Thermal bridging with spray foam insulation
If you have 2×12 rafters and are installing approximately 5 inches of foam do you need to encase the rafters in foam to prevent heat loss through the top of the 1 1/2″ of rafter? Or is the heat loss so insignificant that totally encasing the rafter in foam would prove to be unnecessary?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part