GMP Architekten Transforms Hamburg’s Alsterschwimmhalle into a Spectacular Aquatic Oasis

The German firm GMP Architekten has renovated and expanded Alsterschwimmhalle, a swimming facility in Hamburg known for its unique double-curved concrete roof.

Having been compelled to shut down during the COVID-19 outbreak, Alsterschwimmhalle has been reimagined into a versatile leisure venue featuring a sauna and fitness center.

GMP Architekten‘s renovation projects emphasize that the central element of the structure is the heritage-protected roof, which consists of two towering hyperbolic paraboloid forms fashioned from prestressed concrete.

This distinctive architecture has led the facility to be nicknamed Schwimmoper, or Swimming Opera, as locals claim its graceful shapes bear a likeness to the Sydney Opera House designed by Jørn Utzon.

“In crafting the renovation strategy, we prioritized the preservation of the remarkable, cityscape-defining roof with its stunning shell shape,” expressed GMP Architekten’s lead designer Jörn Ortmann.

“Our goal was to maintain – or rather restore – its initial appearance,” he mentioned to Dezeen.

Alsterschwimmhalle was conceived by German architects Horst Niessen, Rolf Störmer, and Walter Neuhäusser along with engineer Jörg Schlaich for the purpose of serving as a competition facility, built between 1968 and 1974.

GMP Architekten refers to it as “an exemplary illustration of Hamburg’s post-war architecture”, with its roof recognized as a protected entity by Germany’s Office for the Preservation of Historic Monuments.

Nonetheless, it required a refurbishment due to the degradation of its amenities, which precipitated its closure in 2020.

“Alsterschwimmhalle remained operational until 2020 and was closed only due to the measures implemented to mitigate the coronavirus outbreak,” Ortmann clarified.

“Before the pandemic, the cost of maintaining the facility and its outdated technical systems had risen dramatically,” he added. “Structural issues and obsolete technology required a substantial renovation.”

“Furthermore, the limited variety of sports amenities adversely affected commercial feasibility, and there was no room for expansion within the structure.”

Alsterschwimmhalle’s roofing structure measures merely eight centimeters in thickness and achieves a height of 24 meters at its apex. It covers a floor area of 4,500 square meters with spans reaching as far as 96 meters, which the studio claims positions it among “the largest roofs of its type globally.”

The roof is supported by three columns, two of which are connected by a tie beam positioned beneath the primary pool. Restoring the building without interfering with these supports presented a significant challenge for the studio.

“One of the primary challenges concerning structural integrity was that segments of the old pool needed to be dismantled and reconstructed without altering or disturbing the existing roof during the renovation process,” Ortmann clarified.

“As a result, the tie beam that connects the foundations had to remain untouched and was under constant observation throughout the renovation.”

The roof has been rejuvenated with a modern membrane and insulating layers, crafted to resist deterioration caused by elevated chlorine levels, high humidity, and intensified temperatures.

As a component of the renovation, the principal glass facade and several exposed concrete areas have been refreshed, while the athletic facilities themselves experienced a more comprehensive redesign.

The 50-meter swimming pool and its 10-meter diving board remain largely the same; however, the bleacher seating has been substituted with a new diving pool.

All public areas have been redesigned to enhance accessibility, while the building systems have been optimized for better efficiency and environmental performance.

An addition to the northern side of the structure accommodates a second pool, which stretches 25 meters in length, as well as a training pool, changing areas, saunas, and fitness amenities.

According to GMP Architekten, the aim of the extension was to ensure it integrates seamlessly with the existing complex without imitating it.

“The required additions were thoughtfully incorporated into the overall structure out of respect for the existing heritage building,” remarked Ortmann.

“We did not aim to replicate the original design style of the structure during the renovation. The architectural expression of the new construction, both internally and externally, distinctly contrasts with the restored existing building without dominating it.”

Merging with the structure is a forecourt located in front of the principal entrance along with a new drive-in route for vehicles. A pedestrian-friendly access path from the east links with the city.

“By opening the site to the adjacent streets and parks, we sought to reinstate the connection between the Alsterschwimmhalle and the surrounding urban environment,” concluded Ortmann.

“The outdoor areas were made available to the public, featuring paths throughout the site. In some sections, these were redeveloped using, where feasible, reclaimed and refurbished materials from the original design.”

GMP was established in 1965 by Meinhard von Gerkan and Volkwin Marg. Alsterschwimmhalle was nominated in the eco-friendly renovation category of the Dezeen Awards for 2024.

Other restorations of significant landmarks highlighted on Dezeen include Feilden Clegg Bradley Studios’ “invisible repair” of the world’s first cast-iron building and Chatillon Architectes’ renovation of the Grand Palais in Paris.