BCAB 1959 - Vertical HVAC shaft servicing a single suite

Vertical HVAC shaft servicing a single suite

Project Description

The project consists of alterations to an 875m² suite at the second storey of an existing three storey building to incorporate a child daycare.  The building is three storeys, approximately 3800m² in building area, of noncombustible construction, and unsprinklered.  The remainder of the second storey is an existing office suite, and the third storey is also an existing office suite.  The first storey is a storage garage and approximately 25% of the proposed child daycare space is located above the storage garage.  The balance of the child daycare and existing office on the second storey are slab on grade.

As a part of the alteration to facilitate the change in occupancy to a child daycare, a duct will be installed from the ceiling of the second storey, which passes through the third storey, terminating at the roof of the building.  This duct only serves the child daycare space and is installed in a vertical shaft incorporating a listed fire separation providing the appropriate fire-resistance rating for the floor assembly.  

As part of the alteration to the building, it is also proposed to add a fire suppression system to the building, however this is not a subject of this appeal.

Applicable Code requirements (BCBC 2018)

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

Vertical service space means a shaft oriented essentially vertically that is provided in a building to facilitate the installation of building services including mechanical, electrical and plumbing installations and facilities such as elevators, refuse chutes and linen chutes.

Floor area means the space on any storey of a building between exterior walls and required firewalls, including the space occupied by interior walls and partitions, but not including exits, vertical service spaces, and their enclosing assemblies.

3.2.8. Mezzanines and Openings Through Floor Assemblies

Sentences 3.2.8.1.(1) and (2) Application

1. Except as permitted by Article 3.2.8.2. and Sentence 3.3.4.2.(3) , the portions of a floor area or a mezzanine that do not terminate at an exterior wall, a firewall or a vertical shaft shall

1. terminate at a vertical fire separation having a fire-resistance rating not less than that required for the floor assembly and extending from the floor assembly to the underside of the floor or roof assembly above, or
2. be protected in conformance with the requirements of Articles 3.2.8.3. to 3.2.8.8.
3. The penetration of a floor assembly by an exit or a vertical service space shall conform to the requirements of Sections 3.4., 3.5. and 3.6.

Sentences 3.6.3.1. (1) and (3) Fire Separations for Vertical Service Spaces

1) Except as provided in Articles 3.6.3.3. and 3.6.3.5. and Section 3.5., a vertical service space shall be separated from all other portions of each adjacent storey by a fire separation having a fire-resistance rating conforming to Table 3.6.3.1. for the fire-resistance rating required by Subsection 3.2.2. for

1. the floor assembly above the storey, or
2. the floor assembly below the storey, if there is no floor assembly above.

(See Note A-3.6.3.1.(1) .)

3) A vertical service space that does not extend to the bottom of a building shall be enclosed at the lowest level with construction having a fire-resistance rating not less than that required for the vertical service space walls.

Decision being appealed (Local Authority’s position)

The shaft installed meets the definition of a vertical service space and therefore is excluded from the floor area of the child daycare space.

Sentence 3.2.8.1.(2) deals with penetration of a floor assembly by a vertical service space specifically.  This sentence clarifies that a penetration of a floor assembly by a vertical service space shall conform to the requirements of Sections 3.4., 3.5. and 3.6.

Sentence 3.6.3.1.(1) states that a vertical service space shall be separated from all other portions of each adjacent storey by a fire separation having a fire-resistance rating conforming to Table 3.6.3.1.  For a 1 h floor assembly, Table 3.6.3.1. requires a minimum fire-resistance rating of 45 min for the vertical service space.  Providing a 1 h fire-resistance rating for the vertical service space is better, however it does not eliminate the additional protection required by Sentence 3.6.3.1.(3).

Sentence 3.6.3.1.(3) states that “…. a vertical service space that does not extend to the bottom of a building shall be enclosed at the lowest level with construction having a fire-resistance rating not less than that required for the vertical service space walls.”

Appellant's position

The shaft installed is part of the floor area of the second storey fire compartment and services only the child daycare.

There are no openings from the shaft to the third storey office suite and it is simply an extension of the second storey floor area (the child daycare suite).  As the duct is always within a single fire compartment, no fire/smoke damper is required.

The proposed design complies with Sentence 3.2.8.1.(1).  The floor area of the office space on the third storey terminates at the vertical fire separation (the vertical shaft) having the same fire-resistance rating as the floor assembly which is 1 h.  The shaft extends to, and terminates at, the roof of the building.

Appeal Board Decision #1959

The Board reverses the decision of the local authority.

It is the determination of the Board that the vertical shaft forms part of the floor area and is an extension of the proposed child daycare, and as such complies with the requirements of Clause 3.2.8.1.(1)(a), Division B.

Reason for decision

The proposed mechanical duct services only the child daycare and does not serve any other suites.  There are no openings in the vertical shaft walls that would interconnect with the other suites and the vertical shaft terminates at the roof of the building.

Doug Vance
Acting Chair, Building Code Appeal Board

Dated:  April 17, 2025