BCAB #1575 - Fire Separation Construction for Duplex Conversion, Sentences 9.10.3.1.(1), 9.10.3.3.(3) & 9.10.9.14.(3)

December 18, 2002

BCAB #1575

Re: Fire Separation Construction for Duplex Conversion, Sentences 9.10.3.1.(1), 9.10.3.3.(3) & 9.10.9.14.(3)

Project Description

The project in question is the conversion of an existing single family dwelling to a duplex. An existing exterior wall will become one half of the fire separation separating the two dwelling units. The existing wall is 12 mm (1/2") regular gypsum board on wood studs with shiplap and 19 mm of stucco. It is proposed to construct a new wall, 1 1/2" away from the existing, which would have 16 mm (5/8") Type ‘X’ gypsum board on both sides of wood studs. The new construction is structurally independent of the existing building.

Reason for Appeal

Sentence 9.10.9.14.(3) requires suites of residential occupancy that contain more than one storey to be separated by a fire separation with a fire resistance rating of 1 hour. Sentence 9.10.3.3.(3) requires interior vertical fire separations to be rated for fire exposure from both sides. Where a fire resistance rating is required Sentence 9.10.3.1.(1) requires it to be determined in accordance with Part 3, A-9.10.3.1. in Appendix A or Appendix D.

Appellant’s Position

The appellant contends that the proposed suite separation wall will provide the required 1 hour fire resistance rating. The new wall will provide all of the required rating while the existing wall will effectively increase the fire resistance rating between the two suites.

Building Official's Position

The building official maintains that the interior face of the existing wall must be upgraded by the application of 16 mm Type ‘X’ gypsum board in order to provide the required 1 hour fire resistance rating. The most likely location for a fire is within a room on either side of the double stud wall and the most fire resistant component of the assembly should be at the face of the wall assembly, not near the middle.

Appeal Board Decision #1575

It is the determination of the Board that the proposed fire separation between the new and existing dwellings provides the 1 hour fire resistance rating required by Sentence 9.10.9.14.(3). The new and existing walls creating the fire separation between the two suites provide more than the required fire resistance rating.

George Humphrey, Chair