3.2) "Fire Retardant-Treated Wood." And the proposed
changes to NFPA 13 will be based on the final edition of NFPA 703.
Thus, only fire retardant treated wood defined according to section
3.3.2 in NFPA 703 can be used in the concealed spaces to omit
sprinklers.
The Class A or B fire-retardant coatings has its application and
unfortunately, concealed combustible spaces to omit sprinklers is not
one of them. But for your information, when coatings are used, it has
to be applied according to the manufacturer's instructions. The type
of coating purchased and application would indicate whether it's a
Class A or Class B coating. The difference is that a Class A coating
reduces the flame spread to 25 or less, and Class B reduces the flame
spread to greater than 25 but not more than 75, and both have a smoke
developed rating not exceeding 200 when tested in accordance with
NFPA 225.
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Technical Update is prepared by the Technical Services Dept. of the
AFSA: Vice President of Engineering and Technical Services Roland
Huggins, a PE registered in fire protection engineering; Phill Brown,
a NICET IV certified automatic sprinkler technician and NFPA
Certified Fire Protection Specialist (CFPS) and Tom Wellen, a degreed
fire protection engineering technologist. This is provided with the
understanding that the AFSA assumes no liability for this opinion or
actions taken on it and they are not to be considered the official
position of the NFPA or its technical committees.
Copyright (c) 2007, American Fire Sprinkler Association. All
Rights Reserved
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