BCAB #1724 - Continuity of a Fire Separation, Articles 9.10.9.2. & 9.10.9.10.

March 04, 2013

BCAB #1724

Re: Continuity of a Fire Separation, Articles 9.10.9.2. & 9.10.9.10.

Project Description

The project in question is a secondary suite being constructed in an existing house. The issue at appeal is how to construct the intersection of a fire separation wall and the fire separation floor assembly above. The wall and floor are standard wood frame construction and the floor joists run at right angles to the wall.

Reason for Appeal

Article 9.10.9.2. requires a fire separation to be constructed as a continuous barrier against the spread of fire and retard the passage of smoke. The continuity of a fire separation shall be maintained where it abuts another fire separation, a floor, a ceiling, a roof, or an exterior wall assembly. The related appendix note says that the continuity of a fire separation where it abuts against another fire separation, a floor, a ceiling or an exterior wall assembly is maintained by filling all openings at the juncture of the assemblies with a material that will ensure the integrity of the fire separation at that location.

Appellant's Position

The appellant contends that filling the joist spaces of the floor assembly over the area of the secondary suite with mineral fibre insulation (rock wool) maintains the integrity or continuity of the fire rated wall where it meets the fire rated floor assembly above it.

Building Official's Position

The building official maintains that as per past practice it is necessary to use solid wood blocking in the joist spaces above the fire rated wall to maintain the continuity of the fire separation through to the underside of the floor sheathing. Building Code Interpretation Committee interpretation 06-0014b is cited to support this opinion. The use of mineral fibre insulation would be considered an alternate solution in the opinion of the building official.

Appeal Board Decision #1724

Article 9.10.9.2. deals with the intersection of the floor and wall assemblies. It is the determination of the Board that Article 9.10.9.10. deals with the concealed space within the floor assembly above the vertical fire separation. Article 9.10.9.10. offers two options; either an equivalent vertical fire separation is maintained through the floor assembly or the fire separation is maintained horizontally at both sides of the vertical fire separation such as per assembly M1 in Table A-9.10.3.1.B. in Appendix A of Division B. The Board considers that mineral wool insulation does not provide an equivalent fire separation through a concealed space per the first option above (9.10.9.10.(1)).

George Humphrey, Chair