NOTE: There is an Addendum to this report summarizing the results of extended monitoring that continued through April of 2018.
This research examines the moisture characteristics of high-R wall systems as part of a broader effort to offer solutions that increase builders’ confidence with the adoption of energy-efficient technologies. The high-R walls feature increased wall insulation levels, reduced wall air leakage, and often reduced permeance of material layers. Wall assemblies are subjected to various moisture loads, such as bulk water, built-in moisture (construction moisture), water vapor, and capillary transport through materials in contact with water or in contact with the ground.
The objectives of the research include: (1) demonstrating the moisture performance of various high-R walls, (2) identifying wall systems with marginal moisture performance and recommending a set of improvements, and (3) developing a set of design criteria that ensures the durability of high-performance walls. The research extends across cold climate zones where the wall construction is designed to meet substantially increased thermal performance and whole-house air sealing levels.