Post Seal self-adhesive waterproofing is a 12-inch-wide impermeable membrane designed to prevent moisture intrusion and rot damage at the most vulnerable part of a deck (or fence) post: ground level. Simply wrap the material around the post in such a way that the top of the membrane extends 2 to 3 inches above the ground, then proceed with normal installation. A 12-inch by 18-foot roll (enough to seal a dozen 4x4s) sells for $14.95. Post Seal also comes in a 109-foot-long bulk roll. Cofair Products, 800/333-6700, cofair.com
