Vapor or air barriers in outer walls?

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Joined: Wed Sep 23, 2020 4:43 pm

mobile home walls.jpg
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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Location: Weedsport, NY

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."
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Joined: Wed Sep 23, 2020 4:43 pm

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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Joined: Thu Jan 06, 2011 12:39 am

Through this thread has been dead for a while I figured I'd throw my comments here in order to help anyone who comes along...

In general you want an air barrier, a vapor RETARDER and a water RESISTIVE barrier in pretty much all exterior walls. The order and configuration, as well as materials that will fill the bill, ALL depend on where one is located and what framing, sheathing and siding is being used.

Here's current code (the aims are the same for any residential dwellings, be they manufactured or not [new manufactured homes have to meet the same requirements- code version depends on local jurisdiction]): ... rior-walls
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