2024 Ontario Building Code Changes

Ontario is creating a new 2024 Ontario Building Code that comes into effect January 1, 2025.

There are hundreds of minor changes with wording but here is a summary of some of the changes that residential contractors are most likely to run into.

Secondary suites:

Many changes have been made to differentiate secondary suites in a house from suites in apartment buildings. These apply only to a ‘house’ with no more than 2 units. A house means detached, semi-detached, or row house but does not include a stacked townhouse. Here are a few major changes:

·         A fire separation is not required for a secondary suite. Instead a continuous smoke-tight barrier of 5/8” type ‘X’ gypsum can be used on the basement ceiling and on both sides of dividing walls. This should simplify protrusions through this barrier as it does not need to align with fire separation rules. A fire separation is still acceptable

·         Lower ceiling heights allowed in secondary suites (6’-5” main ceiling and 6’-0” below bulkhead). This aligns closer with building older than 5 years requirements

·         Wireless connection between smoke alarms between units in homes older than 5 years is allowed (not allowed in new homes). Smoke alarms are required to be connected between units with shared ventilation equipment.

·         Requirements have been placed on sharing a furnace with the secondary suite in a house: (9.33.1.1.(3)“Air duct distribution systems serving one of the dwelling units in a house with a secondary suite shall not be directly interconnected with other parts of the house”) This is slightly vague and some municipalities may require a completely separate furnace while others might allow separate ducting for each unit. Houses older than 5 years can still interconnect the furnace system when adding an apartment.

Radon Gas:

Soil gas control guidelines have been expanded to include soil gas control for all regions and a required rough-in for subfloor depressurization. Every slab on grade will now require a 4” pipe extending from the gravel layer through the slab and clearly labeled for radon extraction. This pipe below the slab needs to end with an open end “at or near the center of the slab” but can be laid under the concrete and come up anywhere above the slab with a permanently sealed cap.

Stairs & Guards:

·         Open riser stairs are now only allowed in houses (some exceptions for fire escape & maintenance service stairs apply)

·         The triangle formed between the stair tread, riser, and the bottom of the guardrail cannot allow a 6” sphere to pass through.

Fire Protection

Code rules surrounding penetrations in a fire separation have been re-written with more individual rules for each type of penetration through a fire separation. Outlet boxes, piping, and sprinklers all have individual code articles to provide more clarity.

Heating and Ventilation:

Many changes have been made to heating and ventilation requirements to harmonize with the National Building Code. This may cause more municipalities to require duct design for all homes. Requirements don’t seem much different, but the wording and code layout has changed significantly. Here are some updated requirements:

·         Exterior air supply requirements have increased to mitigate negative air pressure in buildings.

·         100 cfm exhaust in kitchens (some exemptions apply)

·         CO alarm requirements are expanded to more areas than before

·         Exterior air intakes must be 6’ from gas vents and high moisture exhausts (bath fan & dryer vents)

·         High moisture exhausts in soffits shall have unvented or blocked soffit 6’ each side of the exhaust

·         High moisture exhausts installed less than 6’ below soffits shall have unvented or blocked soffits according to this table:

Tiny Homes:

New regulations for tiny homes (188ft² - 400ft²) have been added to the building code. Be aware that for mobile tiny homes a permit is required in the municipality where it is built and also in the municipality it is installed in.

Farm buildings:

A completely new section of the Code has been created for farm buildings. Different rules apply depending on size of building, hazards in the building, human occupant load etc. The huge range of modern agricultural buildings needed an updated approach to prescriptive design standards.