• Manufactured by InSoFast
• 888-501-7899; www.insofast.com
• Cost: $1.55 to $1.90 per sq. ft.
For a number of years, I've finished below-grade basements by installing sheets of 2-in.-thick foam on the walls, taping the joints to make the assembly airtight, then framing a stud wall on the inside to which I attached drywall. InSoFast speeds up and simplifies the process.
The back side of each 2-ft. by 4-ft. by 2-in.-thick expanded-polystyrene (EPS) panel has vertical channels for water drainage and horizontal channels so that you can snake electrical wiring after the panel is in place. The tongue-and-groove edges of each panel also interlock so that you can gang together whole wall sections flat on the floor, tilt them into place, and adhere them to the foundation walls with foam-board adhesive. Paperless drywall is then attached directly to the integral fastening strips; there's no need to frame a stud wall. The result is a 21.2-in.-thick wall insulated to R-10.
Photo by: Krysta S. Doerfler Photo by: InSoFast