Detailing Walls With Rigid Foam
Navigating the challenges of exterior insulation isn’t the nightmare you might think it is.
Synopsis: In this article, builder Steve DeMetrick shares construction and design details for efficient and trouble-free installation of exterior foam sheathing. His method employs Zip System sheathing for structure and air-sealing, 2-in. foil-faced foam for exterior insulation, and a felt-paper weather-resistive barrier behind a rain screen.
Wall construction has changed dramatically since I started in the trades 20 years ago. The 2×4 walls insulated with R-13 fiberglass batts that everyone built back then don’t come close to complying with today’s energy code in climate zone 5, where I live. And even with today’s stricter codes, building just to code is like settling for a D in school. A house that only meets the minimum standard is the worst that can legally be built.
On this house, the combination of 2-in. foil-faced polyisocyanurate exterior foam and 6 in. of fiber insulation create a high-performance wall that exceeds the IRC requirements. But…