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attic insulation

Post in 'DIY and General non-hearth advice' started by cdodge04, Oct 15, 2009.

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  1. cdodge04

    cdodge04 Member

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    Hey guys,
    My buddy had ice dams every day last winter, and I kept telling him it was because his attic isn't insulated properly...too much heat is getting out in the attic causing everything to melt and refreeze.

    I attached a picture of what the insulation looks like in the attic right now. There is no insulation about a foot away from the roof in the attic...which is right where the dams were occuring. His attic does not have vents along the overhang...you cannot stand in the attic and look to the outside. I'm trying to tell him to put insulation up to the where the roof decking starts but not to have it touch the roof decking or he will risk having ice dams because of that...

    What do you guys say?


    EDIT: The red in the picture is where the insulation is...horrible drawing, but it gets the point across I think lol..

    Attached Files:

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  2. billb3

    billb3 Minister of Fire

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    are you sure the gap you are seeing is over the ceiling and not over the eaves ?
    [​IMG]
    there shouldn't be insulation in that red area (if pic loads) and there should be some sort of through the soffit venting there (although my house has the insulation in the eaves, and no air vents)
  3. cdodge04

    cdodge04 Member

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    Pretty sure it's in the attic...the house was built with no air vents in the eaves as well...I'll give him a call and check it this afternoon or tonight..
  4. d.n.f.

    d.n.f. New Member

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    You need air in there. Get some soffit vents and then get those channel things to keep the air uncovered on the attic side. With the airflow protected on the attic side you could then blow in insulation overtop existing.
  5. DAKSY

    DAKSY Patriot Guard Rider Staff Member

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  6. LLigetfa

    LLigetfa Minister of Fire

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    Ja, both are important, the soffit vents and the chutes.

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  7. coolidge

    coolidge Member

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    You will need the soffit vents ,plus some proper vents to get the require air flow. Make shure any insulation is placed over the top plate. The proper vents will stop the insulation from contacting the roof. Dont blow cellulose over fiberglass, it should go in first, it gets in the nooks and crannies better. If you do use the fiberglass over the cellulose make shure you rip the paper of the batts.
  8. Hogwildz

    Hogwildz Minister of Fire

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    The soffit vents will be useless unless he also installs a ridge vent.
  9. peakbagger

    peakbagger Minister of Fire

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    Most houses have entirely inadequate vents up near the ridge. A lot of builders go cheap and install some puny gable end vents as properly sized gable end vents require some framing and occasionally can let snow into the attic where it eventually melts and makes a stain on the ceiling below. Ridge vents work real well until a heavy snow fall where the ridge vent gets covered with snow so the ridge vents gets blocked. In that situation, if there is a sunny day after the storm, a lot of water can get generated and there is a chance of ice damming even it there are proper ventilation at the soffits, as there is no cold air flow up through the vents and the heat leaking from the house will slightly raise the roof temp, except at the soffits causing a dam. . Knowing the potential for "interesting" weather in the Belfast area, I would suggest a "belt and suspenders approach and use both a ridge vent and gable end vents in combination with, "proper vents" at the wall to roof intersection. Worse case is get some heat tape for the bad areas and turn it on whenever the conditions are right (generally a sunny day after a snow fall. There is no need to leave the tape on all the time.

    Some folks install a cupola vented to the roof as an alternative to a gable end vent but they to can allow snow into the attic during unusual snow conditions (generally high winds and snow will do it). BTW the solution for this for the cupola and gable end vents is to install a plastic lined tray under the opening so that if snow does get in there, it falls in the tray and stis there until it evaporates instead of melting down through the insulation.
  10. dave11

    dave11 Minister of Fire

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    I agree with all that's been said, but at the same time, i'm not sure the lack of soffit vents is the main cause of the problem. Lots of older homes, including mine, have neither soffit nor ridge vents, but never get ice dams.

    Too much heat getting into the attic is likely the problem, but before adding insulation, he should look high and low for air leaks of heated air into the attic. Sealing those is faster and cheaper, and might solve the problem. Extra insulation and soffit vents could be done later if needed.
  11. cdodge04

    cdodge04 Member

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    Hey guys,
    The house was built with no soffit vents...I attached pictures taken from the outside. There is a ridge vent and there is a vent on the front side of the house...

    Attached Files:

  12. NEDLAX

    NEDLAX New Member

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    Couldnt put it any better always airseal first. Also when puting in baffles roll some fiberglass and stuff under the baffle down to the plate, so the air has to go up the baffle. This prevents wind wash in your insulation (it degrades your r value at the eaves) in new construction i now sprayfoam from the baffle over the insulation blocking the wind down to the plate. this makes sure the air goes up the baflle and gives more r value at the eave. When all done in attic consider caulking the attic hatch shut you can always remove it to get in the attic. Sometimes people also forget to insulate above the hatch ;-) Every house i test its the worst spot on the atttic plane.

    Next i would look at your exhaust fans, do they just lay in your attic? where are they ran. where are they going,
  13. LLigetfa

    LLigetfa Minister of Fire

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    You could drill round holes between the rafter tails and insert round vents. The gable end vent needs to be larger than the combined area of intake vents.
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