Conceptual Reference Database for Building Envelope Research Prev
Next

Moisture control in low-slope roofing: a new design requirement

Desjarlais, A. O., Christian, J. E. and Byars, N. A.

http://www.ornl.gov/roofs+walls/articles/wetroof/index.html,

Desjarlais, A. O., Christian, J. E. and Byars, N. A."Moisture control in low-slope roofing: a new design requirement", http://www.ornl.gov/roofs+walls/articles/wetroof/index.html,.
Abstract:
Historically, moisture control in low-slope roofing has been limited to the selection of a membrane material to prevent moisture from entering the roofing system from the climate side and a simplified assessment to determine whether the roofing system requires a vapor retarder to limit moisture ingress from the building interior. Although most roofing systems fail due to leaks, the existing moisture control strategy does not include any requirements that deal with the removal of moisture once it has entered the roofing system.

Prescriptive requirements for a new moisture control strategy are proposed. The new moisture control strategy not only critically reviews the need for vapor retarders but also addresses the issue of moisture removal from low-slope roofs. Based on a large database of finite difference modelling results, algorithms are presented that allow the roofing practitioner, with the help of a little algebra, to determine if his (her) roofing system design requires a vapor retarder or if the system can be modified to enhance its tolerance for small leaks.

This paper will review existing moisture control guidelines, compare these guidelines with the proposed moisture control strategy, illustrate by example how modelling results were obtained, describe the process employed to develop the algorithms, and demonstrate how these algorithms can be used to design a moisture tolerant low-slope roof.

This publication in whole or part may be found online at: This link has not been checked.here.
Related Concepts

Author Information and Other Publications Notes
Desjarlais, A. O.
Program Manager, Building Materials and Structures, Oak Ridge National Laboratory, Bethel Valley Rd., Bldg 3147, Oak Ridge, TN 37831-6070, e-mail: yt7@ornl.gov
  1. An educational hygrothermal model: WUFI-ORNL/IBP
  2. Investigation of common thermal bridges in walls
  3. Laboratory measurements of the drying rates of low-slope roofing systems
  4. Moisture studies of a self-drying roof: tests in the large-scale climate simulator and results from thermal and hygric models
  5. Moisture: its effects on the thermal performance of a low-slope roof system
  6. Self-drying roofs: What? No dripping!
  7. The whole wall thermal performance calculator-on the net
  8. Water-vapor measurements of low-slope roofing materials
  9. Whole wall rating/label for structural insulated panel: steady-state thermal analysis  
Christian, J. E.
Oak Ridge National Laboratory
  1. Laboratory measurements of the drying rates of low-slope roofing systems
  2. Moisture: its effects on the thermal performance of a low-slope roof system
  3. The whole wall thermal performance calculator-on the net
  4. Whole wall rating/label for structural insulated panel: steady-state thermal analysis  
Byars, N. A.
University of North Carolina Charlotte
     


CRDBER, at CBS, BCEE, ENCS, Concordia,