A wood stove is a great way to heat a home, but if you don't protect the wall behind it, you can damage the wall. Heat shields can protect your wall and radiate heat back into a room. Shields should cover all areas around a wood stove (above, below, behind and on the sides).
If you are going to construct your own heat shield, you should make it from at least 28-gauge sheet metal, according to the National Ag Safety Database. Mount it 1 inch off of the wall on non-combustible spacers. You should also mount the shield off the floor so air can circulate freely between the shield and the wall. Cover any area within 36 inches of the stove with the heat shield. This type of heat shield will allow you to place the wood stove as close as 12 inches to the wall.
Without a heat shield, your unprotected wood stove should be at least 48 inches away from walls, according to the Wood Heat website. Heat shields can drastically reduce that clearance number. What makes a heat shield effective is the air space between the shield and the wall. The air space creates a convection air flow to keep most of the heat from reaching the wall.
Though sheet metal is a very common material used for heat shields, you may also use brick and ceramic tiles. Ceramic tiles and brick heat shields can reduce your clearance requirements by 50 per cent. If you combine them with a 29-gauge sheet metal back, you can cut the clearance by two-thirds. Your heat shields don't need to be made of the same materials. For instance, you can have a floor heat shield of brick and wall heat shields of sheet metal.
You can purchase a commercial heat shield that has been tested and certified as effective. Tested shields will have labels certifying they have been UL certified. Some types allow you to mount them directly to a wall without the need for spacers.
You can also use heat shields to allow stovepipes to be placed closer to a wall. Normally a stovepipe needs a clearance of three times its diameter, according to the National Ag Safety Database. For example, a 6-inch diameter stovepipe would need an 18-inch clearance. Using a sheet-metal heat shield as described above allows the clearance to be cut by two-thirds. Using the example, the 18-inch clearance would be cut to 6 inches.
If you have purchased a new wood stove, chances are you don't have to worry about a heat shield; it is probably built into the stove. This allows these newer stoves to be placed closer to unprotected walls than would normally be safe. With some models you can place the wood stove as close as 6 inches from a wall.