Ontario Wood Stove Clearance Calculator
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Minimum Required Clearance
Floor Protection Rule: Your non-combustible floor pad must extend at least 18 inches in front of the loading door, and 8 inches beyond the sides and rear.
Certified vs. Uncertified Stoves: The 48-Inch Rule
When determining how close you can safely place your wood stove to a combustible wall, the very first step is checking for a certification label. If your stove has a ULC, CSA, or EPA metal tag bolted to the back, it is "Certified." You must follow the exact side and rear clearances printed on that label. If you are still choosing an appliance, start with the Wood Stove BTU Sizing Calculator so you know the heat output range before planning clearances.
However, if your stove is older, or if the metal tag has been removed or painted over, it is legally considered Uncertified. Uncertified stoves have not passed modern safety tests and burn much hotter, meaning they require massive installation clearances. Under the CSA B365 installation code, an uncertified radiant stove must sit a full 48 inches (1200 mm) away from any combustible wall. Because 48 inches takes up a massive amount of living space, almost every homeowner needs to utilize clearance reduction strategies.
How to Safely Reduce Your Wall Clearance
You can safely reduce the required clearance distance by installing a proper heat shield, but it must be done strictly according to the CSA B365 standard.
The most important feature of any clearance shield is the air space. The shield must be spaced out from the wall by at least 7/8 of an inch (typically 1 inch) using non-combustible spacers. There must also be a 1-inch to 3-inch gap at the bottom and top of the shield to allow air to flow vertically. This convection flow is what actually keeps your drywall safe.
If you follow these rules, you can reduce your required clearance by:
- 67% using a minimum 29-gauge sheet metal shield.
- 50% using ceramic tile or brick veneer.
Don't Forget Your Floor Pad Protection
Wall clearances are only half the battle. Your non-combustible floor pad (or hearth extension) must also meet strict size requirements to protect your home from falling embers. In Canada, your floor pad must extend at least 18 inches (450 mm) in front of the loading door, and 8 inches (200 mm) beyond the sides and rear of the appliance. If you are installing a heavy uncertified stove, the floor pad rules become even more complicated depending on the height of the stove legs. Before you light your first fire, ensure your math is correct by booking a certified professional.
Frequently Asked Questions
Can I just glue brick or tile directly to my drywall to protect it?
No. A non-combustible wall must be made of non-combustible materials throughout the entire wall assembly (like a solid concrete wall). Gluing brick or tile directly to wood-framed drywall does not count as a heat shield because there is no air gap. Without that 1-inch air gap, the heat conducts right through the brick and can easily ignite the drywall behind it.
My insurance company is asking for a WETT Certificate for my uncertified stove. What do I do?
First, know that a "WETT Certificate" does not actually exist-your insurer is simply asking for a formal Inspection Report. Second, be aware that while some insurers will cover uncertified stoves if they perfectly meet the 48-inch CSA B365 clearances, many modern insurance companies will flat-out refuse to insure uncertified wood stoves.
Does my single-wall flue pipe need clearances too?
Yes. Uncertified single-wall flue pipe generally requires an 18-inch clearance from combustible walls and ceilings. Just like the stove, this distance can be reduced by 50% if you install a proper sheet metal shield with an air gap.