Adding an addition onto a 100 year old house. Insulation, windows, heating, etc. were updated about 30 years ago and the house is tight and efficient. The house has alum. siding. To blend in, we intend to tear off all the siding on that side of the house; the same siding pattern is available. The current structure has has under the plaster— a film of visqueen, then fiberglass insulatiion, then 1/2 inch plywood, then 15 pound felt, lap siding, and finally aluminum siding with styrofoam backing but furred out from the old siding with lathe.
question: we intend to tear off the aluminum siding, lath , plus the old lap siding down to the plywood. As we reinstall new aluminum siding we could use Typar house wrap or could go with 1 inch 4 X 8 sheets of blueboard or styrofoam insulation and tape joints. If we do this is this too tight and asking for trouble with water trapped behind the blueboard? Or should we put on blueboard insulation WITHOUT taping joints and then Typar on top? The advantage of using the blueboard is also that it would equal the same distance out fromthe 1/2 inch sheathing as the siding and lath we will be tear off and match the other parts of the house.
Replies
No typar, no tape, I'd skip the blueboard as well, the insulation value is R3 ? Whiteboard R.05? and its highly flammable? I'm not up on the toxicology of living in a foam box. Let your house breathe, stay healthy.
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What do you mean by "Let your house breathe, stay healthy"?
To me breathing is being air in and out and at the same time transporting moisture.
None of which you want your walls to do. Much work is done to stop air flow and moisture flow through walls.
"What do you mean by "Let your house breathe, stay healthy"?"
"Much work is done to stop air flow and moisture flow through walls."
I'm saying that you cannot stop the penetration of moisture into an exterior wall cavity. I'm saying that an exterior wall will take on moisture on damp days and that it is critical to allow that moisture to escape on dry days. If moisture cannot escape readily, that exterior wall can become an unhealthy environment and that environment will find a way into the living space. You can't stop Mother Nature, but my, how they try.
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Apparently some have never heard of Air Exchange units.
I agree that removing moisture from the interior living space is of the utmost importance and is paramount for keeping the air tight, newer homes livable. My concerns on this subject are more specificaly directed to the exterior wall cavity.
Think of a thermopane window with a broken seal, it doesn't matter how much that window is heated by the sun, the interior of that window will never dry. Think of how that pertains to exterior wall construction, incoming, outgoing air, where is the air exchange taking place within the wall?
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