Vapor or air barriers in outer walls?

Repair help for the do-it-yourselfer.
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Posts: 2
Joined: Wed Sep 23, 2020 4:43 pm

Sat Sep 26, 2020 7:57 pm

mobile home walls.jpg
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We are going to install R15 Rockwool in the outer walls of our 1979 single-wide mobile home. It is located in the Pacific Northwest in the woods, entirely off-grid. The house will be heated by a wood stove.

What we don't know is how we should install vapor and/or air barriers or even if we need both or only one.

Where should the barrier(s) be placed? Should we install it between the insulation and the outer metal wall, on the inside of the insulation, or both?

Part of the irregularity with our install is that we are not planning on installing drywall or plywood: we plan on planing pallet wood for our walls. Is that incredibly stupid? Should there always be drywall or plywood installed?

Any help would be greatly appreciated. We are doing this all ourselves and it's not exactly the way things would normally be done.

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Joined: Wed Feb 28, 2007 8:01 pm
Location: Weedsport, NY

Mon Sep 28, 2020 6:45 pm

This is the dilemma faced by most manufactured home owners. Traditional construction calls for a barrier (tyvek type) outs the studs and a vapor barrier inside the studs. We all know that manufactured homes have a tendency to develop rotted rim joists and the bottoms of some studs due to water leakage so anything you can do to prevent damage is a plus.
To do it the "proper" way the outer skin should come off and house wrap installed under it. then insulation and a vapor barrier. You will have to make the call how deep you want to go.

"If I can't fix it, I can screw it up so bad no one else can either."

Posts: 2
Joined: Wed Sep 23, 2020 4:43 pm

Tue Sep 29, 2020 12:43 am

Thank you Greg. That does help some. We've actually replaced some of the rim joists and some of the studs already due to what you mentioned.

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