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Detailed Computer Analysis of the Moisture Performance of Roof Constructions in the U.S. DOE Moisture Control Handbook.


pdf icon Detailed Computer Analysis of the Moisture Performance of Roof Constructions in the U.S. DOE Moisture Control Handbook. (1887 K)
Tsongas, G. A.; Thornton, B. A.; Burch, D. M.; Walton, G. N.

Challenges of the 21st Century. Roofing Technology, 4th International Symposium. Proceedings. First (1st) Edition. U.S. National Roofing Contractors Association, Canadian Roofing Contractors Association, National Research Council of Canada, International Waterproofing Association, CIB, RILEM. September 17-19, 1997, Gaithersburg, MD, National Roofing Contractors Association, Rosemont, IL, 401-416 pp, 1997.

Sponsor:

Department of Energy, Washington, DC

Keywords:

air flow; attics; attic ventilation; building technology; computer modeling; mathematical analysis; moisture; moisture analysis; moisture modeling; moisture performance; roofs; roof cavities; roof ventilation

Abstract:

A new mathematical model, called the MOIST Attic Model, has been used to predict the moisture performance of a current practice site-built prototype house with 15 different roof designs constructed in compliance with the U.S. DOE Moisture Control Handbook in cold (heating), mixed, and cooling (hot and humid) climates. These open attic or cathedral ceiling roof constructions were intended to be the best designs to minimize moisture problems. But prior to this study, their moisture performance had not been checked with a moisture model. Thus this computer simulation study of their performance was undertaken. For each of the 15 roof designs, attention was focused on predicting the peak values of the plywood roof sheathing moisture content and the relative humidity at the bottom of the insulation adjacent to the various ceilings where mold and mildew might grow. Parametric sensitivity analysis was undertaken to determine the effect of a number of variables on the moisture performance of the various roofs. Findings of the study regarding the moisture performance of the 15 designs, as well as roof design suggestions and code implications, are presented.