Corrosion often becomes a serious problem when car parks are getting on in years. If no immediate action is taken, the entire structure may be in jeopardy. This was the case with this current project.

The “ABC Tower” office building in Cologne contains a parking garage with fifteen parking levels in split-level design. It quickly became clear to us that there was an acute need for action. It was not only the age of the building, but also the poor execution of work during the construction process as well as inadequate maintenance and repair work that were causing problems.  The floor and ceiling surfaces in particular were showing signs of a progressive corrosion process.

Particularly problematic were the load-bearing ceiling sections, which showed signs of corrosion due to the ingress of de-icing salt. This was evidently already affecting the structurally essential plates on the undersides of the slab elements. It was not possible to determine the exact degree of damage to these plates without dismantling them. Neither can a reliable prediction be made about the further course of the damage. In any event, the damage has a direct impact on the load-bearing capacity of the ceiling structure – so urgent action was called for.

The plan: take action – comprehensively and quickly

To date, no consideration has been given to complete dismantling and new construction, although there are certainly arguments in favor of this approach. The repair option currently being planned essentially involves dismantling and replacing the ceiling elements. In addition, the surrounding railings will be replaced, as these also do not meet the relevant standards. The primary steel structure will essentially be retained. With regard to the repair of the ceiling panels, we do not see any technically viable and permanently functional alternatives in the present case (Hoesch additive system), especially in view of the degree of damage to the panels, which cannot be determined with any certainty.

A detailed examination of the structure by the engineering firms Müller & Braun and Holzapfel, Rüdt & Partner confirmed our own suspicions and showed that de-icing salt had penetrated the concrete, where it had caused partial corrosion of the reinforcement and the slabs. The structure can only be remediated by replacing the entire ceiling structure because not only the concrete but also the trapezoidal sheets are damaged. This requires urgency – the specified measures need to be implemented rapidly in order to avoid more serious damage to the structure, to restore its stability and to avoid greater costs in the future.

The planning phase of the project has already started. The start of construction work on site is subject to obtaining the building permit. Construction is currently estimated to take 15 months.