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Insulation below subfloor in crawl space

17 years ago

Being in California where it's mostly dry and not terribly cold in the winters, is it worth the trouble to install insulation below the subfloor to help with minimizing heat loss? In addition, is it really necessary to place a vapor barrier (plastic sheeting) over the dirt below the subfloor before inistalling engineered hardwood? Isn't the 15# felt sufficient?

Thanks in advance...

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Comments (3)

floorguy
17 years ago
As long as you have the moisture in the crawl space under control. there is nothing wrong with putting insulation between the joists.

The crawl space does need a moisture barrier over the soil in the crawl space, to redirect moisture vapors, or it will make the joists and the underside of the plywood subfloor wet, while the interior of the home is dry. If a flooring board once installed has a higher moisture content on the bottom from a humid crawl space, compared to a dry top side from a conditioned interior, you will get a cupped floor.
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remodeling
Original Author
17 years ago
floorguy...Thanks for the input...

The crawl space is vented and even though it looks very dry and does not get wet or damp, there will always be moisture vapors coming up from the ground? laying plastic sheeting will be quite a chore (limited crawl space) but if it's highly recommended then I'll have to reconsider. I've already installed most of the flooring throughout the house and have just opened up a section of the family room to try to fix a few squeaks and thought I should take advantage of maybe insulating if the benefit outweighs the amount of work. Does insulating between the joists really help with the minimizing heat loss? Thanks!
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angier_2007
17 years ago
Think of it as preventing the cold damp air from coming up from the crawl space into your living space. Laying plastic sheeting is a chore but can be made easier if you cut your sheeting first outside of the crawl. I did mine myself with help from my friend. One person on each corner would make it even easier.
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