Question about sealing around fireplace
I posted something similar over in the General Discussion forum but didn't get any replies so thought I'd try here. Hope I'm not breaking any rules or annoying anyone with reposts.
I've got a fireplace with a stone surround (picture #1). The stone is not attached or sealed to the drywall at the edges of the fireplace (picture #2). This creates two problems:
A) The first problem is a combination of the wall gap and another gap in the fireplace itself. The fireplace has a gap between the "roof" and the angle iron at the opening that allows smoke to flow up behind the stone surrounding the fireplace (picture #3); and
B) Cold air can come in from behind the stone through the gap between the stone and the wall.
I'd like to seal the gap in picture #2 with something. Right now I have some fiberglass insulation pushed in there, but I'd like to use something with minimal expansion like Dap Window and Door foam sealant. Would this work? Are there any codes that I'd break by doing this?
I'm at a loss about the gap in picture #3. Something tells me it shouldn't be there but I'm not sure what to do about it. Any thoughts?