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  1. #1
    Join Date
    Jan 2011
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    Default 1921 Church/vaulted roof

    Need to know the best way to Insulate the ceiling/roof, the framing is 2+8 actual, the church was built in 1921 and has a beautifully built box beam decoration on the ceiling , they had put a drop ceiling in at some point and have layers of standard bat insulation on top of that ,i want to remover the drop ceiling and move the insulation directly to the main roof do i need to use spray foam? or can i use the old bat type, there are no ridge vents .
    Last edited by bellows1163; 01-07-2011 at 03:50 PM. Reason: typing error

  2. #2
    Join Date
    May 2008
    Location
    Pacific Northwet
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    1,418

    Default Re: 1921 Church/vaulted roof

    If you are planning to reroof, you can place rigid foam insulation on top of the existing framing or skip sheathing, cover it with plywood, then place your roofing material on top of that.

    That's how it was done on my parents' house many years ago. The framing did not allow for insulation; there was no ceiling cavity. I don't know that it's the BEST way to do it, and there may be good reasons not to do it that way, but it might be a possibility to consider.
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

  3. #3
    Join Date
    Jan 2011
    Posts
    2

    Default Re: 1921 Church/vaulted roof

    the roof is fine and were not going to reroof we have 2+8 framing and the room for insulation, it,s what type is the question

  4. #4
    Join Date
    May 2008
    Location
    Pacific Northwet
    Posts
    1,418

    Default Re: 1921 Church/vaulted roof

    Assuming you are opening up the 2x8 cavities:

    Using fiberglass insulation batts will require providing adequate ventilation. Since this is a vaulted ceiling, you will probably need continuous soffit vents and a continuous ridge vent to provide ventilation to each ceiling cavity. You'll also need to make sure there is an air gap between the insulation and the roof, so that there is a continuous path for airflow between the soffit and the ridge. You can't completely fill the cavity with insulation. If you fail to provide this airflow, moisture that enters the cavity from the living space will condense on the underside of the roof and saturate the insulation and promote mold growth.

    Closed-cell spray-foam insulation can be applied directly to the underside of the roof. Because it is sealed to the roof, there's no place for moisture to condense so you probably won't need soffit or ridge vents, and you won't need to provide a continuous air space between the soffit and vent. Spray foam also typically provides a better R-value per inch than fiberglass.

    The cost of spray-foam may be higher, but you may decide that the benefits are worth it.
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

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