Wood Stove Installation Clearances
Standard Installation Clearances
Installation of a wood stove is typically a job that is best left to the professionals. Before installing a wood stove, seek advice from your wood stove dealer, your local building inspector or fire department. You’ll also need to check with your insurance agent. Your insurance provider may have its own specifications for installation and, since you will be changing the method of heating your home, your insurance agent must be notified in order to maintain fire insurance coverage on your home.
Standards have been developed by the National Fire Protection Association (NFPA) for wood stove clearances from walls and ceilings that are the basis for many local building codes. The basic clearances are as follows:
All combustible materials such as woodwork, unprotected walls, furniture, firewood, etc., should be at least 36 inches away from your wood stove. A stove pipe should be at least 18 inches away from an unprotected ceiling.
Wood that is continually reheated will ignite at much lower temperatures than fresh wood so these distances should be adhered too diligently. For instance, a new wall will begin burning at between temperatures between 500 and 700 degrees F, whereas a wall that is continually heated over a period of time will dry and the ignition temperature can drop to as low as 200 to 250 degrees F (a good reason to avoid cutting corners.)
Wall Protection Clearances
Here’s a quick test that will tell you if you have enough clearance to an unprotected wall. Put your hand on the nearest surface. If you can comfortably keep your hand there while the stove is operating, the location passes the test. If not, the wall needs additional protection.
Protection for the wall can be achieved by spacing either asbestos millboard or 28 gauge steel 1-inch away from the wall. This will allow you to reduce the distance between the stove and wall. These materials are designed to absorb heat that is radiated from the stove and the spacing in between the wall and the protective material lets air circulate behind the panel and cool the area in between. Spacers should be made of non-combustible material. A 1 to 1 1/2-inch gap between the panel and floor and at the top of the panel is necessary to provide proper air flow.
Asbestos millboard is different from asbestos cement board or asbestos transite board. Asbestos millboard is heat resistant while the others are not.
WARNING: Inhaling asbestos fibers may be harmful. The effect of long term exposure is not completely known. However, you should wear a protective mask when cutting asbestos products.
Since brick and stone are good conductors of heat, they offer little protection if placed against a combustible wall or have wood studs behind them. To be effective, bricks must be placed out at least 1-inch from the wall with air gaps at the top and bottom. You can create the air gaps by using half bricks on the top and bottom row. Stoves can be placed as close as 12 inches from the brick facing if you provide an air space behind the brick.
An inexpensive and temporary way to protect a wall (if you already have a stove installed closer than 36 inches to an unprotected wall) is to provide a baffle. This baffle could be sheet metal, hardware cloth or cement board hung on metal brackets approximately 4 inches behind the stove.
Floor Protection Clearances
All floors on which stoves are installed, except concrete, must be protected from both heat of the fire and hot coals falling out when fuel is added. Metal with asbestos backing and asbestos millboard are non-combustible materials used for floor protection.
Fireproof clay tile, slate, brick, colored pebbles and marble chips can be used alone only if they are mortared in place with no gaps. If they are not mortared, or have gaps, then metal or asbestos millboard must be installed between them and a wood floor. A 2-inch layer of ashes or sand or bricks laid in the bottom of the stove helps to insulate the bottom of the stove and protect the floor.
In general, 18 inches is enough clearance to protect the floor if it is covered by non-flammable material, such as a sheet of 24 gauge metal or brick or fireproof clay tile. If the stove legs are from 6 to 18 inches long, 24 gauge sheet metal laid over a 1/4-inch sheet of asbestos millboard is needed. Legs of 6 inches or less require 2 to 4 inches of hollow masonry laid to provide air circulation and covered by 24 gauge sheet metal. If the stove has no legs, provide a sturdy support to allow air circulation under the stove.
The floor protection should extend at least 12 inches beyond the sides and rear of the stove, and at least 18 inches beyond the stove front, to protect against falling embers and for loading wood or removing ashes.
Before installing heavy protection materials such as brick, check the floor to make sure it can handle the increased weight. You may want to reinforce the joists under the floor. Consult a carpenter if necessary.
This information comes from Michigan State University Extension
