In most parts of the country, rigid insulation installed below grade is susceptible to termite damage. Bora-Foam is different, says its maker. The polystyrene panel is infused with the same nontoxic insecticide used in the company’s flagship product, Bora-Care. Layers of 3-mil poly on both sides of the panel reduce vapor permeance and prevent the preservative from leaching out. Bora-Foam comes in 2.5-inch (R-11) and 3.75-inch (R-16) thicknesses. A 4-foot-by-8-foot-by-2.5-inch panel costs about $30. Nisus Corp., 800/264-0870, nisuscorp.com