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BCC Ruling No. 94-19-397

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IN THE MATTER OF Subsection 24(1) of the Building Code Act, 1992.

AND IN THE MATTER OF Sentences of Revised Regulation of Ontario 1990, Regulation 61, as amended by O.Regs. 400/91, 158/93 and 160/93 (the "Building Code").

AND IN THE MATTER OF an application by Bradscot Northern Construction for the resolution of a dispute with Mr. Ivan Wilson, Chief Building Official, Township of Mariposa.


Bradscot Northern Construction


Mr. Ivan Wilson
Deputy Chief Building Official
Township of Mariposa


Sarah Maman, Chair
Rick Florio
David Lam


Toronto, Ontario


July 21st, 1994


Mr. Gary Chu
Dow Chemical Canada Inc.,

For the applicant

Mr. Fraser MacDonald
Chief Building Official
Township of Ops


  1. The Applicant

Bradscot Northern Construction are holders of a permit under the Building Code Act, 1992 to construct an elementary school in the hamlet of Little Britain, Township of Mariposa.

  1. Description of Constrution

The applicant is constructing an elementary school which is classified as a Group A, Division 2 major occupancy. The exterior wall of the building is comprised of 190 mm concrete block, 90 mm styrofoam Cavitymate insulation, 20 mm air space and 100 mm of brick veneer.

  1. Dispute

The dispute between the Applicant and Respondent concerns sufficiency of compliance with Sentences of the Building Code. At issue is the requirement to fire stop the 20 mm concealed space in the exterior wall assembly.

  1. Provision of the Building Code

Sentences Fire Stopping in Wall Assemblies (1) Except as permitted in Sentence (2), fire stops conforming to Article shall be provided to block off spaces within a wall assembly: (a) at every floor level; (b) at every ceiling level where the ceiling forms part of an assembly required to have a fire-resistance rating; and, (c) so that the maximum horizontal dimension is not more than 20 m and the maximum vertical dimension is not more than 3 m. (2) Fire Stopping conforming to Sentence (1) are not required provided: (a) the wall space is filled with insulation; (b) the exposed construction materials and any insulation within the wall space are noncombustible; or, (c) the exposed construction materials and any insulation within the wall space have a flame-spread rating of not more than 25 on any exposed surface or on any surface that would be exposed by cutting through the material in any direction and fire stops are installed so that the vertical distance between them does not exceed 10 m.

  1. Applicant's Position

The applicant provided the following information to demonstrate sufficiency of compliance with the fire stopping requirements for concealed spaces within the wall assembly: (1) Sentence of the National Building Code of Canada (NBCC) was amended January 1993 by an additional exception to the fire stopping requirement: "(d) the insulated wall assembly contains not more than one concealed air space, and the horizontal thickness of that air space is not more than 25 mm."; (2) The Building Code Commission ruled in favour of a similar application on December 20, 1993 (i.e. R93-21-377); (3) The Flame Spread Classification determined by CAN/ULC S102.2- M88 is ineffective for fire stopping requirements because field conditions differ from the test and poor reproducibility of test results; and, (4) Research indicates that ventilation in the concealed space influences the spread of fire. Therefore, the concealed space must have an adequate supply of oxygen for combustion. The critical width of the concealed space was said to be approximately 25 mm.

  1. Chief Building Officials Position

The respondent stated that the Building Code clearly requires fire stopping in the wall assembly. Concern was expressed about the potential spread of fire within the wall cavity and the difficulty this could present to fire fighters trying to extinguish the fire.

  1. Commission Ruling:

In favour of the Applicant. It is the decision of the Building Code Commission that insulation in excess of a 25 flame spread rating within the wall space of a building with no fire stopping, provided that there is only one concealed air space that is not more than 25mm thick, shows sufficiency of compliance with the Building Code.

  1. Reasons:

    1. Tests conducted at the National Research Council indicated that the thickness of the air space is the critical factor in determining flame spread in a wall cavity. 2. An emergency amendment to the fire stopping requirement in the National Building Code was approved in 1993, based on the tests conducted at the National Research Council. 3. The building is a one storey school, occupied by well trained staff who would immediately react to any fire condition.

Dated at Toronto, this 21st day, in the month of July, in the year 1994, for application number 1994-29.

Sarah Maman

Rick Florio

David Lam