Moisture Risk in Unvented Attics Due to Air Leakage Paths
IBACOS completed an initial analysis of moisture damage potential in an unvented attic insulated with closed-cell spray polyurethane foam. To complete this analysis, the research team collected field data, used computational fluid dynamics to quantify the airflow rates through individual airflow (crack) paths, simulated hourly flow rates through the leakage paths with CONTAM software, correlated the CONTAM flow rates with indoor humidity ratios from Building Energy Optimization software, and used Warme und Feuchte instationar Pro two-dimensional modeling to determine the moisture content of the building materials surrounding the cracks. Given the number of simplifying assumptions and numerical models associated with this analysis, the results indicate that localized damage due to high moisture content of the roof sheathing is possible under very low airflow rates. Reducing the number of assumptions and approximations through field studies and laboratory experiments would be valuable to understand the real-world moisture damage potential in unvented attics.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy Building Technologies Office
- DOE Contract Number:
- AC36-08GO28308
- OSTI ID:
- 1164104
- Report Number(s):
- DOE/GO-102014-4526; KNDJ-0-40341-04
- Resource Relation:
- Related Information: Work performed by IBACOS, Inc., Pittsburgh, Pennsylvania
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
RESIDENTIAL BUILDINGS
HUMIDITY
BUILDINGS
RESIDENTIAL
IBACOS
BUILDING AMERICA
CATHEDRALIZED ATTICS
UNVENTED ATTICS
HYGROTHERMAL ANALYSIS
MOISTURE RISK
CLOSED-CELL SPRAY FOAM INSULATION
ATTIC VENTILATION
ATTIC AIRFLOW PATHS (CRACKS)
ATTIC AIR LEAKAGE
MOISTURE IN UNVENTED ATTICS
WATER VAPOR FLOW RATE
CONDENSATION
CONTAM
WUFI
BEOPT
CFD ANALYSIS
COLD CLIMATE
Buildings