Question: I have read where it states you can use brick with an 1" air gap next to a combustible wall surface. I wanted to know if you did not use the 1" air gap on a combustible wall and without removing the wall to make it solid masonry only, how thick would the brick layer need to be on a combustible wall surface? It just seems that eventually enough layers of brick could be placed on a combustible wall surface??? Answer: According to NFPA 211, a single brick wall placed directly against a combustible wall will reduce clearances by 33% to the original wall. SOME building inspectors consider two layers of brick or 8" of masonry to be a "non-Combustible" wall, and therefore allow stoves to be an inch or two from this wall...but this is NOT detailed in NFPA..and I cannot assure you that it is safe. However, common sense would dictate that having MOST modern stoves a few inches from such a wall will be a safe installation.