- Author
- Burch, D. M.
- Title
- Analysis of Moisture Accumulation in the Walls Subjected to Hot and Humid Climates.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Journal
- ASHRAE Transactions: Symposia, Vol. 99, No. Part 2, 1013-1022, 1993
- Report
- DE-93-16-4,
- Keywords
- moisture | walls | climate | construction
- Abstract
- A detailed computer analysis was conducted to investigate the moisture accumulation in walls subjected to a hot and humid climate (Lake Charles, LA). The analysis revealed that the use of low-permeability wallpaper (e.g., vinyl wallpaper) causes moisture to accumulate within adjoining gypsum board. At this location, the surface relative humidity can rise above 80% and approach a saturated state, thereby providing a conducive environment for mold and mildew growth. A variation of parameters was carried out to investigate which parameters are important. Parameters found to have a significant effect included indoor temperature, permeance of the wallpaper, the amount of outdoor infiltration, the permeance of exterior construction, and the initial moisture content of the construction materials. Parameters found to have a less important effect included orientation, insulation thermal resistance, the permeance of exterior paint, and the type of wall construction. Based on the analysis, the following practices for controlling moisture accumulation in walls exposed to hot and humid climates are recommended. Vapor retarders should not be used at interior surfaces. An exterior vapor retarder should be installed in the construction. The infiltration of outdoor air into the construction should be minimized by installing an exterior air barrier and eliminating negative pressurization of the indoor space. Construction with moist materials should be avoided. The indoor space should not be cooled below its design setpoint temperature.