Long term monitoring of repaired external wall assembly

Abstract

This study discusses on hygrothermal performance of external wall assembly based on long term observation on relative humidity and temperature in layered external wall assembly, when the resistance of water vapor in insulating material is higher than in the main framing of the studied building. In this case the location of the vapor barrier must be examined more closely. In 1974 completed building the facade of the building was made from concrete and bricks. The external wall assembly was repaired by replacing the thermal insulation and facade brickwork. The original brick-insulation-brick structure was unventilated like those used to be until mid-1980s. The repaired outer layer was constructed with a ventilation gap which satisfies the building codes in force. Old thermal insulation was replaced with aluminum foil backed polyurethane insulation. The aim of the study was to verify that the new structure was performing properly by measuring the circumstances inside the new external wall assembly. The performance of the repaired external wall was monitored by sensors installed in four depths and in five different locations in the building. Each of the sensors measured relative humidity and temperature for two years. The repaired external wall assembly was observed to be performing correctly. The aluminum foil backed polyurethane insulation functioned as planned as wall assembly’s thermal insulation and vapor barrier. Condensation of the indoor air into the structure was not detected during the measurement period. Neither was the outside air’s relative humidity condensed outside the vapor barrier during the measurement period. There was no observation of the condensation neither in the ventilation gap, nor in the fire resistant mineral wool layer during the measurement period, in any inside or outside circumstances.