Moisture in buildings is probably one of the most investigated, discussed, reviewed, and researched challenges in building design and construction. There are good reasons for this. Consider the Building Assessment Survey and Evaluation (BASE) study that was conducted by the US Environmental Protection Agency (EPA) in the 1990s. It found that among the randomly selected public and private office buildings studied across all 10 climate zones in the United States, 85 percent had been damaged by water at some point, and 45 percent had leaks at the time data was collected. That data indicates that most buildings are likely to experience some form of impact from unwanted or excessive moisture accumulation. Those conditions can lead to serious problems, such as the degradation, deterioration, or even failure of building materials, development of mold and mildew, and possible risks to human health and safety. Repairing any of these conditions after the building is constructed and occupied typically involves opening up construction assemblies, which is disruptive, time-consuming, and costly. Hence, it is no wonder that there is great interest in understanding how moisture can be controlled in buildings at the outset to avoid any or all of these potential problems and risks.

Photo courtesy of Xypex Chemical Corporation

Water and moisture can come from a variety of places and be a problem for multiple parts of a building. Controlling where moisture does and doesn’t go is critical to the successful performance of a building and achieved by focusing on products and systems with the right capabilities. Pictured is 60 Holborn Viaduct located in London.

The Whole Building Design Guide (WBDG), a program of the National Institute of Building Sciences, provides some of the best, objective, state-of-the-art thinking on this topic. It identifies three main causes of moisture movement, namely, water impingement or leakage (as in a roof, wall, or floor system), movement of moist air (through gaps or openings in roofs, walls, or floors), and vapor diffusion through materials that can occur slowly over time but saturate and damage materials nonetheless. The WBDG points out that solutions cover the gamut of design and construction activities, stating, “Preventive and remedial measures include rainwater-tight detail design; prevention of uncontrolled air movement; reduction of indoor air moisture content; reduction of water vapor diffusion into walls and roofs; selection of building materials with appropriate water transmission characteristics; and proper field workmanship quality control.” Listed all together, that may sound like a tall order, but in essence, it means that everyone involved in a building project has a role to play in managing moisture in buildings, starting with the design team.

In this course, we will look at three specific areas that are common to buildings, namely concrete foundations, wood-framed enclosures, and expansion joints. Each of these areas will be looked at for their general and specific issues related to moisture management, with some example solutions noted for each.