Damper Removed

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Apr 19, 2009
South central MA
I had an wood burning stove-insert installed in the firebox of my living room fireplace. I have it installed without the faceplate usually surrounding the stove and closing off the firebox from the room. I like the effect. It looks more like a wood burning stove in the firebox then an insert as it provides the appearance of depth...

The problem is when they installed it they hacked out the existing damper above the firebox in order to snake the new liner up the existing chimney. This is akin to leaving the damper fully open all the time. The stove must heat up the entire length of air space in the chimney, and keep it warm, before the maximum benefit of the stove in the living room can be felt and when the stove is not in use there is a cool draft in the living room.

What can I use to block the opening to the chimney around the new stove pipe above the firebox in the open area of the former damper? Can I use regular fiberglass insulation with the backing removed or is there something else more heat proof?


Minister of Fire
Dec 12, 2015
Long Island, NY
Stuff Roxul (now called Rockwool) up there and block the opening with sheet metal or cement board.

Blockoff plate from the wiki (photos from member projects)

Fireplace insulation project

There are lots of threads to read. Search for "blockoff plate".

Don't ever use fiberglass around the flue. (I know, many pro installers do.) Fiberglass insulation melts at 1300°F, far cooler than a chimney fire It also degrades into chunky stuff at much lower temperatures.

Stone wool is not much more expensive and will not let you down long term.
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