What are Toronto's building code requirements for drywall around a wood-burning fireplace or stove?

Drywall around a wood-burning fireplace or stove must maintain specific clearance distances and use fire-rated materials as required by the Ontario Building Code and CSA B365 (Installation Code for Solid-Fuel-Burning Appliances and Equipment). The exact requirements depend on the type of appliance, its listing and certification, and whether you're dealing with a factory-built fireplace, a masonry fireplace, or a freestanding wood stove.

The fundamental rule is that standard drywall — even 5/8-inch Type X — cannot be in direct contact with a wood-burning appliance or its chimney connector (stovepipe). Drywall is a combustible material for the purposes of clearance requirements because the paper facing can ignite. The required clearances between a wood-burning appliance and combustible materials (including drywall) are specified by the appliance manufacturer and enforced by the Ontario Building Code. Typical minimums are 36 inches (900mm) from a single-wall stovepipe to combustible walls and 18 inches (450mm) from a double-wall insulated stovepipe, though manufacturer specifications may differ.

For the wall and ceiling areas within the clearance zone, you have several options that the building code and WETT (Wood Energy Technology Transfer) inspectors will accept. A non-combustible wall shield can be installed to reduce the required clearances — this typically involves mounting cement board, sheet metal, or a manufactured heat shield on non-combustible spacers that create a minimum 1-inch (25mm) air gap behind the shield. The air gap is critical because it allows air to circulate behind the shield, preventing heat buildup that could ignite the wall framing and drywall behind it. The shield must extend beyond the appliance on all sides by the distance specified in the manufacturer's installation manual.

Fire-Rated Assemblies Near Fireplaces

For factory-built (zero-clearance) fireplaces, the manufacturer's installation instructions are the governing document. These fireplaces are tested and listed to specific standards (ULC S610 in Canada), and the installation manual specifies exactly what materials can be used around the unit and at what distances. Most factory-built fireplaces allow standard drywall on the surrounding wall at specified clearances (typically 0–2 inches from the fireplace cabinet, depending on the model), with a non-combustible mantel clearance specified separately. A building inspector in Toronto will check that the installation matches the manufacturer's listing exactly — any deviation voids the listing and creates a fire hazard.

For masonry fireplaces, the Ontario Building Code requires that the firebox be constructed of fire brick and refractory mortar, surrounded by a minimum 2-inch air space between the masonry and any combustible framing or drywall. The hearth extension must project at least 400mm (16 inches) in front of the fireplace opening and 200mm (8 inches) beyond each side. Drywall on the wall above and beside the fireplace must maintain these clearances from the masonry structure.

For freestanding wood stoves, the clearance requirements are the most significant concern for drywall installers. The area behind and beside the stove typically requires a wall protection system — this is not just extra drywall, but a dedicated non-combustible assembly with proper air spacing. Simply adding a second layer of drywall does not meet code requirements because drywall's paper facing remains combustible.

The chimney penetration through the ceiling is another critical area. Where the chimney passes through a ceiling, a manufactured ceiling support box (firestop) is required, maintaining the specified clearances to all combustible materials including drywall and framing. The drywall must be cut to the exact specifications of the ceiling support box — too tight and you risk combustible material within the clearance zone, too loose and you have an unsealed penetration.

Building permits are required for all wood-burning appliance installations in Toronto, and a WETT-certified inspector should inspect the completed installation. The permit ensures that all clearances, materials, and installation details meet code. For drywall contractors, the key takeaway is that drywall around wood-burning appliances isn't standard framing-and-boarding work — it requires careful coordination with the appliance installer to maintain proper clearances and use appropriate materials where required. The cost for drywall work around a wood stove or fireplace installation typically runs $500–$2,000 depending on the scope, clearance requirements, and finish level.

If you're planning a wood-burning appliance installation or renovation around an existing fireplace, find a drywall contractor experienced with fire-rated assemblies through the Toronto Construction Network directory at torontoconstructionnetwork.com/directory?trade=insulation.