Moisture Performance of Energy-Efficient and Conventional Wood-Frame Wall Assemblies in a Mixed-Humid Climate

Long-term moisture performance is a critical consideration for design and construction of building envelopes in energy-efficient buildings, yet field measurements of moisture characteristics for highly insulated wood-frame walls in mixed-humid climates are lacking. Temperature, relative humidity, and moisture content of wood framing and oriented strand board (OSB) structural panel sheathing were measured over a period from mid-November 2011 through March 2013 in both north- and south-facing orientations in test structures near Washington, DC, USA. Wall configurations varied in exterior cladding, water-resistive barrier, level of cavity insulation, presence of exterior continuous insulation, and interior vapor retarder. The combination of high interior humidity and high vapor permeance of painted gypsum board led to significant moisture accumulation in OSB sheathing during winter in walls without a vapor retarder. In contrast, wintertime moisture accumulation was not significant with an interior kraft vapor retarder. Extruded polystyrene exterior insulation had a predictable effect on wall cavity temperature but a marginal impact on OSB moisture content in walls with vinyl siding and interior kraft vapor retarder. Hygrothermal simulations approximately captured the timing of seasonal

[1]  Andreas Holm,et al.  WUFI-ORNL / IBP — A North American Hygrothermal Model , 1995 .

[2]  Achilles Karagiozis.  Application of Advanced Tools to Develop Energy Efficient Building Envelopes that are Durable , 1995 .

[3]  K. Ueno,et al.  Monitoring of Double-Stud Wall Moisture Conditions in the Northeast , 2015 .

[4]  Joseph Lstiburek,et al.  Moisture-Related Durability ofWalls with Exterior Insulation in the Pacific Northwest , 1995 .

[5]  John Straube,et al.  Ventilated Wall Claddings: Review, Field Performance, and Hygrothermal Modeling , 2009 .

[6]  Samuel Glass,et al.  Interior Temperature and Relative Humidity Distributions in Mixed-Humid and Cold Climates as Building Simulation Boundary Conditions , 2010 .

[7]  Achilles N. Karagiozis,et al.  The Hygrothermal Performance of Wood-Framed Wall Systems Using Spray Polyurethane Foam Insulations and a Smart Vapor Retarder in the Pacific Northwest , 1995 .

[8]  Colin Craven,et al.  Exterior insulation envelope retrofits in cold climates: Implications for moisture control , 2014 .

[9]  S. Glass.  Hygrothermal Anaylsis of Wood-Frame Wall Assemblies in a Mixed-Humid Climate , 2013 .

[10]  Samuel V. Glass,et al.  Review of in-service moisture and temperature conditions in wood-frame buildings , 2007 .

[11]  Tenwolde Anton,et al.  ASHRAE Standard 160P-Criteria for Moisture Control Design Analysis in Buildings , 2008 .

[12]  R. Lepage,et al.  Moisture Management for High R-Value Walls , 2013 .

[13]  W. L. James,et al.  Electrical moisture meters for wood , 1958 .

[14]  Tullie Circle,et al.  AMERICAN SOCIETY OF HEATING, REFRIGERATING AND AIR-CONDITIONING , 2013 .

[15]  Hartwig M. Künzel,et al.  Calculation of heat and moisture transfer in exposed building components , 1996 .

[16]  Hr Trechsel,et al.  Overview of ASTM MNL 40, Moisture Analysis and Condensation Control in Building Envelopes , 2001 .

[18]  John Straube and Jonathan Smegal.  Building America Special Research Project—High-R Walls Case Study Analysis , 2009 .

[19]  John Straube,et al.  Building science for building enclosures , 2005 .

[20]  C. Carll,et al.  Decay of Wood and Wood-Based Products Above Ground in Buildings , 1999 .

[21]  William B. Rose,et al.  Moisture Control Strategies for the Building Envelope , 1996 .

[22]  Charles G. Carll,et al.  Effect of Cladding Systems on Moisture Performance of Wood-Framed Walls in a Mixed-Humid Climate , 2010 .

[23]  M. E. Dunlap.  Electrical moisture meters for wood , 1944 .