The Logic of the Assembly
Vertical I-joists fastened to the outside of a structural wall create a deep, continuous insulation cavity with minimal thermal bridging — a strategy that works on new frames and as an exterior retrofit over existing walls. The airtight layer typically lives at the original sheathing plane, protected and interior of the new insulation, with the WRB moving to the new outer face.
General, principle-based documentation — fastening schedules and structural questions belong with your design professional of record.
Layers & Components
Airtight Plane
Membrane or taped sheathing at the original wall face — sealed before the outriggers go on.
The Outrigger Cavity
Vertical I-joists forming a deep, continuous insulation zone around the building.
New Outer Face
Fiberboard or sheathing plus WRB at the new perimeter, behind a ventilated cladding gap.
Extended Openings
Windows move outward with the wall — the extension boxes and membrane returns are the key details.
Wrapping a Building This Way?
The desk can help translate the section into a component list.
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