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Q&A: Moisture Content in Insulation

Posted: September 2, 2016


We were impacted by the recent flooding, but the water did not get into our house. It appears that the water got high enough to "wick" into the insulation under the house. In most of the places we've checked the insulation, the insulation is damp on the bottom, but it's dry on the top portion of the insulation. We know something needs to be done, but aren't sure how to proceed. The house is 5' off the ground and is on a concrete slab.

Do you have any suggestions? Should we rip out the old and spray in new insulation?


Once conventional insulations become wet they lose their ability to keep the outdoor temperatures from entering the inside of your home. In addition, the wet insulation will support the growth of microbials and become so heavy that it eventually falls out of its original place and sags below the subfloor making it no longer effective. 

I suggest removing all the insulation, let the floor assembly dry to a moisture content of 15% or less, and then install the following: air barrier, thermal barrier, and vapor retarder. Essentially, you have two products that fit that description:

  • Two inches of closed cell spray polyurethane insulation, or
  • Two inches of Foiled faced poly-iso rigid insulation board. 

See the link of a blog posting from Paul's House website that describes Insulating Raised Homes Please contact Louis Triay from Energy and Comfort Solutions for any questions or a written proposal for spray foam insulation.

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