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Last Updated: , Created: Saturday, October 27th, 2001

Would installing insulation between the floor joists prevent moisture in the house from a crawl space?

Harold in New Brunswick has a problem with moisture and mould. He has a bungalow with a 2 foot crawl space. There is no insulation in the floor and no vapour barrier under the floor. He asks if installing insulation between the floor joists prevent moisture in the house?

No. Most insulation will not stop the movement of moisture. The easiest, cheapest and most effective (all together believe it or not) is to simply put a plastic sheet over the dirt in the crawl space. This will stop moisture from the soil from evaporating. You can see one of the Reader's Digest graphics that show how to do this. You don't have to seal the edges or do a perfect job. If you cover 95% of the soil, you stop 95% of the problem.

That will stop the worst of the moisture problem. Then you need to think about insulating, preferably around the outside perimeter to keep the heat in.


Keywords: Crawl Space, Condensation, Moisture, Mold, Mould, Vapour Barrier, Moisture Barrier, Insulation

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