Save Energy with Rigid-Foam Insulation

Exterior siding is typically applied directly on top of housewrap covered plywood or OSB sheathing. But a growing number of builders interested in energy-efficient construction are singing the praises of using rigid-foam insulation between the wall sheathing and the exterior siding, creating a continuous insulating layer. Contributing editor Rick Arnold explains why this extra investment in labor and materials has a significant long-term payoff and tells how to detail the installation. A sidebar compares the three main types of foam insulation: expanded polystyrene, extruded polystyrene, and polyisocyanurate.