interior chimney block off plate with just insulation or with sheet metal also

Use both, the sheet metal really helps reflect the heat back into the house. I noticed a big difference when I installed mine.

I agree with weatherguy to a point. First, do you have an insert or a freestanding stove? I have a Jotul F600 freestanding stove that sits in front of my fireplace opening. My chimney is massive (8' x 4' x 15') located centrally in our home. I installed a block off plate with one layer of insulation lying on top of the plate, but not packed tight around the liner. This allows some heat to escape into the massive chimney that acts like a heat storage mass to release heat much longer back into the house. For example, the backside of the chimney makes up a large part of a kitchen wall and after a fire has been burning for several hours I get readings off the wall up in the 80s. So, if your chimney is exposed to release heat to other parts of the house where you want more heat then it might be better to just go with a block off plate to let a bit more heat escape into the chimney.

tumm21 said:

what type of metal should I use? Galvanized? Also what gauge should I use??

Click to expand...

I got a piece for $10 at Home Depot, not sure what it is but it was cheap enough.