Tim-bor comes in powder form. The powder is dissolved in water and sprayed on wooden sill plates, joists and other interior wooden framing of buildings. It's applied as a 10 percent solution made by mixing 5 pounds of Tim-bor powder with five gallons of water. Spray, let dry, and spray a second coat. Apply each coat at a rate of 5 gallons per 1,000 square feet of wood surface. Tim-bor is colorless, odorless, and won’t corrode nails and other metal structural fasteners. Because Tim-bor can leach out of wet wood, it is limited to above-ground application in dry locations protected from the weather.