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  1. #1
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    Default Insulation suggestions

    We live in a split-level home built in 1964. It has cathedral ceilings in the LR/dining area. The roof is gently sloped and it appears there is only about a foot or so space between the ceiling(s) and the roof. Is it possible to insulate this space. I have had a couple of contractor in and they suggested it would be more trouble than it's worth..that is the R-value wouldn't be increased enough to cover the cost of the work even over 10 years.

    We have already replaced all windows/doors. Our heating/cooling costs are reasonable (we're in Quebec, the power generating capitol of Canada ) so I am now wondering whether it's even worth the trouble.
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  2. #2
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    Default Re: Insulation suggestions

    If your contractors estimate a break even point after 10 years, AND if you plan on living in the house for more than 10 years - you know the answer.

    One thing for sure here: heating rate/cost will go up.

  3. #3
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    Default Re: Insulation suggestions

    Well the 10 year estimate was their GUESS. They all were pretty vague about how they would do it and whether it was worth it. It seems to me the best way would be to replace the roof which needs replacing and while it's open either spray foam and batt insulate it..then cover it all up. I just don't know how much heat we're losing through the roof. 5 years ago we're placed our oil furnace with an electrical furnace/heat pump combo, and replaced all the windows and doors. Our heating costs fell by 75% and now our total energy bill is about $2000 year. How much lower can we go ? We do place to live here for another 10 to 15 years.
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  4. #4
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    Default Re: Insulation suggestions

    Considering the age of your home and the description, gently sloping cathedral ceilings, I would question its construction. I have seen houses of that era that used a large ridge beam, 6x12 or so with rafters placed on top of the ridge beam instead of attached to it. Sometimes the rafters were larger 3x8 or 3x10 and placed on longer centers, 32" or 48". The decking for the roof were insulated panels usually made with some type of cellulose insulation sandwiched between a top layer of plywood and a bottom layer of fiberboard.

    These panels would only be about 2 to 3" thick so the R-value was not all that great, R-7 or so, but it was continuous, no breaks and the roof was then covered in tap and white rock. The beams were often left open to the room below.

    Yours may have been of a more traditional construction, but I would have to wonder if the roof decking is not made of these panels. If it is, then the added insulation in the cavities may not have as quick a payback as you might hope. Also if you have these panels, insulating between the cavities may not be the best approach. You best approach might be to add 4 to 6" of rigid foam board above the existing roof and then a membrane cover over that.

  5. #5
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    Thumbs up Re: Insulation suggestions

    Quote Originally Posted by keith3267 View Post
    Considering the age of your home and the description, gently sloping cathedral ceilings, I would question its construction. I have seen houses of that era that used a large ridge beam, 6x12 or so with rafters placed on top of the ridge beam instead of attached to it. Sometimes the rafters were larger 3x8 or 3x10 and placed on longer centers, 32" or 48".
    That sounds like the way this house was built - there is a large steel beam which runs back to front separating the LR/dining room area. The beam is visible below the ceiling so I suspect the rafters are on top of it.

    The decking for the roof were insulated panels usually made with some type of cellulose insulation sandwiched between a top layer of plywood and a bottom layer of fiberboard.

    These panels would only be about 2 to 3" thick so the R-value was not all that great, R-7 or so, but it was continuous, no breaks and the roof was then covered in tap and white rock. The beams were often left open to the room below.
    Not in our case. The top of the roof is tar/gravel..and needs replacing.
    Yours may have been of a more traditional construction, but I would have to wonder if the roof decking is not made of these panels. If it is, then the added insulation in the cavities may not have as quick a payback as you might hope. Also if you have these panels, insulating between the cavities may not be the best approach. You best approach might be to add 4 to 6" of rigid foam board above the existing roof and then a membrane cover over that.
    That sounds like the best plan of attack - the roof needs replacing anyway so that would be the best time to do it (obviously).

    Thanks for the detailed reply -
    ---I belong to too many forums---

  6. #6
    Join Date
    Dec 2007
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    Default Re: Insulation suggestions

    That was supposed to be tar and white rock not tap and white rock. The white rock is a white gravel, usually pea sized.

  7. #7
    Join Date
    May 2009
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    Smile Re: Insulation suggestions

    Yeah that's what I thought it was


    Thanks
    ---I belong to too many forums---

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