reflective insulation as vapor barrier


Old 03-31-08, 04:48 AM
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reflective insulation as vapor barrier

This is the foil on 2 sides and bubble wrap center type insulation. I have been reading everywhere about its great r values when installed properly and how great a vapor barrier it is suppose to be but can not see anywhere if this product can actually be used on a dirt crawl space floor.
I have a closed crawl with 2" ridgid insulation on the walls and a 6 mil on the floor. No insulation in the floor joists or any vapor barrier on floor joist section. The old owner had apparently pulled out the old floor joist insulation because it held moisture or whatever. I am running a dehumidifier in the crawl space. In the winter in North Carolina the space above this crawl space has freezing floors. I was thinking of using the refectix insulation as a vapor barrier and doing spray foam or batt in the floor joists. When I say cold I mean the section of the house over the crawl is about 3 degrees colder than the rest of the home. Any thoughts on this and the reflectix as a vapor barrier?
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Old 03-31-08, 05:25 AM
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Not sure which part of NC you are in (I'm about 8 miles south of Hayesville on the Georgia side), but IMO, reinstalling the batt insulation in the joists is the best bet. Probably pulled due to moisture, then all the walls were insulated, then poly on the floor, and never replaced. Install kraft faced insulation between the joists with the vapor barrier up, and use spanner bars to hold up the insulation. In your post you mention installing it on the crawl space floor --no -- the poly will do its job at this point. Do you have your foundation vents closed in the winter?
Old 03-31-08, 05:59 AM
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R value is very poor from the metal
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