Weatherproofing wall from the inside?


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Old 05-08-13, 03:07 PM
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Weatherproofing wall from the inside?

I opened up a wall in our 1950s home, removing the plaster from the inside. They didn't use good weather sealing techniques back then.. the exterior side of this section is a sheltered patio with vertical wood siding on the outside (with tiny gaps between the tongue-and-groove siding panels). There is only tar paper inside the wall to keep the weather out. I think this has been a major source of air infiltration into the wall cavity.

Now, after finishing the electrical/plumbing fixes and before putting the new plaster wall back on, I would like to create a better weather seal. Fiberglass wall insulation probably won't do much as a weather seal. So I was thinking if there is some way I can use the foam spray such as Great Stuff. The area is too small of a job to call out a professional foam insulator service (perhaps merely 50 sq ft of wall). If I try to use the foam spray cans, I would need to find a way to sandwich it so it sticks to the wall rather than the globs dropping to the floor, and it might expand too much and become really messy. Is there another way that I'm not aware of? I'm not planning to modify the exterior siding or the existing tar paper layer.
 
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Old 05-08-13, 03:27 PM
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I would assume that behind the tar paper and before you get to the siding that there is some layer of sheathing to give the siding some support. Given that, I would simply use fiberglass faced batt insulation with the paper on the inside facing the living area. Don't thing you will gain anything with cans upon cans of spray foam.
 
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Old 05-08-13, 03:29 PM
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Weatherproofing is the wrong term. What you want is air sealing and insulation. While you could buy a DIY two-part foam kit the cost is high and there is a steep learning curve. You might be best to use solid polyisocyanurate boards cut to easily fit in the stud spaces and then use the small cans of one-part foam to secure them in place and also serve as the air seal.

I know there are several YouTube videos of people that have done this.
 
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Old 05-08-13, 03:56 PM
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You might be best to use solid polyisocyanurate boards cut to easily fit in the stud spaces and then use the small cans of one-part foam to secure them in place and also serve as the air seal.
Yep this is exactly the kind of tip I was looking for. I would like to make a solid air seal, and I imagine this could work..
 
 

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