BCAB #1893

July 21, 2022

Re: Required Fire Blocking

Project Description

The project is a single dwelling residential building (house) constructed under Part 9 of the BC Building Code. The structure utilizes Insulated Concrete Form (ICF) walls. The ICF walls have an interior finish of gypsum board directly attached to the ICF rigid insulation. There is no air space between the back of the gypsum board and the face of the rigid insulation, except for very minimal areas to accommodate wiring or electrical boxes within the insulation. There is a drop ceiling creating a horizontal concealed space, the underside finished with gypsum board, that intersects within the ICF exterior wall. There is exposed foamed plastic above the drop ceiling.

Applicable Code requirements: (BCBC 2018)

9.10.16.1. Required Fire Blocks in Concealed Spaces

1) Vertical concealed spaces in interior walls and exterior walls shall be separated     by fire blocks

a) one from the other, and

b) from horizontal concealed spaces.

2) Horizontal concealed spaces in attics, roof spaces, ceilings, floors, and crawl spaces shall be separated by fire blocks

a) one from the other, and

b) from vertical concealed spaces.

3) Fire blocks shall be provided at all interconnections between concealed vertical and horizontal spaces in interior coved ceilings, drop ceilings and soffits where the exposed construction materials within the concealed spaces have a surface flame-spread rating greater than 25.

9.10.16.2. Required Fire Blocks in Wall Assemblies

1) Except as permitted in Sentence (2), fire blocks shall be provided to block off concealed spaces within wall assemblies, including spaces created by furring,

a) at each floor level,

b) at each ceiling level where the ceiling contributes to part of the required fire-resistance rating, and

c) at other locations within the wall, so that the distance between fire blocks does not exceed 20 m horizontally and 3 m vertically.

9.10.16.2. Required Fire Blocks in Wall Assemblies (cont.)

2) Fire blocks described in Sentence (1) are not required, provided

a) the insulated wall assembly contains not more than one concealed air space whose horizontal thickness is not

more than 25 mm,

b) the exposed construction materials within the space are noncombustible,

c) the exposed construction materials within the space, including insulation, but not including wiring, piping or

similar services, have a flame-spread rating of not more than 25, or

d) the concealed wall space is filled with insulation.

9.10.17.10. Protection of Foamed Plastics

(See Note A-3.1.4.2.)

1) Except as provided in Sentences (2) and (3), foamed plastics that form part of a wall or ceiling assembly shall be protected from adjacent space in the building, other than adjacent concealed spaces within attic or roof spaces, crawl spaces, wall assemblies and ceiling assemblies

a) by one of the interior finishes described in Subsections 9.29.4. to 9.29.9.,

b) provided the building does not contain a Group C major occupancy, by sheet metal that

i) is mechanically fastened to the supporting assembly independent of the insulation,

ii) is not less than 0.38 mm thick, and

iii) has a melting point not less than 650°C, or

c) by any thermal barrier that meets the requirements of Sentence 3.1.5.15.(2).

(See Note A-3.1.4.2.(1)(c).)

Decision being appealed (local authority’s position)

The local authority considers when the interior finish of gypsum board is installed, a vertical concealed space is created. The local authority has determined that fire blocking is required in conformance with Sentence 9.10.16.1.(3) to separate the vertical concealed space in the wall from the horizontal concealed space in the drop ceiling.

Appellant's position

The appellant considers that Sentence 9.10.17.10.(1) permits foamed plastics that forms part of a wall need not be protected from adjacent spaces within ceiling assemblies.

Appeal Board decision #1893

It is the determination of the Board that the installation of gypsum board directly onto the rigid insulation of the ICF wall does not create a vertical concealed space and therefore the requirements of Sentence 9.10.16.1.(3) are not applicable. 

Reason for decision

The Board considers the addition of gypsum board onto an ICF wall maintains a monolithic assembly without voids. The risk of fire spread within the assembly is not that of a wall assembly that has a concealed space.

Lyle Kuhnert

Chair, Building Code Appeal Board