Question: “If I lived in an area where termites are a problem like much of the Southeastern U.S., won’t my raised wood floor system be more vulnerable to attack than a comparable concrete slab-on-grade constructed home?” The short answer is NO!
The question is understandable, since termites consume wood, or more specifically any cellulose material (paper, cardboard, or solid wood). The truth is, a home constructed on a concrete slab is just as vulnerable, if not more so, to termite infestation than a comparable home properly constructed on a raised floor.
Subterranean termites are ground dwellers. They rely on ground moisture to survive and thrive. Concrete slab-on-ground foundations rest directly on the damp earth, giving termites a very short commute from their natural habitat to house framing. In addition, slabs often crack, offering termites a virtually undetectable entryway into the house.
On the other hand, a raised floor elevates the structure above the ground, isolated from the moisture source, and away from termite habitat. The raised floor system makes termite detection simple for trained pest control exterminators who can easily inspect underfloor areas.
Treated Framing Adds Value and Protection for Minimal Cost
Finally, if concerns exist over vulnerability to pests, the raised floor system — or even the entire house — can be framed with pressure-treated Southern Pine lumber, structural panels, and other engineered wood components. The “whole house” concept of using pressure-treated wood framing components in high-moisture areas of the home for added protection against decay and termite attack is nothing new.
Informed builders and homeowners have used pressure-treated lumber for optimum protection of structural framing members. In fact, analysis by the Louisiana Department of Agriculture and Forestry indicates that a typical home (about 2,000 square feet) could be framed entirely with pressure-treated components, while adding about 2% to the overall cost of the home1.
Widespread damage by the Formosan termite has put considerably more emphasis on the use of pressure-treated framing, whether in the raised floor system or for the entire framing of the home. The American Wood Protection Association has approved several preservative treatments effective against Formosan termites that are suitable for residential or commercial enclosed (interior) framing applications; refer to Table 5.
For all structural framing uses, pressure-treated lumber must be dried after treatment to a moisture content of 19% or less. To learn more, refer to SFPA’s publication Pressure-Treated Southern Pine.
The use of pressure-treated wood offers homeowners the most practical, cost-effective and safest way to fully protect framing components from termites or fungal decay.
After removal of all scrap wood from the building perimeter, treatment of the soil around the foundation with an approved termiticide is an effective protection against subterranean termites. Properly installed termite shields also provide effective protection. Regular inspection and termite treatment is recommended. Termite shields may be required in certain localities by the building code.
1 Research conducted as part of the Economic Impact Committee of the Louisiana Department of Agriculture and Forestry (a working group organized within the Louisiana Formosan Termite Initiative Project), September 2000.