To evaluate the potential for moisture problems in these walls, R-40 walls were evaluated in six U.S. cities (Houston, Atlanta, Seattle, St. Louis, Chicago, and International Falls) representing a range of climate zones (2, 3, 4C, 4, 5A and 7, respectively). Eight wall types were analyzed, divided into four categories:
- Advance framed wall insulated on the exterior
- Double stud wall with different cavity insulations
- SIP wall with 11.5 “of EPS insulation
- CMU (concrete masonry unit) wall with EIFS insulation
The peak annual moisture content of the wood-based exterior sheathing was used to comparatively analyze the response to the moisture loads for different wall assemblies in each given city. Walls that experienced moisture contents between 20% and 28% were identified as risky, whereas those exceeding 28% were identified as very high risk.