The use of fire-retardant-treated wood for roof assemblies in health care facilities
BY RON COTÉ
Over the last few months, health care facility operators have been busy moving from compliance with the 2000 edition of NFPA 101®, Life Safety Code®, to the 2012 edition, as a condition of participation in the CMS Medicare and Medicaid programs. CMS adopted the 2000 edition of NFPA 101 in 2003 and enforced it until late 2016. During that period, NFPA produced four new editions of the code, each replete with new and revised provisions. Health care facility operators are learning about the post-2000 provisions applicable to their buildings, including a new topic on the use of fire-retardant-treated wood (FRTW) for roof assemblies.
The health care occupancy chapters regulate building construction type to help ensure structural integrity long into a fire incident as part of a defend-in-place strategy, recognizing that patients might be harmed in the process of egressing the building. The construction requirements utilize the building construction types defined in NFPA 220, Types of Building Construction, which are abbreviated as Type I through Type V, and for which hourly fire resistance ratings of three building elements are displayed within accompanying parentheses. Take, for example, Type I (332) construction. In the numbers in parentheses, the first number, a 3, denotes the minimum fire resistance rating, in hours, of any load-bearing exterior walls; the second 3 provides the minimum rating of the structural frame, including girders and columns supporting loads for more than one floor; and the third number, a 2, specifies the minimum rating of floor-ceiling assemblies. The user then refers to NFPA 220, or consults Table A.188.8.131.52 in the 2012 edition of NFPA 101 (extracted from NFPA 220) to learn that the minimum required fire resistance rating of the roof assembly is an hour and a half.
The health care occupancy requirements relate the various construction types to the number of stories in the building. For example, an existing three-story hospital building of Type II (000) construction, sprinklered or unsprinklered, is not permitted; an existing, sprinklered, three-story hospital building of Type II (111) construction is permitted; and an existing, three-story hospital building of Type II (222) construction, sprinklered or unsprinklered, is also permitted.
An allowance for wood roofs was added to the code in 1981. It permits a building of Type I or Type II construction that provides one or more hours of fire resistance rating to its building elements—that is, numerals 1 or greater within the parentheses, like Type I (332)—to have a wood roof positioned above a noncombustible attic floor that includes not less than two and a half inches of concrete or gypsum fill. In a fire, the roof can collapse safely onto the attic floor while the patients and staff remain safe on the occupied floors below.
The code user then refers to the 2012 edition of NFPA 101 to learn of a similar provision, added to the code in 2006, permitting a building of Type I or Type II construction that provides one or more hours of fire resistance rating to the building elements to have a roofing system of FRTW, in lieu of a concrete or gypsum-filled attic floor, if the roof assembly has the requisite fire rating.
NFPA staff, in answering code questions, heard recently from code users who mistakenly believe that FRTW can be used for roof construction only in accordance with the two provisions explained above. They are missing the fact that the provisions of NFPA 220 apply in concert with the specialized construction requirements of NFPA 101.
NFPA 220, since its 2006 edition, has permitted FRTW roofing systems in Type II (222), Type II (111) and Type II (000) construction. Roofs of Type II (000) construction are not required to be fire rated. Thus, FRTW roofs are permitted for this construction type with no additional required features.
It is an interesting time for NFPA staff to be answering code questions on health care occupancies, and we look forward to assisting members during this time of transition.