I have a 1950s bungalow that sits on a crawl space. The crawl space is vented and has moisture problems (which I should/will fix, but that's not the main point of this question). R19 insulation is installed between the floor rafters. Some of the floors sit on OSB, while the older/non renovated parts sit on slat subfloor.

The floors are extremely cold and drafty. What are my options to keep the floors warmer and less drafty in the winter?

Will crawlspace encapsulation help? What would be the most effective solution to fixing the cold/drafty floors?


Cap the floor joists with rigid insulation. I'd first make sure the existing insulation is completely filling each joist bay and as expanded as possible (no edge curls, gaps nor compressed sections). Remember, the paper vapor barrier should be facing the living space you are heating or cooling. For a truly draft-free seal there is now a spray foam kit sold for the DIY home owner. Same 2 part spray foam that is used by commercial insulation installers, but in smaller amounts.

  • Will this solution work with the moisture that is typical in a vented crawl space? I am based in the Southeast US – DIYoutube Aug 28 '15 at 17:54
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    Moisture shouldn't have any adverse effect if it is outside of the conditioned house envelope. Moisture can be an issue if you have any gaps inside a warm house. If its cool outside water vapor becomes condensation (liquid water). Sometimes this can lead to mold and framing damage. Reason to check that existing insulation is properly installed. Also you should have ventilation grills spaced in the crawl space exterior walls. If you think they are insufficient you can add powered ventilators to improve air flow/ moisture removal. – ojait Aug 28 '15 at 22:56
  • I hope you found the information provided for your answer helpful. If so, as per Stack Exchanges instructions to all new members.."Voting is central to our model of providing quality questions and answers..". So it would help others whom might have a similar question if you voted for any answer you found helpful. – ojait Oct 13 '15 at 14:58
  • Any idea what it might cost (an expected range) per sq ft to get a pro to do this? In CA, there's a home energy program that will give you up to $6500 back by increasing your home's energy efficiency, but it must be done by a licensed professional. I'd prefer the spray foam over the rigid board insulation – Matthew Levine Jan 7 '16 at 22:37

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