July 16, 2020
Re: Establishing Finished Ground for the Determination of Grade for a Storage Garage
The project is two residential sprinklered combustible buildings (825 m2, 1450 m2) to be built over a common storage garage building (4570 m2). As permitted by Article 188.8.131.52., it is proposed that the storage garage be considered a basement and separate building for the purpose of determining building height and establishing individual buildings.
Due to building site conditions, in order that the storage garage be considered a basement, it is proposed access stairs, ramps and tiered earth areas up to 2 m high, be constructed or retained against the walls of the storage garage to establish finished ground. The tiered earth widths are not less than 1.2 m.
The storage garage fronts onto a public roadway. All required firefighting access for the residential buildings above the storage garage is by vehicular access onto the podium/roof of storage garage.
The two residential buildings constructed under 184.108.40.206. have not less than 10% of their building perimeter within 15 m of the firefighting access route.
Applicable Code Requirements
Definitions of basement, first storey, and grade in Article 220.127.116.11 of Division A of the British Columbia Building Code 2018.
Basement means a storey or storeys of a building located below the first storey.
First storey means the uppermost storey having its floor level not more than 2 m above grade.
Grade means the lowest of the average levels of finished ground adjoining each exterior wall of a building, except that localized depressions need not be considered in the determination of average levels of finished ground. (See First storey and Note A-18.104.22.168.(1).)
Sentence 22.214.171.124.(1) of Division B of the British Columbia Building Code 2018.
126.96.36.199.(1) A basement used primarily as a storage garage is permitted to be considered as a separate building for the purposes of Subsection 3.2.2. and Sentences 188.8.131.52.(2) and (3), provided the floor and roof assemblies above the basement and the exterior walls of the basement above the adjoining ground level are constructed as fire separations of noncombustible construction having a fire-resistance rating not less than 2 h and protected in conformance with Clause 184.108.40.206.(4)(a), except as permitted by Sentence (2). (See Notes A-220.127.116.11.(4) and A-18.104.22.168.(2).
Decision being Appealed (Local Authority’s Position)
The local authority has determined that the storage garage is not a basement in that grade is based on both existing and proposed finished grades as they relate to the property. The local authority has determined grade based on the Building Code and the NBC Users Guide. The local authority considers fire-fighting capabilities are impacted by the appellant’s artificially interpreted grade calculations.
The appellant maintains that given the site conditions of the proposed building(s), the use of proposed tiered earth areas adjacent the storage garage walls to raise the level of finished ground such that the storage garage can be considered a basement is acceptable.
Appeal Board Decision #1848
It is the determination of the Board that in this specific circumstance, grade can be determined from finished ground that is artificially established by tiered earth areas constructed or retained against the walls of the storage garage.
Reason for Decision
The designed access for firefighting for these particular buildings are from the podium level. When considering any other project or specific site, all of those conditions must be taken into account. For the determination of grade, the analysis must be site specific.
The Board acknowledges local government land use bylaws may have other criteria for determining grade or building height, but these are for objectives other than those of the Building Code.
The Board is not approving specific calculations for the subject Appeal, such as determining localized depressions or establishing averages, but rather ruling on the permission to artificially establish finished ground.
The Board has used guidance from the 1995 NBC User’s Guide indicating “If the effect of grading is to reduce the internal fire safety measures, care has to be taken that the occupants are not exposed to an increased risk. Therefore, reason and judgement must be exercised in establishing grade, taking into account exiting and fire-fighting.” The Board considers it is necessary to demonstrate that the effect of grading does not put the occupants of the building at a greater risk.
This is consistent with the decision of Appeal #1291 which states: “It is the determination of the Board that the definition of "grade" clearly refers to finished ground which allows the existing grade to be altered by fill and excavation, with "building height" measured from the finished grade.”
Chair, Building Code Appeal Board