Shed Insulation

cyrious

I just put wall heaters in my shed/workshop and now want to insulate it. Do I need to put a vapor barrier over the insulation? I live in WA state with winter temps below freezing. I am going to sheet the walls with MDS board.

jklingel

I believe you'd be best off w/ a moisture retarding system, as I don't think anywhere is Washington is zone 7 or 8, where real vapor barriers are encouraged. This can be accomplished w/ vapor retarding paint and a tight drywall system. The trend is to get away from real vapor barriers as much as possible. You absolutely should use AIR barriers in and out, but the vapor barrier inside will depend on your climate. I would consider some insulation other than fiberglass batts, too; rock wool, cellulose, or cotton. Keep researching and check w/ local city/county engineers. I am not an expert, but have read a LOT the last few years. One good place to read is greenbuildingadvisor.com; buildingscience.com (?) is another. And here, of course. GL. john

cyrious

thanks, I'll give those website a look through.

KennMacMoragh

Yes vapor barriers are used in Washington state, it's cold enough to where they are required. They go on the inside, you can use one of three methods; faced batts, plastic over studs, or PVA primer.

Gary in WA

Depends on where you live in WA. http://www.buildingscience.com/docum...ecommendations
The unit of measurement typically used in characterizing the water vapor permeance of materials is the “perm.” Several classes of vapor retarders are further defined as follows [4]:
·Class I Vapor Retarder: 0.1 perm or less
·Class II Vapor Retarder: 1.0 perm or less and greater than 0.1 perm
·Class III Vapor Retarder: 10 perm or less and greater than 1.0 perm
·Test Procedure for vapor retarders: ASTM E-96 Test Method A (the desiccant method or dry cup method)
Finally, a vapor barrier is defined as:

• Vapor Barrier: A Class I vapor retarder.

From: http://www.buildingscience.com/docum...gs?full_view=1

The asphalt covering on insulation is a vapor retarder, not barrier: http://www.dyplastproducts.com/water..._permeance.htm

Check with your local Building Inspector as to vapor barrier or retarder required: http://www.ecohomemagazine.com/energ...gy-claims.aspx

http://www.energysavers.gov/your_hom.../mytopic=11810

Be safe, Gary

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cyrious

I was thinking of using the bat insulation, I just wanted to be sure that would be good enough. Thanks for the input!!