A complete guide to Larsen truss wall systems for cold-climate eco-builds: why they work, how to design them, step-by-step installation, real cost data from a Nova Scotia owner-build, and how they compare to double-stud and exterior-foam alternatives.
Larsen Truss Walls: Cold-Climate Installation Guide (2026) Larsen trusses are one of the simplest and most owner-builder-friendly ways to get super-insulated walls in a cold climate. Invented in the late 1970s by Edmonton builder John Larsen, they let you build a wall as thick as you need — R-30, R-40, R-50, even R-60 — without specialized tools, without complicated framing, and without bringing in spray foam contractors. This guide walks through what they are, why they work, who they suit, and how to install them. The numbers and decisions come from my actual Nova Scotia build (Climate Zone 6, marine moisture influence); the principles apply anywhere in cold-climate North America from Zone 5 through Zone 8. If you want the chronological story of how I made the decision and then built the trusses, see Build Update 6: Passive House Theory and Larsen Trusses(/blog/build-update-6-the-theory-of-passive-houses-larsen-trusses) and Build Update 7: Building the Larsen Trusses and Adding Siding...