FYI manufactured home venting

[Dennis DiVito]

I asked the following question about venting the underside of manufactured homes (double wides)

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Should the plastic wrap under the house covering the floor joists and insulation be entirely removed during installation? If left in place wouldn't it trap moisture in the insulation?

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Here is the response

"The plastic material should not to be removed during the installation process. This plastic material is referred to as the "bottom board" of the home. It is required by the HUD Code and its purpose is to prevent insulation materials or any ductwork, that might be constructed below the floor joists, from being exposed directly to the elements, whether or not the home is installed with a skirting material. It also protects the underside of the home during transport to the installation site.

This material also can act as a vapor barrier to prevent moisture which may accumulate underneath the home after placement (either standing water or condensation) from having access through the floor system. If the bottom board is ripped or torn while installation is taking place, it should be sealed or repaired in some nature. Ask the manufacturer or the retailer what materials are appropriate to repair the bottom board material.

Removing the bottom board can also invalidate any warranty that comes from the manufactured home producer once purchased. The manufacturer's installation manual usually has provisions that explain how to protect this material during and after the installation process."

Mark A. Nunn

Vice President - Technical Activities

Manufactured Housing Institute

(703) 558-0665

mark@mfghome.org

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[dlee]

Good information. Thanks, Dennis.

-David