The 8 Mil Floor Liner is designed to be durable and easy to install. It consists of a heavy-duty inner layer of fiberglass reinforcement sandwiched between two plies of high-strength virgin polyurethane. A 20-by-200-foot roll costs $310 and a 12-by-100-foot roll costs $185. Similar liners are sold in thicknesses of 6, 12, and 20 mils.

Crawlspace Depot, 888/331-9991, crawlspacedepot.com.