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Individual Highlight

Moisture Control in Crawl Spaces in Louisiana

Homes with raised floors in New Orleans, Louisiana. Samuel V. Glass, Forest ServiceSnapshot : Builders and homeowners in the Gulf Region often ask how to insulate a crawl space to avoid moisture problems. The Forest Products Laboratory (FPL), in cooperation with Louisiana State University Agricultural Center, monitored conditions in a dozen homes in New Orleans and Baton Rouge to provide research-based answers. We evaluated six different insulation systems on the basis of their ability to prevent moisture build-up in floors.

Principal Investigators(s) :
Glass, Samuel V. 
Research Location : Gulf Region
Research Station : Forest Products Laboratory (FPL)
Year : 2011
Highlight ID : 286


In flood-prone areas, elevating the floor system of a building above the anticipated flood level can significantly limit the extent of property damage associated with flooding. In hot and humid climates, such as the Gulf Coast region, homes have long been constructed with raised floors on crawl space foundations. Recent changes to building energy codes require floors to be insulated. The majority of residential buildings in the Gulf Region are now air-conditioned. The combination of floor insulation and air-conditioning, however, may put floor systems at risk for summertime moisture accumulation and related problems such as mold growth, decay, corrosion, and expansion/contraction damage. In response to a research gap and regional need, researchers from the Forest Products Laboratory, in cooperation with Louisiana State University Agricultural Center, monitored moisture and temperature levels in a dozen homes in New Orleans and Baton Rouge, Louisiana. This research confirmed several trends that were expected, relating to the effects of summer air-conditioning temperatures and impermeable interior floor finishes. It was found that foil-faced rigid foam board and closed-cell sprayed polyurethane foam insulation performed well, keeping subfloors from accumulating moisture. This work provides a research basis for builders, contractors, homeowners, architects, and building officials to make informed decisions.

Forest Service Partners

External Partners

  • Louisiana State University Agricultural Center

Program Areas