"Understanding Your Home" by Building Inspector Mark Visser
Home Page
About Us
Fireplace/Wood Stove
Heating and Cooling
Windows and Doors
Bricks against a combustible wall do not constitute a shield unless the brick wall is spaced out from the wall by at least 1" (25 mm)

Pyrolysis warning
Wood stoves located too close to combustible materials can cause a phenomenon called pyrolysis. Over time, the heat from the stove causes a chemical change in the wood, lowering the temperature required to make it burn. For instance, a normal piece of 2"x4" will spontaneous ignite at 600 degrees F. If the wood stove or flue pipe is too close it will draw the moisture from the 2"x4". When this happens repeatedly, the piece of wood can spontaneously ignite as low as 200 degrees F. Generally this happens in 3-5 years. The wood stove can be used for years without a problem, then suddenly there is a fire.



Wood Stoves
Certification and Building Permit. Clearances. Pyrolysis.
Need more information? Use our search box

Wood stoves may be certified or listed by one of the following CA or US agencies:
CSA - Canadian Standards Association.
ULC - Underwriters Laboratories of Canada Ltd.
WHPS - Warnock-Hersey Professional Services Ltd.
EPA - Environmental Protection Agency (US)
Building permits.
Building codes regulate the installations of all solid fuel burning appliances and a building permit is required for all installations.

Flue pipe.
Only steel flue pipes are acceptable. They should be sloped upward to the chimney. The sections should be connected in such a way that condensation from the chimney will drain towards the stove. Make sure that there is enough clearance from combustible materials.
Clearances from combustible materials.
Always check the manufacturers listing plate for proper clearances from combustible materials. If there is no plate on the back of the stove it most likely is not certified and the manufacturer or building department should be consulted.
Heat shields can be mounted on the walls around the stove and on the ceiling above.

Wood stove. Side loader will take 24" logs
Heat shields are spaced out from the wall by 1" (25 mm) non-combustible spacers. Clearances may be reduced by as much as 50% when sheet metal or ceramic tiles are used, but again, check local building codes.
Hearth size and floor protection.
The local building department should be contacted about requirements regarding the hearth size and installation on combustible floors.
Chimneys are either factory built (ULC tested) or masonry with a metal or clay flue liner. Masonry chimneys need a metal or tile flue collar to accept the flue pipe.

WARNING. NEVER BURN TREATED LUMBER IN A WOOD STOVE OR FIREPLACE. 'Wolmanized' lumber contains arsenic and chromium which are highly toxic. Do not use cedar shingles for kindling, they are also treated with chemicals.
Back to Top