A new look at moisture control in low slope roofing

Conference · Sat Mar 01 04:00:00 EST 1997

OSTI ID:527934

Desjarlais, A O ^[1]; Byars, N A ^[2]

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1. Oak Ridge National Lab., TN (United States)
2. Univ. of North Carolina, Charlotte, NC (United States). Engineering Technology Dept.

One of the criteria for a moisture-tolerant roof is that moisture accumulation in a roofing system must not be large enough to cause condensation within the roof, since this can damage the insulation and reduce its effectiveness. Failing this criterion would require the inclusion of a vapor retarder into the roofing system. We have tested this requirement using computer simulations for a series of new roofing systems and environmental conditions. This paper uses the database from those simulations to develop a simplified method to predict condensation control using only variables associated with the roof and environmental conditions. This method assesses the potential for condensation within the roof assembly without having to perform a computer simulation. Using the computer simulation output data, the moisture accumulation inside each of the roofing systems was calculated. A critical threshold of moisture accumulation was assigned by analyzing the roofing systems which fail to prevent condensation from occurring within the roofing system. An empirical equation for moisture accumulation as a function of roof system and environmental condition variables is developed. The moisture accumulation calculated using this relationship correlates well with the moisture accumulation based on the results of computer simulations. The ability of these two different relationships for moisture accumulation to predict condensation control using the established critical threshold is assessed. Accuracy of both methods is over 95%.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USDOE Assistant Secretary for Energy Efficiency and Renewable Energy, Washington, DC (United States)
• DOE Contract Number: AC05-96OR22464
• OSTI ID: 527934
• Report Number(s): CONF-970935--1; ON: DE97004111
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
CALCULATION METHODS
MOISTURE
PERFORMANCE
ROOFS
SIMULATION
THERMAL EFFICIENCY