BCAB #1933 - Determination of Grade and Building Height for an Alteration to an Existing Building

June 20, 2024

Re:  Determination of Grade and Building Height for an Alteration to an Existing Building

Project Description

The subject building is an existing unsprinklered house, constructed in 1995 as a single-family dwelling.  A rental suite was constructed in the building sometime after the initial construction without the benefit of a building permit.  The project consists of an alteration to upgrade fire safety aspects and to legalize the second suite.

The house appears to have been constructed under Part 9 of the 1992 BC Building Code and contains floor areas on four levels.  There is some evidence that the finished ground having the lowest elevation and adjoining an exterior wall was considered to be a localized depression and the building was considered to be three storeys in building height at the time of construction.

The Building Code’s determination of building height and grade does not differ between the 1992 BCBC (applicable at the time of the initial construction of the house) and the present 2024 BCBC.  There has been no information provided to the Board that Section 2.5, Equivalents, of the 1992 BCBC was applied to allow the house to be constructed under Part 9 of that Code.

Applicable Code requirements (BCBC 2024)

Sentence 1.4.1.2.(1), Division A, Defined Terms

Building height (in storeys) means the number of storeys contained between the roof and the floor of the first storey.

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.

Note A-1.4.1.2.(1) Defined Terms

Grade

Localized depressions that need not be considered in the determination of the elevation of grade include such features as vehicle and pedestrian entrances and other minor depressions that do not affect accessibility for firefighting or evacuation.

Sentence 1.1.1.1.(1), Division A, Application of this Code

(1) This Code applies to any one or more of the following:

(d) the alteration of any building . . .

Sentence 1.1.1.2.(1), Division A, Application to Existing Buildings

(1) Where a building is altered, rehabilitated, renovated, or repaired, or there is a change in occupancy, the level of life safety and building performance shall not be decreased below a level that already exists.  (See Note A-1.1.1.2.(1))

Note A-1.1.1.2.(1), Division A, Application to Existing Buildings.  (Excerpts only)  This Code is most often applied to existing or relocated buildings when an owner wishes to rehabilitate a building, change its use . . .

Whatever the reason, Code application to existing or relocated buildings requires careful consideration of the level of safety needed for that building.  This consideration involves an analytical process . . .

In developing Code requirements for new buildings, consideration has been given to the cost they impose on a design in relation to the perceived benefits in terms of safety . . .

The successful application of Code requirements to existing construction becomes a matter of balancing the cost of implementing a requirement with the relative importance of that requirement to the overall Code objectives . . .

Further information can be found. . . publications . . .

Decision being appealed (Local Authority’s position)

The finished ground at the lowest elevation adjoining an exterior wall – a driveway for vehicle entrances – extends across the entire building face.  There are no higher portions of finished ground adjoining that wall which would allow the lowest finished ground to be considered a depression.  The low ground is not localized, is not minor, and has an impact on firefighting response.  Therefore, the lowest ground is grade for the purpose of determining building height.

The building is four storeys in building height and is a Part 3 building.  An alteration to create a second suite should include the installation of the automatic fire sprinklers that should have been installed throughout the building under the relevant Part 3 requirements at the original time of construction.

Appellant's position

The house was issued a permit as a three-storey residence, the site conditions have not changed, and there have been no structural renovations since the original construction.

Fire and life safety measures exist in the second suite and some upgrades are proposed.

The building and alteration should continue to be evaluated as a three storey, Part 9 building as was originally done, and fire sprinklers are not required.

Appeal Board Decision #1933

The Board varies the decision of the local authority.

It is the determination of the Board that the building is four storeys in building height and is a Part 3 building.

An alteration to create a second suite must not reduce the level of building performance below the level that already exists.  The degree to which the building must be altered or upgraded to address the additional risk related to the creation of a second suite is a matter for evaluation and the exercise of judgement.

Reason for decision

The driveway, as presently configured, does not meet the Code description of a localized depression.  The driveway is grade, the garage level is the first storey, and the building is four storeys in building height.  The building is a Part 3 building.

Code application to existing buildings requires careful consideration of the level of safety needed for that building.  This consideration involves an analytical process similar to that required to assess alternative design proposals for new construction.  In this case Part 3, not Part 9, provides the baseline for the evaluation and analytical process.

The local authority and the appellant can undertake a process of evaluation, analysis, and exercise of judgement to conceive of a practical approach to alteration or upgrade that will address the additional risk related to creation of a second suite.  The Board takes guidance from the Code Notes and from the User’s Guide – NBC 1995, Fire Protection, Occupant Safety and Accessibility (Part 3).

Don Pedde
Chair, Building Code Appeal Board