Field temperature and moisture loads from a building envelope as the basis for accelerated aging of barrier membranes

Abstract

Temperature and relative humidity (RH) data within the building envelope of a single-family home at the National Research Council of Canada’s Canadian Centre for Housing Technology were collected over five years. We report on the distribution, rate of change, and the limits of temperature and moisture variations for south-easting wall and south-facing wall and roof systems to better understand the in-situ environmental conditions to which building materials and components typical of homes in North America may be subjected. Over an average year, wall temperature varied from −25 °C to +45 °C, and temperature followed a bimodal distribution, with maxima at 0 °C to 5 °C and 15 °C to 20 °C. Each maximum represented about 1100 h of field exposure. Roof temperatures, which spanned a temperature range from −35 °C to 75 °C, did not show a Gaussian distribution but were characterized as being multi-modal. From values of temperature and RH, absolute moisture contents within the building envelope were found to range between 1 and 55 g/m3, with the most common values being 6–8 g/m3. The application of this information is discussed and related to the development of realistic accelerated aging conditions to obtain a more accurate durability assessment of building envelope materials used in Canadian dwellings.