JP, in the case where the exterior wall of the house is flush with the chimney, the point where the chimney's sides meet would be the limit of the clearance applying--not the length of the whole wall.

I see wood furring strips on chimneys all the time and I see ungrouted CMUs all the time. Still wrong.

I tend to agree with Jerry M. esp. with regards to seismic country. After seeing Dale's photos and the Rampart General precast fireplace he has in his shop, I don't see how you could leave a full masonry Fp in a home after a seismic event. Those factory chimney conversions are very wishy-washy with regards to how to anchor them and, to my knowledge, no one has tested any anchoring system such as Tapcon screws to seismic requirements. The current building codes call for the bond beam to be tied into the building. This is to delay the collapse of the chimney sufficiently so the occupants can escape without being crushed. Something to think about. The problem with Calif. is, you can have Dale himself inspect a chimney and have a seismic event or mud slide damage the chimney before he gets to the office and writes up his report. Inspections are a snapshot in time.

Not only have I never seen a single code compliant chimney, I don't know anyone who has ever seen one that meets 100% of the code unless Dale is holding out on me.

Bob

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Keep the fire in the fireplace.