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 mould 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, recommends practices for controlling moisture accumulation in walls exposed to hot and humid climates.

KEYWORDS: moisture, walls, tropics, subtropics, content, water vapour permeability, wallpaper, buildings, materials, room temperature, USA, calculating, computers, vapour barriers, air barriers.