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cracks around fireplace


greylander's Avatar
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02-12-10, 02:28 PM   #1  
cracks around fireplace

My new home has a fairly typical looking fireplace. The actual fireplace is metal, surrounded by brick mantle and presumably brick chimney. The fireplace has glass doors, vents at top/bottom for a blower.

Today I noticed a great deal of cold air coming in, not through the damper, but through gaps/cracks between the brick of the mantle/chimney and the metal of the fireplace.

I am thinking that I need to maybe spray in some kind of foam gap filler, or insulation or some such, and/or patch of the gaps with fresh mortar. Obviously whatever I use to insulate and/or seal the gaps has to be something that will not melt or burn as it would be in direct contact with the metal housing of the fireplace proper.

Also, any good links to information on firplace construction in general, so I can start to understand what is going on inside the wall/chimney, would be helpful. For example, I can see throught he top vent to where there is a metal duct going up into the chimney. Presumably this goes all the way up -- round pipe inside square chimney. So is cold air coming down bewteen pipe & brick of chimney and out through the gaps? For that matter, is the outer "shell" of the fireplace/chimney brick all the way round and up (I am guessing this would be normal, but I don't know -- outside is covered with siding, so can not seen chimney construction). Help just with terminology would also be appreciated -- what is the metal part called? (I've seen the term "insert", but that seems to be more specific to stove-like replacement for normal fireplace).

OK, that's enough rambling. Any help/advice will be most appreciated.

 
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xvimbi's Avatar
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02-12-10, 07:09 PM   #2  
A possible solution

I've got draft issues with our fireplace as well. In my case, air is coming in through gaps between the fireplace box and the mantle as well as through the grilles at the top and mostly at the bottom. Likely what is going on in your case (as well as mine) is that the builder did not insulate the 'doghouse', i.e. the space around the fireplace and/or the floor below is not insulated (well), so that you get cold air coming up into the wall and out of the fireplace opening. If you happen to have power outlets next to the fireplace, check for cold air coming out there as well. That would corroborate the notion that the wall is not (well) sealed.

Funny thing is that I just, literally, finished sealing our fireplace two minutes ago. I simply cut a piece of 1" rigid foamboard to fit in the mantle opening, put weatherstripping around the edges and jammed it in there. No more draft, but it looks, um, funkay (pink). It's only a temporary fix. I might put some wood over it or paint it to look even more funkay. As you can tell, we are not really using our fireplace.

In any case, the gaps need to be sealed. If they are wider than about 1/4" you could stuff backer rods (also called caulk saver) in there and then caulk. There is special caulk that is used around the fireplace box. Home centers should have it; better yet get some from the guys who installed your fireplace. Having said that, if the house is not that old yet, contact the builder and yell at him.

Good luck! MM

 
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02-14-10, 04:07 PM   #3  
I have the same problem. Moved into this house in the Summer and discovered that there is very cold air escaping through every conceivable gap on the fireplace. I initially placed insulating foam but found it did not cure all the gaps. I the placed (dont laugh - noob) a towel between the glass doors and the interior 'grate' of the fireplace. Its much better now but there are still gaps where the brick work meet the metal fireplace and where the towel doesn't reach. I want a more permanent non-noob fix for this....fyi my damper is at the top of the chimney.

I might try the insulation foam board xvimbi suggested

 
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02-15-10, 01:19 AM   #4  
Chimney balloon?

Can't picture your exact situation, but would a chimney balloon help?
I discovered those recently: Inflatable Chimney Balloon Stops Drafts (and Santa)

 
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02-15-10, 06:06 AM   #5  
Posted By: Jammos I the placed (dont laugh - noob) a towel between the glass doors and the interior 'grate' of the fireplace.

I might try the insulation foam board xvimbi suggested
I won't laugh; initially we put some foam strips between the grille openings. That didn't look too hot either. I played with the idea of putting a piece of heavy glass or acrylic over the fireplace, but that would cost about $200. So we wanted to see if covering the fireplace made a difference in the first place, and it did. A nicely designed wooden covering sounds good too, but it won't have quite as much of an insulating effect. Undecided still.

But as LucHt is alluding to, stopping the air flow a bit closer to the source might be a better idea. But you got to find out where the air is coming in first.

MM

 
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02-15-10, 01:21 PM   #6  
Posted By: LucHt Can't picture your exact situation, but would a chimney balloon help?
I discovered those recently: Inflatable Chimney Balloon Stops Drafts (and Santa)
Thanks - I think have to try this....

Amazon.com: Fireplace Chimney Draft Stop Plug Balloon (Large Pillow) - Fits Any Masonry Fireplace.: Kitchen & Dining

 
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