National Fire Protection Wood Stove Installation

Wall Clearance

• The stove must be placed at a space far enough from the wall surface behind the back of the stove to prevent fires. If you place the stove in front of an unprotected wall, which would be one without a heat shield made of 28-gage sheet metal or asbestos millboard, the NFPA sets a minimum wall clearance of 36 inches. NFPA wall clearance guidelines are less if you incorporate 1 inch of air space between a back wall and then attach install a heat shield wall made with millboard and sheet metal. For example, if you have a circulating stove that has a lined combustion chamber, and attach sheet metal on top of asbestos millboard, the recommended wall clearance can be as low as 4 inches and 12 inches for a radiant heat stove.

Floor Protection

• The NFPA recommends that you install a 24-gage sheet metal floor or higher, or use sheet metal with an asbestos millboard underlay. If you want to cover the material with brick or slate, mortar the material into place, with no gaps, to prevent heat from transferring through the crevices. No overlay materials are required if you build a concrete floor or hearth. The floor area directly underneath the stove must extend 12 inches beyond the sides of the stove, and 18 inches beyond the front of the stove and any side of the stove that has a door. If the stove legs have less than 6 inches of clearance from the top of the leg to the floor, install 2 to 4 inches of hollow masonry to improve air circulation for the heat generated from the bottom of the stove. It is also advisable to add a 2-inch layer of sand or ashes under the bottom of the stove to prevent it from overheating the hearth area.

Stovepipe

• Keep stovepipes as straight and short as possible, and allow an 18-inch clearance from an unprotected wall or ceiling. If the wall is protected (using asbestos millboard and/or 28-gage sheet metal) the clearance can be as low as 12 inches (with asbestos millboard, only), and 9 inches if you attach sheet metal to the asbestos millboard. The NFPA does not permit a stove to pass through any floor or ceiling unless combustible materials are removed within 18 inches of a non-insulated stovepipe. If you wish to close off the opening, use a fireproof material such as a metal or burned fire-clay thimble around the stovepipe. Discuss appropriate fittings, accessories and confirm specific requirements for your area with your stove retailer, installer and local building code agency.

Chimney

• Install the stove as close as possible to an existing masonry chimney, or use use a new prefabricated metal chimney or have a new masonry chimney custom-built. The stovepipe connection to the chimney should not exceed 8 to 10 feet. Limit elbows for stovepipe-to-chimney connections to no more than two and only use 90-degree configurations.