BCAB #1637 - Scissor Stairs, Fire Separation Continuity, Sentence 3.4.4.4.(2) and (3) Division B

October 24, 2007

BCAB #1637

Re: Scissor Stairs, Fire Separation Continuity, Sentence 3.4.4.4.(2) and (3) Division B

Project Description
The subject building is a high rise residential building, fully sprinklered, non combustible construction, and incorporates contiguous scissor stairs for its exiting system. Standpipe hose connections are provided in the scissor stair exits in conformance with Article 9.25.10, and NFPA 14, “Installation of Standpipes and Hose Systems”.

The contiguous scissor exit stairs are located in a shaft which separates the exits from the remainder of the building by a fire separation with a 2 hour fire resistance rating. The contiguous scissor stairs are separated from each other by fire separations with a 2 hour fire resistance rating.

Directly adjacent (and attached) to the exit shaft is a vertical service space (shaft) with its walls constructed as fire separations with a 2 hour fire resistance rating. This vertical service space encloses the required standpipe and other building services i.e. HVAC duct and other piping. The duct within this vertical service space has openings on each floor of the shaft wall on the corridor side for grills. The grille openings will be protected with a fire damper with a 1 ½ hr fire protection rating.

The hose connections from the standpipe into the exit shaft are appropriately firestopped to maintain the continuity of the exit shaft wall fire separation.

Reason for Appeal
Sentence 3.4.4.4.(2) requires exits within scissor stairs to be separated from each other by a smoke-tight fire separation having a fire-resistance rating not less than that required for the floor assembly which they pass.

Sentence 3.4.4.4.(3) states that fire separations separating contiguous stairs shall not be pierced by piping or other openings that affect the continuity of the separations.

Appellant’s Position
The appellant considers the standpipe is outside the exit enclosure in a vertical service space constructed with the same fire resistance rating required for the exits. The only penetrations into the exit stair shaft will be hose connections serving each landing of the exit stair.

Building Official's Position
The Building Official considers due to the commonality between the vertical service space and the exit stairs that the hose connection penetrations at each floor create a potential opening between the two stairs via the shaft. Further NFPA 14 states standpipes and lateral piping supplied by standpipes shall be located in enclosed exit stairways or shall be protected by a degree of fire resistance equal to that required for enclosed exit stairways in the building in which they are located. With the standpipe sharing the vertical service space with a duct having grille openings protected with 1 ½ hour fire protection rated closures, the degree of fire resistance rating is not equal to that required for the enclosed exit stairway.

Appeal Board Decision #1637
It is the determination of the Board that where a standpipe is located in a vertical service space (shaft) separated from the exit enclosure, the shaft shall not contain any building services other than the standpipe.

George Humphrey, Chair