Construction Guidelines for High R-Value Walls without Exterior Rigid Insulation
- Steven Winter Associates, Inc., Norwalk, CT (United States). Consortium for Advanced Residential Buildings (CARB)
High R-value wall assemblies (R-40 and above) are gaining popularity in the market due to programs such as the U.S. Department of Energy Zero Energy Ready Home program, Passive House, Net Zero Energy Home challenges in several states, and highly incentivized retrofit programs. In response to this demand, several builders have successfully used double-wall systems to achieve higher R-values in thicker, framed walls. To builders of conventional stick-framed homes, often one of the most appealing features of double-wall systems is that there are very few new exterior details. Exterior sheathings, structural bracings, house wraps or building paper, window and door flashings, and siding attachments are usually identical to good details in conventional framed-wall systems. However, although the details in double-wall systems are very similar to those in conventional stick framing, there is sometimes less room for error. Several studies have confirmed colder temperatures of exterior sheathing in high R-value wall assemblies that do not have exterior rigid foam insulation. These colder temperatures can lead to increased chances for condensation from air exfiltration, and they have the potential to result in moisture-related problems (Straube and Smegal 2009, Arena 2014, Ueno 2015). The information presented in this guide is intended to reduce the risk of failure in these types of assemblies, increase durability, and reduce material brought to landfills due to failures and resulting decay. Although this document focuses on double-wall framing techniques, the majority of the information about how to properly construct and finish high R-value assemblies is applicable to all wall assemblies that do not have foam insulation installed on the exterior of the structural sheathing. The techniques presented have been shown through field studies to reduce the likelihood of mold growth and moisture-related damage and are intended for builders, framing contractors, architects, and consultants involved in designing and building super-insulated homes. The information is applicable to both new construction and gut-rehabilitation projects in Climate Zones 5 and higher.
- Research Organization:
- Steven Winter Associates, Inc., Norwalk, CT (United States). Consortium for Advanced Residential Buildings (CARB)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Building Technologies Office (EE-5B). Building America Program
- DOE Contract Number:
- AC36-08GO28308; KNDJ-0-40342-05
- OSTI ID:
- 1324032
- Report Number(s):
- DOE/GO-102016-4783; 7464
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CARB
Consortium of Advanced Residential Buildings
SWA
Steven Winter Associates
Inc.
residential
residential buildings
Building America
High-R walls
moisture risk mitigation
double wall assemblies
moisture related problems
condensation
air tight construction