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Old 07-17-2012, 10:01 PM   #1
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Insulation Around Chimney

Hi All,

My wife and I recently purchased our first home- I was the lucky one assigned to the summer attic projects.

Basically, I'm just going through and improving upon the existing insulation, but one of the challenges I've come up against is insulation around the chimney.

I've read that a clear space of 2" should be maintained around the chimney. The current setup is a 4 flue interior masonry chimney. The second floor is divided so that one half (master bedroom) has a cathedral ceiling while the other half an 8' ceiling with attic overhead.

It appears that when the master bedroom was framed, fiberglass insulation was placed between the drywall for the master bedroom and the chimney. There is a lined stove hookup directly below it in the bedroom. I can see the insulation from the attic, but the insulation is between studs and chimney, so there is really no means to access it without tearing down the wall.

Just curious if anybody has had any experience with fiberglass insulation against a masonry chimney, and whether the concern is significant enough to consider taking the wall down and removing.

Apologies if I don't make much sense! If that's the case, I'll post some pictures to help clarify.

Thank you all for your time.


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Old 07-18-2012, 11:00 AM   #2
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Insulation Around Chimney

I have never seen FG combust but you need to check with the code in your area and if it can be run zero clearance in that case.

Roxul is a better choice as it will never combust and even better would be to seal that area off with some sheet metal and itumescent sealant.

Build the metal up to a level that when you blow in the new insulation, it will not come over the top and touch the chimney.

Sealing that are against air leaks is better for safety and energy efficiency.


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Old 07-19-2012, 01:44 PM   #3
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Insulation Around Chimney

You are correct, Code R1003.18 Chimney clearances says that you must maintain a 2" clearance from combustibles. They do give you an option of lining your chimney flue with a stainless steel liner and insulating that liner to meet UL1777 standards (1/2" of insulation around the liner), then you would have zero clearance, that would allow combustibles to be placed next to the chimney.
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