Strong solar radiation has probably led to cracks in the masonry of a stairwell in an apartment building in Düsseldorf.
The house had been temporarily evacuated, the fire department reported.
Residents noticed the cracks and called the fire department.
According to the structural engineer, the cause of the damage was that the steel girders in the masonry, which "due to the age of the house were partly exposed", had expanded due to the strong sunlight.
The fire brigade found that glass blocks had burst on the back of the house in the stairwell area.
Due to the expansion in the masonry, the three by three meter fields with the glass blocks were pushed apart.
Since the basic structure of the walls had proven to be stable according to the test and the apartments were not affected, all residents were able to return.
The courtyard has been cordoned off.
svs/dpa