Design errors and performance defects as causes of the risk for a collapse of the ceiling of the concert hall

The issue presented concerns the proper assessment of a ceiling underneath a modernised concert hall in a historic building as a case study. The reason for a reconstruction was to replace a wood block floor with stone slab floor made of marble. Shortly after the construction works, cracks which appeared, made the floor unsuitable for further use. In order to determine the cause of the damage, a detailed analysis of a state of the construction was performed within the technical diagnostics. The first element that was inspected was the way the cracks were distributed. This layout was typical for overloading of ceiling. It was assumed that the thickness of the concrete overlay of the Ackerman floor was 9 cm. In order to verify the actual layout of the floor layers, five different opencast works were taken from the top level of the floor cavity blocks. The actual layout of the uncovered parts differed from both the assumptions that were made and the new design. The arrangement of the floor layers that differed from the design documents, caused the overloading of the supporting structure of the Ackerman floor. Additionally, an incorrect design assumption has overlapped.