MAISON COCAGNE HOUSE - Second Floor Details

Maison Cocagne House is designed with double 2x4 insulated, exterior stud walls separated by a 3-1/2 inch fully insulated space to isolate the exterior walls from thermal bridging. The outside double stud walls would be erected prior to construction and erection of the interior stud walls. The inside stud walls are designed to be load bearing while the outside stud walls are designed to carry the exterior finish. The cold side of the inside stud wall is completely covered in a 6 mil vapor barrier then sheathed with 1/2 inch CDX plywood sheathing to provide lateral bracing as well as protect the vapor barrier. Red dashed line shows location of the 6-mil vapor barrier in the wall system. Red dots show locations where barrier is sealed with acoustical caulking. Experience has shown that the vapor barrier can be safely installed inside the wall as long as 2/3 of the insulation is on the cold side of the barrier. Locating the vapor barrier at the cold side of the inside stud wall allows for installation of electric without penetrating the vapor barrier. The cold side of the outside stud wall is sheathed with 1/2 inch fiberboard sheathing, then covered with house wrap. The design allows for the walls to be framed and insulated on the floors and lifted in place using wall jacks. A perimeter truss with 2x4 vertical blocking in line with the 2x4 wall studs above and below is required to carry the loads to the foundation. Details for optional balloon framing and openings are provided in the links and will be discussed later.