BCAB 1987 - Ventilation requirements in the renovation of a guest suite in an existing building

Ventilation requirements in the renovation of a guest suite in an existing building

Project Description

The project is the renovation of one guest suite within an existing Part 9 building containing three self-contained guest suites of tourist accommodation and one caretaker’s suite.

Ventilation in the guest suites is provided by operable windows.  Heating is provided by electric radiant heaters.

The guest suite undergoing the renovation is arranged over two storeys.  The first level contains a kitchen, a bathroom, and a living area.  The pre-renovation upper storey contained a bedroom, a bathroom, and an open floor area.  The renovation plan includes new walls in the open floor area to create three additional enclosed bedrooms.  At the time of application, most of the interior finishes in the suite had been removed.

The lodge functions as a seasonal-use facility, operating from May through October.  The average daily high and low temperatures in the region are approximately as follows:

• May - high 17^o C, low 4^o C, and
• October - high 10^o C, low 0^o C.

Applicable Code requirements (BCBC 2024, Revision 6)

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).)

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

 . . . 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 similar to that required to assess alternative design proposals for new construction.  See Clause 1.2.1.1.(1)(b) for information on achieving compliance with the Code using alternative solutions.

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 former is definable; the latter difficult to establish on a quantitative basis.  In applying the Code requirements to an existing building, the benefits derived are the same as in new buildings.  On the other hand, the increased cost of implementing in an existing building a design solution that would normally be intended for a new building may be prohibitive.

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.  The degree to which any particular requirement can be relaxed without affecting the intended level of safety of the Code requires considerable judgment on the part of both the designer and the authority having jurisdiction.

Sentences 9.32.1.2.(1 and 2), Division B, Required Ventilation

(1) Every dwelling unit shall incorporate

(a) provisions for non-heating-season ventilation in accordance with Subsection 9.32.2., and

(b) except as required by Sentences (2) and (3), if supplied with electrical power, provisions for heating-season ventilation in accordance with Subsection 9.32.3.

(2) A self-contained heating-season ventilation system serving a single dwelling unit or a house with a secondary suite including their common spaces shall comply with Subsection 9.32.3. (See Note A-9.32.1.2.(2).)

Sentence 9.32.2.1., Division B, Required Ventilation (Non-Heating-Season)

(1) Rooms or spaces in dwelling units shall be ventilated during the non-heating season by

(a) natural ventilation in accordance with Article 9.32.2.2., or

(b) a mechanical ventilation system conforming to Subsection 9.32.2.3. [sic].

Sentence 9.32.3.1., Required Ventilation (Heating-Season Mechanical)

(1) Every dwelling unit that is supplied with electrical power shall be provided by a mechanical ventilation system that conforms to

(a) CAN/CSA-F326-M, "Residential Mechanical Ventilation Systems,"

(b) this Subsection, or

(c) for ducted mechanical ventilation systems serving more than one dwelling unit in a house with a secondary suite including their common spaces, the mechanical ventilation system shall comply with this Subsection or Part 6.

(See Note A-9.32.3.1.(1).)

Decision being appealed (Local Authority’s position)

The creation of new bedrooms increases the number of people exposed to the existing, non-conforming ventilation condition, representing a reduction in the level of building performance.

The guidance provided in Note A-9.1.1.1.(1) does not indicate that seasonally occupied buildings are exempt from ventilation requirements.

Finishes have been removed and framing exposed; installation of a compliant ventilation system does not appear to be impractical.  Non-heating season natural ventilation and heating season mechanical ventilation are required.

Appellant's position

The lodge is 73 years old.  The natural ventilation provided by operable windows has been adequate for decades and satisfies the intent of the Code requirements in a seasonally occupied building.

The guest suite contains no propane or natural gas appliances so there are no emissions-related needs for ventilation.  Given the building’s age, design limitations, and operational use, installing a ventilation system would be structurally invasive, cost-prohibitive, and inconsistent with the character and function of the building.

Appeal Board Decision #1987

The Board confirms the decision of the local authority.

It is the determination of the Board that non-heating season natural ventilation and heating season mechanical ventilation are required in the three new enclosed bedrooms.

Reason for decision

The Board considers that the seasonal use of the building begins in the heating season, continues through the non-heating season, and ends in the heating season.

The project is the alteration of an existing building and the current code requirements regarding natural and mechanical ventilation apply to the altered areas.  However, full implementation of a new Code requirement in the existing building may be difficult.  The Code permits the application of a cost benefit analysis and, due to those difficulties, the installation may not fully meet all provisions.  The degree to which the ventilation requirement can be relaxed without affecting the Code’s intended level of building performance requires considerable judgment on the part of both the owner and the local authority.

Don Pedde
Chair, Building Code Appeal Board

Dated:  November 6, 2025