Is this gap in my firebox normal? (Between bricks and damper casing)

Old 01-30-18, 01:19 PM
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Is this gap in my firebox normal? (Between bricks and damper casing)

Hi all,

I'm repairing my firebox (Novice DIY) and noticed that there's a gap between the damper casing and bricks just above the lintel. Is this normal? There's some insulation in the gap as well but no refractory cement.

I was reading an older article that said it was to allow for expansion when the casing gets hot. I have not seen anything else to confirm that, however.

Any ideas? Should I fill the gap with some refractory cement or leave it alone?

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Old 01-30-18, 05:23 PM
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I am not the pro here but something doesn't look right.
You have a space of 1/4"-1/2" where you can see regular house insulation ?

Originally I was thinking the insulation is not a fire stop but since it's contained within the brick firebox... it doesn't need to be. I would also think there would be a lot of air leakage thru the insulation.

If no one addresses this I'd want to get a chimney mason or chimney sweep in to check it out.

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