Does spray foam insulation require a vapor retarder?
Because all spray foams form a complete air barrier when installed, they stop the vast majority of moisture problems that can occur due to condensation….up to 99% according to many studies. While Icynene LD-C-50™ and LD-R-50™ are excellent air barriers, they are not vapor barriers. According to the state of Wisconsin building codes, a separate vapor retarder may still be required. A low vapor retarding paint/primer (perm rating below 1 perm) is recommended to be applied to the finished surface of the drywall to fulfill these requirements. Because of its lower vapor permeance, Icynene MD-R-200™ will generally not require any type of separate vapor retarder.
