Moisture negatively impacts the structural integrity of houses. Research documenting this damage dates back many years but became more prevalent with the progressive tightening of residential houses that began in earnest during the energy crisis of the 1970s (Sherwood and TenWolde 1982). The existence of moisture problems in any home depends upon several factors, including the quantity and duration of condensation, the building materials in place, indoor and outdoor temperatures, and the ability of the home to expel excess moisture (NAHB 1987). Moisture damage includes wood decay, paint failure on finished surfaces, buckling of sheathing or siding, and the reduced effectiveness of insulation (Sherwood and TenWolde 1982). A Canadian field survey of 201 moisture-damaged houses (VanPoorten 1983) reported buckling and warping of siding, high moisture readings in sheathing, mold and mildew within the house, high moisture readings in wall cavities, severe window condensation, window frame damage, and mold and mildew as well as high moisture readings in attic spaces. The Canada Mortgage and Housing Corporation Builders’ Series (CMHC 1988) noted the following problems with regard to moisture in wall cavities: rotting of structural members, deterioration or staining of exterior sheathing, deterioration or staining of exterior siding, warping of wood siding, efflorescence or spalling of brick or stone, peeling of paint on exterior siding, corrosion of metal fasteners, mold and mildew on structural wall members and on exterior sheathing, and water staining on interior finishes. The report goes on to identify other problems relating to moisture such as condensation on walls, ceilings, windows, and other surfaces. In the mid-eighties, a study was conducted in Champaign, Illinois (Rose 1986). In part, the study attempted to look for any connections between observed moisture and its sources. Results showed a relationship between moisture damage and moisture sources and also that construction practices, not lifestyle, were mostly responsible for the moisture problems. In a separate study, Angell (1988) concluded that the indoor relative humidity levels of 46% - 61% found in a group of panelized homes in Minnesota resulted in problems that included condensation on most storm windows, mold growth on indoor window sashes, condensation staining on walls and ceilings, wet basement rim joists, and general siding moisture stains. Anderson and Sherwood warned homeowners about condensation problems in a bulletin prepared for the Department of Agriculture as early as 1974.
The full research study can be found here: