Resources & FAQ

XPS gets much of its insulating value from blowing agents trapped in the foam, and those gases escape over the years. EPS insulates with trapped air, so there's nothing to escape. In a 15-year below-grade study, EPS kept 94% of its R-value and XPS kept 52%. XPS also held nearly four times as much water.

For the same reason a metal roof costs more than three-tab shingles: it's a better product and it lasts. The difference is you can replace a roof later. You can't replace what's under your slab. You only do it once, so do it right.

Houses, garages, and most slabs over rebar or mesh use 15 PSI. Shops with tractors or heavy equipment, commercial garages, and engineered jobs step up to 25 or 40 PSI. 60 PSI is for industrial loads and cold storage. On big or heavy-equipment jobs, check with your engineer. Not sure? Ask us and we'll help you pick.

Speed and fewer seams. Each 4x24 run covers 96 square feet, 3x a 4x8 sheet, so you handle a third as many pieces and tape a third as many end joints. It ships folded into a 4x4 cube and opens right over your grade, and the folds every 4 feet help it lie flat.

Yes. Lexar has a 6-mil vapor barrier built in: 3-mil poly film laminated to each face. Tape the seams and there's no separate layer of plastic to roll out underneath.

Yes. Lexar is treated with Preventol®. Termiticide is built in and protects your home from termites.

Rigid foam made for below-grade use, and one that keeps its R-value in wet, buried conditions. In a 15-year below-grade study by the EPS Industry Alliance, EPS kept 94% of its R-value while XPS (pink and blue foam board) kept 52%. Lexar is EPS made for under the slab: 4x24 fanfold runs with a 6-mil vapor barrier and a 6-inch PEX grid built in.

Yes. Without insulation under the slab, much of the heat from the tubing goes down into the ground instead of up into the room, so you pay to heat the soil. Lexar's printed 6-inch grid also lays out the PEX, which staples straight into the board.

Each Lexar fanfold run is 4 feet by 24 feet, or 96 square feet: three times a 4x8 sheet. A 40x60 slab takes 25 Lexar sheets compared with 75 sheets of 4x8, with a third of the end joints to tape.

About R-4.2 per inch at 75°F (R-4.4 for 60 PSI), rising to R-4.6 to R-5.0 per inch at colder temperatures. 2 inches is the most common thickness. Lexar comes in 15, 25, 40 and 60 PSI.

Through our network of building suppliers across the country. Request a quote and the Lexar team will get you a price and connect you with the right dealer, or call one of the dealers on the map yourself.