How to Build a Larsen Truss Wall (Step-by-Step)
Step-by-step instructions for building Larsen truss walls: framing, taped sheathing, rainscreen, window flashing, and dense‑packed insulation for Passive House airtightness.
How to Build a Larsen Truss Wall (Step-by-Step) Building a Larsen Truss Wall is an effective way to achieve high-performance insulation and airtightness, especially for Passive House(https://en.wikipedia.org/wiki/Passivehouse) projects. This method combines a structural 2x4 or 2x6 wall with external trusses to allow for uninterrupted insulation, reducing energy use and thermal bridging. Here's a quick summary of the process and key considerations: - Framing: Use a 2x6 load-bearing wall as the structural core. - Sheathing: Apply plywood or OSB as the air and vapor barrier, sealing all seams with high-performance tapes or liquid flashing. - Trusses: Attach 12-inch I-joists or open-web trusses to create a cavity for dense-packed cellulose insulation, achieving R-values of R-36 to R-40 or more. - Airtightness: Ensure airtight sheathing with meticulous sealing to meet Passive House standards (≤0.6 ACH₅₀). - Moisture Control: Add a rain screen with furring strips for drainage and airflow beh...