Ideas on sealing space around chimney


  #1  
Old 11-16-14, 06:55 PM
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Ideas on sealing space around chimney

Hi, I am working on my attic and starting with a couple of the larger air leaks first before getting into the rest of it. This is an older house, 2 story with basement. I am wondering what to do around my chimney since it is at the edge of the roof and hard to work around very well. This chimney has a 6" stainless liner in it and is used for an oil furnace. It looks like the sides of the chimney are somewhat blocked off with wood or drywall, the front of the chimney has and open space that has fiberglass in it, and the back side I don't know what is there because you can't really see it. I know there is a good air leak here because the frost or snow on the roof will melt on along that rafter section from the chimney up to the peak of the roof. That is one reason I am looking here first.

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  #2  
Old 11-17-14, 11:44 AM
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Chimneys aren't my specialty, I deal with flashing them to block air leakage from basement to attic. But yours appears to have some serious problems.

I assume that was an earlier fire that you are aware of?? If not a fire, then maybe discoloration from moist air from the basement?

There looks to have been water leaking in from the roof evidenced by the white streaking on the bricks.

There is supposed to be a 2" space between the brick and any combustibles. Is your chimney tile lined or have a metal insert? If just a brick chimney then there is little protecting the wood next to it.

What is venting through that chimney?

Others will be along.

Bud
 
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Old 11-17-14, 04:03 PM
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Thanks for the reply, I understand that by todays construction it is not right, but I have to work around what is already there. Yes there was a fire way back and can be seen on some of the wood. If you notice in the pics that the framing on the floor part of the attic is newer looking than the roof.
I do have the space between the chimney and framing in the basement sealed off, and I am guessing that any air leakage is somewhere as the chimney goes up through the house. I would also say without being able to see it, but there may be an open area where the chimney passes between the 1st and 2nd floor.
 
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Old 11-17-14, 05:20 PM
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Wall cavities and joist cavities are all connected through the leaks between the drywall and the wood framing. As one person explained it, turn your house upside down and try to fill it with water. It would pour out everywhere.

The primary path where the chimney passes through floors or ceilings is usually sealed with sheet metal and sealed to the brick with fire rated caulk. I'll add a link on air sealing from our friends in Vermont.
http://www.efficiencyvermont.com/ste...ide_062507.pdf

Bud
 
  #5  
Old 11-17-14, 06:14 PM
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Thanks for the info. Does it look like there would be any way to do a good job putting the sheet metal in place around the chimney. Given the space to work in and the existing situation, I can only come up with maybe putting a sheet metal on the front side with the ends bent down to close off the space, and then culking along the side to what is there already there. If there is any space on the backside then nothing could probably be done about it. Another thought if I ever replace the roof that would be a good time to fix up around this chimney better. (it does have good flashing around it now so no leaks)
 
 

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