Moisture Performance of High-R Wall Systems

Published Thursday, April 19, 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.

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The addendum is intended to complement the Moisture Performance of High-R Wall Systems report. This Addendum summarizes the results of extended monitoring that continued through April of 2018. The goal of the extended monitoring is to capture the performance through an additional winter season, after the construction moisture had an opportunity to dissipate, so that the observed results are representative of expected long-term trends in wall performance. Monitoring through an additional year also provides data for a different set of climatic and indoor conditions.

Download the 2019 Addendum