Rain resistance of precast concrete sandwich walls with façade details

There are problems with water intrusion into new external walls of prefabricated concrete sandwich panels in Sweden to a varying extent.

The aim of this study was to obtain documented knowledge and data on driving rain resistance, to provide a basis for improvements in concrete sandwich walls with façade details.

Inspection results showed that, in all buildings, vertical joints between the concrete elements were often significantly too narrow and, at the same time, adhesion loosening of soft mastic in these joints was common. In general, small openings of tubes for depressurisation, drainage and ventilation were often incorrectly placed or had a bad incline. Cracs in concrete panels are also a problem. Field measurements indicated no pressure equalization which is also confirmed by lab measurements.

Lab results for concrete sandwich walls indicated inward leakage at window-wall interfaces, through openings of tubes and in joint with pre-compressed sealing tape.

To our knowledge, the majority of solutions being used are probably not verified with regard to driving rain which in itself unnecessarily risky.