Insulation and vapor control layers / by Scott Newland

The spray foam insulation is about complete, and the vapor control layer is about half installed.  The VCL is comprised of both a standard 6-mil polyethylene sheet at the vented attic space (where it will covered by drywall from below and about a foot and a half of blown cellulose insulation above) and a "smart" membrane from CertainTeed that has variable permeance depending on the seasonal humidity.