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OSB laminated with radiant barrier

939 Views 3 Replies 2 Participants Last post by  3onthetree
So we are under construction 2 car garage detached with OSB laminated with radiant sheathing on the external walls. The radiant barrier faces inward against the studs. I’ve also requested to have tyvek applied to the exterior surface. My question is would I be creating a moisture problem within the sheathing? I also want to insulate the walls, should I use foil free insulation?
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First, your location is very important on whether you have predominantly heating days or cooling days. But on a detached garage, it may not be as critical with all the air infiltration anyways.

For a radiant barrier to work it requires an air space (start at 3/4" min) right next to it. Putting the face on the inside makes it a little hard if you are insulating the walls, especially a 2x4 thickness. In this respect you get more out of insulation and airsealing than you do a radiant barrier. Hopefully you didn't pay a premium for the OSB.

If you now decide to leave the insulation out, you would retain the benefits of the radiant barrier, but in a garage you are not measuring that benefit on a conditioned space (like in rooms below an attic), but rather on the objects stored in the garage.

If you had put the foil facing out, like is commonly done in hot regions, then you install furring over that to create the airspace.

Check your product being faced to the inside: If the foil is perforated for moisture, then it probably won't hurt to have a housewrap installed. If the foil is non-perforated (where you also tape all the seams and it is marketed as a barrier to replace housewrap), then you might have problems with condensation behind the insulation (although unconditioned airy garage may not see those conditions often).
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Appreciate the input here . Thank you. Primarily I wish to use the garage as a workshop... wood working etc. I do have a concern about rusting equipment. I’m just north of Allentown Pa. so seasonal temperatures. I’m hoping to put heat in it for wintertime use. The barrier isn’t perforated and I had requested the house wrap just because the vinyl siding was going up on bare OSB. I noticed too that there is no ridge vent . The roof structure is not trusses but the 2 bys 16 on center resting on a lam beam running the 32 foot length. I’m assuming I’ll have to go with rigid board insulation as you say having 2x4 wall studs would be difficult to leave an air gap space between barrier foil and insulation.
I am concerned about moisture as we all know steel equipment and moisture is not a friendly mix. The construction is from a shed company.
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Re: 3onatree

Allentown Pa.
heat in it for wintertime use
The barrier isn’t perforated
Not what you want to hear, but unless you like wet walls and mold, it would be best to flip the OSB radiant to the outside face, cover joints and the holes from removed nails with your product's recommended tape, and use it as an air + water barrier as intended (eliminating housewrap).
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