Posted on April 18, 2012 by Scott Gibson
in Q&A Spotlight
Wall assemblies that incorporate rigid foam insulation over exterior sheathingMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen.
, followed by furring strips and siding, are becoming common. The extra layer of insulation helps reduce thermal bridgingHeat flow that occurs across more conductive components in an otherwise well-insulated material, resulting in disproportionately significant heat loss. For example, steel studs in an insulated wall dramatically reduce the overall energy performance of the wall, because of thermal bridging through the steel.
through wood framing, and the furring strips create a ventilation space behind the siding that promotes drying.