The Logic of the Assembly
Most existing wood-frame buildings can be meaningfully improved from one side — which side depends on the project. Re-siding jobs open the exterior for a new weather-resistive barrier, exterior insulation, and taped sheathing; interior renovations put the smart vapor retarder and air-sealing work inside. This system documents both paths and the decision points between them.
General guidance only — the right path for your building is a call for your design professional of record.
Layers & Components
Exterior Path
New WRB over existing sheathing, taped seams, and continuous exterior insulation under the new cladding.
Interior Path
Smart vapor retarder as the airtight layer, sequenced ahead of services and finishes.
Openings
Window connections detailed to whichever layer is airtight — the most common retrofit leak point.
Fresh Air
Tightening triggers the ventilation conversation — plan the HRV alongside the envelope work.
Which Path Fits Your Project?
Send the section and the scope — the desk will walk both options with you.
Ask the Spec Desk