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HankMaine 01-03-2013 03:31 PM

Wrap chimney in attic?
1 Attachment(s)
About 6 months ago we stripped our cedar siding, wrapped house in fanfold, installed new vinyl siding and replaced every window in our house. To say we have noticed a drastic change in noise, drafts and our general comfort would be an understatement. That's the good news, the bad news is that we have exposed another flaw in our home. We normally get ice dams, nothing major but it's Maine so a few icicles never worried me. This past week I notice 5-7' icicles hanging from my roof and a massive amount of ice damming. I put 2+2 together and theorized that all the heat which used to escape out my windows is now escaping through the ceiling and into the attic. When we did the siding I took a peek in the attic and discovered we only have 6" of fiberglass insulation (see attached). Now my plan is to install soffit baffles and blow in 12" of AttiCat but I'm thinking that only solves part of the issue.

We heat primarily with wood (stove in basement) and I noticed the chimney brick on the 1st floor gets quiet warm when the stove is going so I imagine the chimney in the attic get's warm as well. Even though I'm bumping up to about R42 on the attic floor I'll still have a heat source in the attic which will melt the snow and cause ice dams.

My plan is to wrap the chimney in unfaced batts and secure them by wrapping in foil tape. I've seen a few discussions on the topic and I'm just curious if anyone else has done this. Would this be the best method? Am I going overboard and wasting my time? Perhaps the little bit of heat displaced by the chimney is not enough to worry about?

Any thoughts or advice would be appreciated.

Windows on Wash 01-03-2013 11:54 PM

Seal the connection between the attic floor and the brick and mortar with sheet metal or fireproof drywall. Code would dictate that the insulation (loose fill) be removed from direct contact with the chimney and isolated. That will do a bunch to stop the warm air transmission (as well as sealing top plates and other penetrations into the attic) which is usually the more sizable culprit when it comes to ice dams.

If you wanted to insulate the chimney (not sure how much good that would do), I would stick to the well established compatible insulation with heat. Roxul and other stone wool insulation are completely non-combustible and would be much more stable in this case as compared to even fiberglass.

HankMaine 01-04-2013 11:21 AM

Took your advice and headed to my local home improvement store at lunch. I was originally going to get some aluminum flashing type of material but I discovered Reflectix. Reading the package in the store it said 'two reflective layers of aluminum with air pockets between' but I just checked their site and now I see the 'air pockets' are actually polyethylene (bubble wrap) wrapped in aluminum. So I'm guessing this would not be a good product for the gap between the attic floor and brick? Product does say it's Class 1 Class A fire rated. Thoughts?

HankMaine 01-05-2013 07:28 PM

I'll be going with sheet metal, did a little test today and discovered Reflectix burns easier than cardboard.

joecaption 01-05-2013 08:09 PM

More important to make sure the roof is vented properly.

AllanJ 01-06-2013 07:07 AM

From the picture I noticed that your roof pitch is quite steep. After just a day or two, does the snow fall off so the upper part of the roof is bare long before the parts along the eaves?

Sun on the bare part of the roof would heat up the attic interior.

Windows on Wash 01-06-2013 10:55 AM


Originally Posted by HankMaine (Post 1087120)
I'll be going with sheet metal, did a little test today and discovered Reflectix burns easier than cardboard.


Its glorified plastic. Don't put that stuff anywhere near heat.

HankMaine 01-07-2013 03:10 PM

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WOW - Hard to believe they promote it as Class 1/A but there are all kinds of suckers like me who don't know any better :huh: That class must mean 'burns well'.

Joe- I have gable end vents and I'll be putting soffit baffles in to ensure good circulation continues.

Allan - I do not really have any bare spots aside from where I rake it.

After spending part of the weekend up there I discovered some places where insulation was mashed down to about 2" thick, other places where it was pulled back over a foot from the eve and other spots where electrical wires popped insinuation up in the air. No wonder the mice loved it up there, nice and warm. I also discovered my father's handy work (God rest his soul) .. and it was not exactly 'code'. I've opened Pandora's box so it will be a while before I even get to the insulating :censored:

Found a 2nd floor bathroom fan with no duct work or vent, just blew air into the insulation over bathroom :eek: Then when inspecting the chimney I noticed daylight around the flashing. Oh.. and the icing on the cake (see attached). Going to be a long couple weeks :wallbash:

The good news.. when I'm done we will be warmer and safer!

HankMaine 01-07-2013 03:13 PM

Almost forgot, back to my original question. I had a roaring fire going and the chimney in the attic was cool to the touch. Now I know, it wasn't the chimney 'heating' the attic.

Windows on Wash 01-07-2013 04:30 PM

Good job searching around.

Get it all buttoned up and you will be that much warmer and safer as you said.

Missouri Bound 01-07-2013 09:37 PM


Originally Posted by joecaption (Post 1087151)
More important to make sure the roof is vented properly.

This is what you need to be concerned about first. Properly insulated and ventilated attic spaces won't have the conditions necessary to create ice dams. Do you have soffit vents and are they unblocked with insulation or covered up? And I hope you got that electric straightened out as well

Windows on Wash 01-08-2013 08:13 AM

If a house leaks enough air, even a vented attic will ice dam but yes, the venting should be checked and verified for correctness.

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