Chimney clearances

[Geoff]

I've been searching around and I can't find the answer, so its time to ask:

What clearances to combustables is required for a masonry chimney lined with clay flue tile? My chimney is lined with flue tile and I think it is constructed of masonry blocks (although most of what is visable is surrounded by bricks for asthetics). It looks like I probably have a 1" air gap between the blocks and the flue tile (not sure on that). Is the measurement taken from the flue tile or the masonry blocks? What about if a layer of bricks is also surrounding the masonry blocks (with or without an air gap)? Is the clearance the same if a flexible stainless steel liner is put into the masonry liner?

Thanks in advance!

 

[Shane]

THis is from memory so if I'm wrong someone please correct me. An interior brick chimney should have 2" of clearance to combustible framing members. An exterior chimney should have 1". Between the flue tile and brick should be a min of 1" airspace. I think that there is also a maximum of 4"-6" space between flue tile and brick as well. With a properly insulated stainless liner I believe you can have "0" clearance to the combustible framing members of the home.