A mass timber wall starts with three advantages before any insulation goes on.
- Airtightness. Solid, large-format panels leave few seams, and taping those seams is quick work.
- Thermal resistance. Cross-laminated timber (CLT) carries roughly R-1 per inch of thickness on its own.
- Code treatment. Used as a wall, CLT can qualify as a mass wall, like a log wall, which some codes treat with a reduced insulation requirement.
Almost every mountain home still needs insulation. The question is where. Cavity walls add parts and hide the timber, so the better answer for an exposed interior is continuous exterior insulation, sometimes called outsulation: a rigid wood-fiber envelope outside the panel, then the rain screen and cladding. The panel stays visible inside, the envelope stays continuous outside, and the wall has fewer pieces.
Above the walls is the roof, and on an A-frame the roof is most of the building.
Adapted with permission from a note by our colleagues at Red Falls Timber Co.
