Durability and Moisture Performance

Codes Research
Contact: Gary Ehrlich
gehrlich@nahb.org
(202) 266-8545

Moisture Performance of High-R Wall Systems. This report documents the moisture performance of wall assemblies in 22 houses built to or exceeding 2015 energy codes or equivalent and equipped with moisture meters in wall sheathing and cavities. The variation in moisture contents and indoor relative humidity through the 2016-2017 winter season is tracked and observations relative to moisture performance documented. The findings provide key data on the performance of 2x6 walls with continuous insulation and with Class II interior vapor retarders. An addendum includes data and findings from the 2017-2018 winter season.

Characterization of Moisture Performance of Energy-Efficient Light-Frame Wood Wall Systems.This report documents the moisture performance of four wall systems: Extended Plate and Beam walls, walls with air leakage versus air sealing, 2x4 walls with various types of exterior insulation, and baseline walls insulated with kraft-faced batts and unfaced batts. The walls were constructed on test huts in a Climate Zone 4A location.

Moisture Performance of Walls. This report documents the moisture performance of wall assemblies in 22 houses built to the 2012 energy codes or equivalent and equipped with moisture meters in wall sheathing and cavities. The variation in moisture contents and indoor relative humidity across a three-year period is tracked and observations relative to moisture performance documented. The wall assemblies studied generally showed good performance, with wall moisture contents highest in the first winter season due to construction moisture but trending lower in subsequent winters.