Building with stock” is currently the major topic of the architectural debate.

Successful examples can currently be seen in an exhibition in the German Architecture Museum, but the limits of what is feasible became apparent at a discussion event on Wednesday evening.

These were achieved, for example, with the renovation of the opera and theater in Cologne.

The stage building there is only about two-thirds the size of that in Frankfurt, but the construction tasks are quite comparable.

In Frankfurt, however, the renovation variant has already been rejected, even if an initiative is still fighting for the preservation of the double system on Willy-Brandt-Platz.

"damaged construction site"

Gunter Murr

Editor in the Rhein-Main-Zeitung.

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The timing is also comparable.

The first expert opinions were drawn up in Cologne in 2003, a citizens' initiative prevented the demolition of the theater, and renovation work began in 2012.

In 2016 he then took over a "damaged construction site", said Bernd Streitberger, Technical Manager of the stages and former head of construction in Cologne.

He has long since extended his contract, which originally ran until the planned completion in 2019, and all the schedules could not be met.

"The building services didn't work at all," reported Streitberger.

"The project hit a wall with that." This is partly due to the standards, which are now a big problem in Germany.

The call for tenders and reassignment of the building services planning alone took two years.

More than 100 percent cost increase

According to the current status, the Cologne stages are to be completed in March 2024. The budget of 253 million euros decided in 2011 has already been exceeded by 100 percent, and according to the latest forecasts it will ultimately be at least around 640 million euros.

The ancillary construction costs alone, i.e. above all expenses for planning and expert opinions, account for around 240 million euros.

"This pushes them to the limits of what is feasible," says Streitberger.

For Regula Lüscher, former Senate Building Director in Berlin, the Cologne example is not an isolated case.

"Every construction site hits a wall when it comes to building services." This is now overly complex.

If you overwhelm an existing building, you have to make an effort that is associated with a high consumption of resources.

In such cases, the preservation of existing buildings is no longer sustainable.