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  1. #11
    Join Date
    Apr 2008
    Posts
    26

    Default Re: Insulating void space, flat roof with balloon structure

    It has the mansard on the front and side. The parting wall is what I believe is called a pa****t wall. The back is flat. no eaves or overhangs. There is a facia that goes the back side and front which amounts to a 2 x 10 or so with aluminum for looks. The roof slopes back to front no ridge. Their are vent stacks for drain waste. One that runs up the parting wall along with the gas furnace chimney and another along the rear wall where the previous owners installed a half bath in the basement and ran a designated vent. I have two attic vents. If you can divid the roof area in thirds, I have a basic vent in the rear third of the roof, say left of center if looking at the front to the rear, and the other is an aluminum finned vent that spins to vent out, located in the front third also to the left of center. The reason it off the center line is their is a skylight installed in the bathroom for ventilation and they wanted to space things out.
    The vents in the wall are in the brick wall itself. Their is no eves or overhangs to vent. The Mansard basically is vertical in the back and sits back off the wall about 16 -18" and is about 3' high, pitches down and out as a traditional pitched roof does and runs just proud of the facia on the walls for run off.

  2. #12
    Join Date
    Dec 2007
    Location
    Tennessee
    Posts
    1,744

    Default Re: Insulating void space, flat roof with balloon structure

    OK, I think I am getting the picture now. When you had this TPO cover put on your roof, did they put any rigid foam boards under it? It is not uncommon to put anywhere from 3/4" up to 6" thick foam panels on top of the old roof deck and then cover it with the material. If that was done, especially if 3 to 6" thick panels were used, I would not bother with anymore in the attic. The payback just won't be there.

    You can insulate up above the ceiling joists, but not to the rafters. Where possible, you want 2" or more of space for airflow under the rafters. The problem is you have very little room with which to work. I can see why a contractor wants to charge so much.

    If it were mine, I would pull down the ceiling sheetrock and insulate with 6 or 8" faced fiberglass batts, then put up new sheetrock. That will be messier, but it is the only way that I can see of getting a nice even layer of insulation in the ceiling and guarantee that there are no voids that lead to heat loss and no build ups that would block the attic ventilation. It would be done right and it will last.

    BTW, if you choose this route, staple the flanges of the batt face to the bottom of the joist, not to the sides as a lot of contractors do. It will work better this way.

  3. #13
    Join Date
    Apr 2008
    Posts
    26

    Default Re: Insulating void space, flat roof with balloon structure

    Got it thanks. Thank is actually the long term plan... I hope. Yes it is messy I agree but I have plaster and lathe I would love to and plan to remove and sheet rock. But for now there is an area in would like to address and will take your advise with the amount of blown in as a long term temporary but correct solution.
    Thank you for all of your time with this. Hopefully their are others that can follow this thread and solve an issue like mine. Thank you again for a clear and time consuming answer!

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