BCAB #1635 - Combustible Flooring Elements in Non Combustible Construction, Article 3.1.5.8.

July 18, 2007

BCAB #1635

Re: Combustible Flooring Elements in Non Combustible Construction, Article 3.1.5.8.

Project Description

The subject is a two storey multiple occupancy building (Group D and Group F) constructed under Article 3.2.2.55. or Article 3.2.2.78.

The floor assembly in question comprises of steel structural columns and beams supporting a fluted steel deck, with 1/2 in or 5/8 plywood sheathing with vinyl or carpet finish.

Reason for Appeal

Both Articles 3.2.2.55. and 3.2.2.78. require floor assemblies to be constructed as fire separations, and if of combustible construction, shall have a fire resistance rating not less than 45 min.

Appellant’s Position

The appellant considers the presence of plywood on top of fluted steel deck does not constitute combustible construction. The plywood provides substrate for flooring finish. Sentence 3.1.5.8.(4) specifically permits combustible floor finish in non- combustible construction.

Building Official's Position
The Building Official considers the proposed assembly using plywood on top of fluted steel deck to be of combustible construction and inadequate for the required 45 minute fire resistance rating.

Appeal Board Decision #1635

It is the determination of the Board that the plywood is part of the finish flooring as it does not contribute to the structural performance of the non combustible system.

George Humphrey, Chair