Expert: Steve Tavares - 12/1/2009

Question
Hi Steve, wondering about putting a non-combustible insulation (roxsol) in the space around the horizontal chimney.  Don't like the idea of leaving that space.  A friend had his chimney done by a pro who left it uninsulated and he had major condensation on the inside of the chase.  It's a 3 1/2 " gap, and I can't see it having adverse effects on the chimney which is a two in one.  The dealer said it shouldn't hit more that 150 degrees, and it is near the end so it should be the coldest point in the chimney run.  I would really like to put something in to prevent the cold and condensation.  Any suggestions greatly appreciated.  Kent Gray....

Answer
I still wouldn't suggest putting any sort of insulation touching the chimney. The manufacturer suggests a certain clearance and I would suggest keeping that said clearance. One thing that should have been done is the chase that the fireplace sits in should be insulated and vapor barriered and sheeted.

This will help with some of that condensation issues.

Hope this helped.