Thermographic imagery revealed empty wall cavities (top), air infiltration around windows (center), and cold spots around framing members like corners and plates (above).
The wall cavities were first dense-packed from the outside with blown cellulose insulation.
The crew stripped off the old cedar shingle siding, focusing on one side of the house at a time to protect the exposed walls and insulation from the weather.
After removing trim from the old windows (this frame was fitted with new jamb liners and replacement sash), crew members filled voids and gaps around the frames with spray foam.
The frames were taped to the sheathing with self-adhering flashing tape.
New cedar sill extensions were applied to the sills.
The frames were fitted with new 1 3/8-inch-wide Azek jamb extensions.
The walls were wrapped with 1-inch-thick sheets of polyisocyanurate foam, which adds R-6 to the wall assembly and acts as an air and vapor barrier and drainage plane. All joints — including gaps between the rigid foam and jamb extensions — were foamed.
All joints were sealed with flashing tape.
Battens ripped from 3/8-inch plywood were fastened through the foam and sheathing into the wall framing to provide solid nailing for the fiber-cement siding and create a drying airspace behind it.
Strips of 3/8-inch-thick Cor-A-Vent installed along the base of the wall between the battens keep out insects.
Workers trimmed the corners with one-piece Azek PVC corner boards.
To reduce maintenance costs, the homeowners opted to replace the weathered cedar shingles with new factory-painted fiber-cement lap siding.