Posted: 12/17/2012 6:01:23 PM EDT
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We don't need no stinking insulation.
I'm buying a new house. New to me, built in '41. It needs a new roof and we are going to have that done this summer. It also needs insulation, windows, siding, new furnace, plumbing, water heater, electrical panel and so on. So my question on insulation. I was considering having the underside of the roof spray foamed. Has anybody here had this done? Also looking at foam injection for the exterior walls. |
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Quoted:
We don't need no stinking insulation. I'm buying a new house. New to me, built in '41. It needs a new roof and we are going to have that done this summer. It also needs insulation, windows, siding, new furnace, plumbing, water heater, electrical panel and so on. So my question on insulation. I was considering having the underside of the roof spray foamed. Has anybody here had this done? Also looking at foam injection for the exterior walls. hell no on the foam roof spray. looking into air sealing your home! spray foam can be pricey so becareful shopping. |
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Quoted:
We don't need no stinking insulation. I'm buying a new house. New to me, built in '41. It needs a new roof and we are going to have that done this summer. It also needs insulation, windows, siding, new furnace, plumbing, water heater, electrical panel and so on. So my question on insulation. I was considering having the underside of the roof spray foamed. Has anybody here had this done? Also looking at foam injection for the exterior walls. Yeow, what doesn't need replacing? Want to buy in CT? I've got a nice fixer-uper for sale that doesn't need half that stuff. I've never heard of spray foaming the underside of a roof, generally the attic is supposed to be an unconditioned space and the insulation is at the floor of the attic. This keeps the underside of the roof cold in the winter helping to prevent ice dam issues, and it keeps the roof cooler in the summer by not trapping the accumulated solar heat in the roof deck. Foam in the walls is dandy for new construction with the walls open, I'm not sure I'd trust it to fill evenly with injection and I'd also be a bit concerned about pressurizing the wall cavity and popping drywall. Foam also means it will be nearly impossible to fish new wiring in the walls. If the house needs that much work, I'd consider ripping out the drywall, doing any electrical work, installing some PVC conduit in strategic locations to allow easy wire runs for TV, network, etc. and then insulating before putting up new drywall. |
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My close relatives have built three houses where the underside of the roof decking was insulated with spray foam.
My BIL's upstairs attic bedroom still warms up to the point that it is difficult to cool with his ac with outdoor temps in the 90s and all day summer sun. He needed to install a larger duct, but it's too late now. I think he had 8 inches of foam applied to the roof decking. The other two houses have some shade, different orientation, and don't have sleeping areas in attic trusses, so that isn't really an issue. Shingle temperatures stay about the same in unventilated systems as with ventilated systems. The big thing to watch out for is water vapor and condensation. You need to have enough foam to ensure that there isn't condensation. Open cell foam may not act as a vapor barrier depending on type and thickness, so plan for that. It may be MUCH cheaper to insulate with fiberglass or cellulose. |