The Logic of the Assembly
A double-stud wall buys extraordinary insulation depth with ordinary lumber — two independent frames with a wide, fully insulated gap between them. The trade-off is moisture sensitivity at the cold outer face, which is why this system leans hard on a smart vapor retarder at the interior, an airtight layer that is genuinely continuous, and drying capacity designed in both directions.
Deep walls are unforgiving of improvisation. Treat this documentation as the general logic, and put your actual section in front of your design professional of record.
Layers & Components
The Deep Cavity
Two frames, one wide insulated gap — dense, void-free installation is the craft.
Interior Control Layer
A smart vapor retarder handling both airtightness and seasonal vapor flow.
Outer Face
Sheathing, WRB, and a ventilated gap that give the wall its drying path outward.
Fresh Air
At this airtightness level, HRV is part of the assembly conversation, not an accessory.
Going Deep?
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