Question on Stove Pipe Installed in a Chimney Chase

[Greg in Alaska]

Hi All,
Thanks to the recommendations I received on this site, I am in the process of installing a Valcourt Frontenac fireplace. I have a question for you experts about the installation. I am installing it in a partially insulated chimney chase. The insulated portion goes up for 12', where the chase is then uninsulated for a total height of 28'. At the 12' level I have an insulated lid in the chase with a fire stop and attic radiation shield installed as per manufacturors recommendations to keep the insulation away from the stove pipe. The installation has all been 100% in accordance with the installation book. The issue I have with the installation is there is a ~1/4" gap all around the chimney at the fire stop. This doesn't seem to make much sense to me. If you have an insulated chase, but allow a 1/4" gap around the stove pipe, the cold air in winter is just going to travel down the gap and fill the entire chase with cold air when the fireplace is not in use. What good is the insulated space with this gap. Might as well not have any insulation in the chase at all. My question is, would it be permissable to use a high temperature silcon caulk, and caulk this joint to stop the infiltration of cold air. In Alaska in the winter time, this could be alot of cold air coming into the house. Thanks for your reply's. Cheers,
Greg

 

[begreen]

Yes, I'd use some good quality silicone to seal the gap.

And welcome Greg. You live in some beautiful country up there.

 

[skinanbones]

silicone is fine but allot of chimney manufacters recomend a storm collar on the top of the attic radiation sheild as well. I know on the ICC Excel once thats in place there is no air leakage back into the room

 

[r_towle]

Fire stop caulking.
Expands if it start burning.