Dow rigid insulation installation

[matcnc]

does it really matter which side of the sheathing faces the interior?? I have the letters facing toward the interior. My reasoning was to keep moisture out. The sheathing insulation has a plastic film on one side so I put it toward the skin of the trailer. Hopefully this will work. Please tell me if this is acceptable[/i]

[starleen2]

does it really matter which side of the sheathing faces the interior?? I have the letters facing toward the interior. My reasoning was to keep moisture out. The sheathing insulation has a plastic film on one side so I put it toward the skin of the trailer. Hopefully this will work. Please tell me if this is acceptable[/i]

Rigid foam insulation is not like fiberglass bat insulation. Bat insulation requires that that the fibers Not be compressed so that trapped air cannot conduct heat / cold efficiently - but some air can pass through. Rigid foam works almost the same way with air conduction, but the air is trapped in the foam and the foam sheet is solid - water vapor will not pass easily through it. The type of foam I used had plastic on both sides and I removed it. I've seen other foam sheets with none. I don't see it as being something detrimental to your build (although someone with more experience may predict dire consequences)

[pete42]

here is what I found for houses http://www.ehow.com/how_4869542_install-foam-board-insulation.html

they don't know we are using it in TTT I guess.

pete

[Engineer Guy]

Vapor Barriers are always installed on the habitable side of Insulation. This is to stop warm humidity from the living area from penetrating into the Insulation. Closed cell Foam will likely not be as problematic as Fiberglass or blown-in Insulation. The points made above on ehow.com - and the logic behind Code practices - stand whether it's 70 sq. ft. or 1,700 sq. ft.. Such is Physics.

I'm not predicting dire consequences, but now warm moist air from the living area will meet cooler, drier outside air at the barrier after it penetrates the Insulation. In-wall mold is prevented by having this 'meeting' occur just under the wall covering, be that Drywall, Plywood or Luan, after Insulation moderates the outside air temperature and humidity differential. Some sort of Vinyl-covered interior Wallboard would likely help prevent any problems. Humidity transfer through a Wood Floor might also minimize problems, as might a Fantastic Fan or open windows.

Years ago, a Manufacturer I don't recall came out with pricy interior paint that also served as a Vapor Barrier. It was made for use in older Homes where retrofitting a plastic Vapor Barrier was not practical.

Tyvek, and other exterior House 'wraps' installed under House Siding, 'breathe' to allow humidity transfer while reducing 'wind' infiltration. Interior 6 mil Plastic, and other Vapor Barriers placed just under Drywall, specifically do not breathe or allow humidity penetration. Special Tape is used between plastic pieces to ensure this.

[matcnc]

thanks for the link. I'll try to post pictures later[/img]