Overview of Moisture-Related Damage inOne Group of Wisconsin Manufactured Homes

In July 1986, reports surfaced of widespread moisture damage in walls of manufactured single-family homes in Wisconsin. The homes were manufactured by a company that declared bankruptcy and was liquidated justbefore the reports ofmoisture damage surfaced. This paper presents information about the nature and extent of the damage and summarizes the results of a health study of residents of the homes and air quality measurements of the homes. Site visits and a home inspection program revealed decayin fewer than halfthe homes. Mostdecay was in the sheathing, with far less damage to the wall framing. A survey of homeowners and airtightness measurements further confirmed that the damage was primarily due to excessively high indoor humidities, which led to conden­ sation in the walls during winter: Thehomes were veryair­ tight, leading to verylowventilationratesduring winter. In­ sufficient ventilation, combined with a relatively large number of occupants, appeared to have led to highhumidify conditions; the authors found a direct relation­ ship between occupant density and the incidence of moisture problems. Other features, such as the type of heating system, were nor found to have a significant influence. Medical evaluation showed that the residents of these homes suffered more often from respiratory pro­ blems than residents of similar site-built homes included in the study. This appears to be related more to the high level of several pollutants in the homes than to the presence offungal spores. However; no single individual contaminant couldbe identified as responsible for the irri­ tanteffect.