NFPA 5000 Issues
COMMENT ON PROPOSAL NUMBER: 5000-534
5000- - (8-9.3.2.2):
SUBMITTER: Rick Thornberry
The Code Consortium Inc. / Rep. Alcan Compistes, Inc.
RECOMMENDATION:
Revise 8.9.3.2.2 as indicated below and add a new 8.9.3.2.2.1
as follows: 8.9.3.2.2 Such materials shall be capable of preventing
the passage of flame and hot gases sufficient to ignite cotton
waste where subjected to NFPA 251 time-temperature fire conditions
under a minimum positive pressure differential of 0.01 in.
(0.254 mm) of water column (2.5 Pa) for the time period at
least equal to the fire resistance rating of the floor exterior
curtain wall assembly or 30 minutes, whichever is greater.
8.9.3.2.2.1 Where the fire resistance rating of the floor
assembly is less than the time period determined in accordance
with 8.9.3.2.2, the time period shall be permitted to be not
less than the fire resistance rating of the floor assembly.
SUBSTANTIATION
The explanatory text in the proposal we are proposed to
revise by this public comment in Annex A, A.9.3.1 clearly
indicates that the problem of the exterior fire exposure resulting
from a fire breaking out of a window opening and spreading
to the floor above is likely to occur within 15-20 minutes
or less of the time from which the fire breaks out of the
window (post flashover). At that point it is possible that
the fire could spread to the adjacent story through an unprotected
exterior window opening above, thus bypassing the joint protection
provided at the intersection of the floor assembly with the
exterior curtain wall assembly. Since that may be the case,
we have proposed that the minimum duration of protection provided
by the joint protection method at that intersection should
be at least 30 minutes which provides a factor of safety.
This time will also help to prevent the spread of the fire
via the interior at the intersection of the curtain wall unit
the curtain wall has been destroyed by the exposure fire.
The breaching of the curtain wall by the fire is also likely
to occur within the first 30 minutes of fire exposure, especially
where the curtain wall is constructed of glass or light weight
metals such as aluminum panels or ACM's. Once that condition
occurs, there is no need for the joint protection material
to remain in place since the fire can directly attack the
floor above by the flame plume escaping from the building
on the floor of origin. However, for the case where the exterior
wall is provided with a fire resistance rating, we believe
it is appropriate to assure that the joint protection material
will remain in place and resist the fire penetration for a
period at least equal to that of the exterior wall, unless
the exterior wall fire resistance rating is greater than that
of the floor assembly rating. In that case, the floor assembly
rating should govern since that is the basic fire separation
element within the interior of the building for preventing
fire spread vertically from floor to floor.
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