On 15 Nov 2005 11:43:05 -0800, "tmo" wrote:

This past weekend I was up in the attic getting ready to lay down some
insulation when I noticed that there was a pretty big gap between the
chimney and the adjoining wall running pretty much the whole lenght of
the chimney. I wasn't able to get close enough to measure it, but I'd
say it's close to an inch pretty much the whole way.

Is this something I can seal with a can of the spray foam sealant or do
I need something else?

That's supposed to be there. It keeps the chimney away things that
burn, so that your chimney fire doesn't cook off the rest of the
house. I don't think you should seal it at all, but if you do,
use something that's both non-flamable, and which doesn't conduct
heat well.