Analytical, experimental and numerical analysis of moisture movement in walls exposed to hot and humid climates.

摘要

This dissertation focuses on the experimental test results for heat and moisture migration in walls exposed to hot and humid climates. The primary motivation for this research project was to study the problem of mold and mildew caused by moisture transfer from hot and humid climates into walls of concrete masonry unit (CMU) type construction by diffusion and convective transport by air infiltration. In this study, two types of outside CMU surface treatments were evaluated, bare CMU surface and CMU treated with an elastomeric stucco. The interior surface of the gypsum board was treated using either latex paint, permeable vinyl wallpaper or vinyl wallpaper.; The tests were conducted in two distinct phases. The main objective of Phase-1 was to evaluate heat and moisture transfer by diffusion. This was accomplished by simulating the weather data for Brownsville, Texas during the months of June, July, and August while a negligible pressure gradient was maintained across the walls. In Phase-2, in addition to the diffusion through the test walls, air infiltration was added by maintaining a pressure gradient of 0.05 inches of water column throughout the test period. Neither solar loading nor direct wetting of the surface, such as rain, were considered. In addition to the Phase-1 and Phase-2 testing, data were collected at the end of Phase-2 testing to determine the rate at which the test walls would dry without infiltration present.; Phase-1 test results indicate that an exterior vapor barrier will reduce the moisture migration into the wall and thereby lower the moisture accumulation due to infiltration.; The test results from Phase-2 testing showed that while the exterior wall treatment does have an effect on reducing the total moisture accumulation in the test walls, the interior wall treatment has a much larger impact when infiltration is present.; The Dry-Out test results showed that latex paint treated gypsum board dried out the fastest followed by permeable wallpaper and vinyl wallpaper after infiltration was stopped. This suggests that permeability of the interior surface treatment plays an important role in allowing the wet gypsum board to dry.