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insulating cape cod

lagattutatf's Avatar
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01-03-02, 05:34 AM   #1  
insulating cape cod

problem : cape cod with r-19 pink fiberglass on attic floor ( i.e. ceiling of upper room). knee walls of upper room insulated with r-13 fiberglass. sloped ceiling of upper room (rake of roof) is uninsulated. no way to put insulation bats here, blown in insulation would have no vapor barrier and also block air flow. This room is losing lots of heat and is uncomfortable to live in. I have available to me 3 inch thick foam board with a tar paper like facing on both sides. I wanted to cut this to fit into the uninsulated space but have been told by "experts" that this would not be a good thing to do as water vapor would condense on the tar paper facing and cause damage.
Any solutions to insulating this space or any comment on using the foam board for insulation ?

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Join Date: Nov 2001
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01-05-02, 03:52 AM   #2  
I would recommend you use one inch fiberglass rigid board insulation and install three layers. You'll find the 1-inch will be easier to work with and it will allow you to make up any differences, especially with any protruding nails. They come in 4' x 8' sheets. I would also use foam to hold each layer in place. You'll find you only have to tack it in a few places and it sets up fast. Furthermore the rigid board comes with foil on both sides so it'll act as a vapor barrier and radiant barrier. You don't have to worry about condensation inside the boards, because there's not enough air inside them to create condensation, unlike batt insulation. Good luck with your project.

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01-14-02, 02:55 AM   #3  
Insulation Bat Solution

I am currently trying to solve the same problem in my house. The upstairs bedrooms are very cold due to the fact that the old insulation has flattened and deteriorated. I seem to have found a decent way to get fiberglass bat insulation in the sloped and flat section of the ceiling. After a day of trial and error here is what worked best for me. What you need to do is fish a rope from one side of the house to the other. I tried to do this with electircal fish tape(too flexible), then tent poles(too stiff to make the angle), finally I found it, vertical blinds(tape a few together and they become stiff enough to push through yet flexible enough to make the angles. Then I tied the rope to the kraft faced bat. Went back to the other side and pulled the insulation through. This was just an experiment but I think I'm going to use this method rather than cutting all the foam board as you mentioned. The only problem I forsee is getting snagged on the electrical wiring going from the switches to my ceiling fans. Also since I left the old insulation in place I only have about an inch clearance to the roof for ventilation. I might need to install those foam vents to keep the insulation away from the roof. When I find the time I'll let you know how I make out.

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