Measurements behind Internal Insulation on Solid Masonry Walls with Different Orientations and Degrees of Repair in a Danish Multi-story Building

Internal insulation is used in many heritage buildings to ensure a better indoor environment and reduce energy use. This article describes measurement results from installing an internal insulation system in a Danish multi-story building. The internal insulation system consists of a fully glued vapour tight insulated plasterboard. To reduce the risk for wood decay and mould growth at the wooden beam ends in the floor construction, a 100-200 mm uninsulated gap was left above and below the floor construction. Measurements include the effect of orientation, degree of facade repair and influence of indoor moisture content. Results show in general acceptable hygrothermal conditions behind the insulation system. However, a gradual increase in relative humidity at sun-exposed walls was registered due to 'summer condensation'. The degree of surface repair also showed an influence on relative humidity levels during this period. At the uninsulated gap above the floor, a higher moisture content indoor resulted in a higher relative humidity, though without exceeding the threshold for mould growth. However, a large temperature range was registered. The influence of the uninsulated gap on reducing the risk of wood decay and mould growth at the beam ends could therefore not unambiguously be confirmed.