Design the house to avoid wood and rigid foam insulation in soil contact; shed and drain water away from the walls, windows and foundation; eliminate hidden pathways by subterranean termites; make it easy to inspect and retreat; and use termite-resistant materials. Inspections may be carried out under raised houses but not under slabs. Refrain from designing a flat roof. Extend roof overhangs at least 18 inches; 2-foot overhangs are recommended. Factors other than low cost and appearance must be considered.
PRETREATMENT OF SOIL
Pretreatment involves treating the piers or the soil that is under the slab with a labeled, liquid termiticide. A pretreatment contract requires that the pest control operator treat under the slab and then, within one year (after landscaping has been completed), come back and do a conventional trench and treat or baiting (if a bait and chemical treatment contract is involved).
A slab is a barrier in itself. A monolithic slab can serve as a termite barrier. Prevent cracks in the slab by compacting the soil that will be under the slab, using a low water-to-cement ratio mix, not overworking the surface during finishing and allowing sufficient wet curing time. Any crack or hole in the slab, including holes for pipes and bath traps, is a potential route of entry for subterranean termites. Consider adding termite shield collars around pipes and foundation perimeters to block hidden pathways.
Build the house to eliminate wood-to-soil contact, eliminate all sources of moisture in or around the house, eliminate hidden access by subterranean termites, provide easy treatment and inspection and use termite-resistant materials. Make sure the site is prepared before soil treatment, the pretreatment is done properly and not disturbed. Durable 6 mil plastic sheeting should be laid over the treated soil and draped in the grade beam trenches up to grade to keep ground moisture from soaking into and wicking through the slab. Do not leave wooden form boards, grade stakes, concrete and bricks around the slab or driveways. Use grade stakes or form boards made from materials other than cellulose. Avoid using wood spacers in cold joints and expansion joints. Make sure at least 6 inches of slab are showing after landscaping (so design it at least 8 inches above grade). Do not fill porches with soil. Do not bury wood or other construction materials such as leftover concrete and brick.
Keep plants a minimum of 3 feet from houses. Do not disturb the treated soil. Use termite-resistant materials and mulches near the house. Do not transport termite-infested wood, plants, mulch or soil. Mulches containing cellulose provide food for termites and, if used in the landscape, must be used properly. All mulches modify temperature and moisture conditions favorably for termites.
When restoring storm-damaged or flooded homes, consider spraying the wood in exposed wall cavities with borate solutions before replacing insulation and drywall. Surface treatments do not offer total wood protection, but they may provide effective deterrence to both termite and surface mold formation.