# crawl space insulation



## Gary in WA (Mar 11, 2009)

Welcome to the forum!

You really shouldn’t have any vapor retarder facing paper in your location- zone #3 or #4: “1. Zone 1, Zone 2, Zone 3 and Zone 4 (except Zone 4 Marine) do not require any class of vapor retarder on the interior surface of insulation in insulated wall and floor assemblies.” From; http://www.buildingscience.com/documents/digests/bsd-106-understanding-vapor-barriers

http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_11_sec001_par001.htm

If ducts are in crawl, you should check with your local B.D. for a closed-crawl: http://www.buildingscience.com/docu.../rr-9302-humidity-control-in-the-humid-south/

And another with more guidelines; http://www.buildingscience.com/documents/houseplans/hp-mixed-humid-recommendations
If you already have the facing, and put it down toward the plastic-covered dirt----- you must cover it (asphalt covered paper) against fire with an approved barrier (fiberglass batt, drywall, plywood, etc). The flooring (if plywood or OSB) has exterior glue which is a vapor retarder, adding another (the facing) below could be asking for trouble in a vented crawlspace. With no insulation facing, I would use housewrap (vapor permeable) on the joist bottoms to prevent wind-washing in a vented crawl.

Gary


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## Windows on Wash (Aug 30, 2011)

Good post Gary.

Can't really sum it up any better than that there.


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