- Author
- Burch, D. M. | Harrje, D. T.
- Title
- State-Of-The-Art Research Assessment for Residential Attic Condensation.
- Coporate
- National Bureau of Standards, Gaithersburg, MD
- Book or Conf
- Building Thermal Envelope Coordinating Council. Workshop on Moisture Control in Buildings. Proceedings. Sponsored by the Moisture Control in Buildings Research Coordinating Committee. September 25-26, 1984, Washington, DC, 1-9 p., 1984
- Keywords
- residential buildings | attic | condensation | moisture
- Abstract
- A brief synopsis of recent analytical and experimental studies is given. These recent studies lead to the following conclusions. Convective transfer of water vapor into an attic from the living space below often transports more moisture than diffusive transfer through the ceiling construction. Large quantities of moisture are stored in the roof sheathing during cold winter periods and subsequently released during warm spring and summer periods. Solar loading during mild winter can produce desorption of moisture from the sheathing. In view of the inherent protection against attic condensation offered by mositure storage at wood surfaces, it is likely that the current practices of HUD and past practices of ASHRAE for preventing condensation are adequate. However, a comprehensive field survey to assess rigorously the adequacy of these current and past practices is much needed. Mathematical models are needed to extend the results of individual experiments to different attic configurations and different outdoor climates. This paper reviews the formulation of mathematical relationships among physical parameters governing moisture transfer within attics. In order to model completely all moisture-transfer processes, further experimental measurements are needed to quantify attic ventilation rates and convective air flows into the attic from the house below. In addition to models that characterize attic moisture transfer over short time periods, dynamic models for predicting seasonal variations in the moisture content of roof sheathing also need to be developed and experimentally validated.