wedi GmbH

Thermal bath in a listed building: safe and fast renovation thanks to wedi

Individual solution for Neptunbad in Cologne

The term spa is from the latin term "sanus per aquam", meaning "health by water", and is taken literally in the case of Neptunbad in North Rhine-Westphalia. The bath in the west of Cologne was built in 1912 by the Royal Prussian architect Johannes Baptist Kleefisch in Art Nouveau style and has been operating as a wellness and fitness facility since 2002. Two unusual sauna areas are particularly popular: the Asian sauna and bathing area and the listed, historic Art Nouveau sauna.

The protection of the listed building was a great challenge during the renovation of the wellness area. Two aspects had to be taken into account: the construction had to be able to withstand the long-term high humidity load without drilling into the listed vaulted ceiling of the historic building, which was not allowed. Because of such special requirements, Neptunbad called on the expertise of wedi, one of the leading manufacturers of waterproof shower and bathroom systems and suppliers of customer-specific customised modular constructions for wet areas.

The Neptunbad in Cologne Ehrenfeld is a popular thermal bath, which, in addition to its fitness area, impresses with its two extraordinary saunas , a variety of wellness and atmospheric relaxation areas as well as its sun terrace. The historical ambience in the steam bath and laconium provides a special flair – both Art Nouveau treasures have now been renovated. 

An experienced team convinced: wellness builder Peters from Bochum and wedi GmbH from Emsdetten completed the renovation together. With its modular system components, wedi creates brand new opportunities for designing individual, on-trend bathrooms and wet rooms.
Lightweight and at the same time enormously stable wedi modules allow for the realisation of almost anything from the floor to the ceiling and practically everything else in-between: free-standing or partially attached creative partitions, shower solutions, customised bathroom furniture or complete system solutions for spa and wellness areas for example.

The advantage of the prefabricated wedi elements is that they are made of extruded polystyrene hard foam with an integrated vapour barrier providing ideal protection for backgrounds and subsurfaces against moisture. Reliable and long-lasting, they fulfil requirements that are of the utmost importance in steam baths.

Safety – the most important topic during the renovation

"One of the challenges in the course of reconstruction was certainly the fact that no drilling was allowed into the listed vaulted ceiling." reports Daniel Kösters, application engineer at wedi. "The mounting of the suspended ceiling construction and the load removal of the utilities on it had to be done entirely over the wall surfaces, and so, we designed integrated support points into the wall elements."

This, of course, had enormous advantages on site. A simple plug-in connection was then used to connect the suspended ceiling structure quickly and safely. In addition to preparations for the connection of the ceiling, piping for hot water heating as well as ducts for the electrical installations were integrated into the wedi components during manufacturing.

"This way we achieve two very important goals in complex projects like this. On the one hand, the high degree of prefabrication saves us an enormous amount of time on the construction site, whilst on the other hand, we achieve the highest level of security by reducing interfaces of different trades. This is the advantage of using wedi." explains application engineer Daniel Kösters.

The most important basis for such a project is in the production and release drawings: every component for the wellness temple – from the bench to the footbath – was individually planned and developed. The different components were then individually manufactured at the Emsdetten plant. The main advantage of prefabricated wedi elements is that they are made of extruded polystyrene hard foam and are 100% waterproof. For use in particularly humid environments, they are additionally equipped with a vapour barrier to provide ideal protection against high humidity levels for many years – reliably and long-lasting. This makes such complex renovations as this one an absolutely safe thing.

You get a first impression of what will later become a steam bath or laconium in the factory, because this is where all the components are first assembled.

"The test set-up in our factory is indispensable for me and my colleagues," explains Daniel Kösters, "in this way, we ensure that all parts fit perfectly and we save a lot of time on site – after all, the customer wants to get the facility back up and running as quickly as possible. It is also important that we reduce risks by cutting back on interfaces between the individual trades."

The master of tiles, Wolfgang Peters and his colleague needed only four weeks for the assembly of the wedi elements including piping and sealing as well as the tiling. Neptunbad is shining again in a new splendor and visitors can once again take a steam bath in Art Nouveau style.

Optimum cooperation on the construction site

On the construction site, the installation was characterized by the close cooperation between the processor and the installer, with many work steps carried out hand-in-hand. "The wall elements with integrated ducts for the different segments were supplied to us by wedi. We then set up the prefabricated wall elements and the installer connected the pipes together." explains processor Wolfgang Peters. The benches were set up in a similar way: connection pipes and flush-mounted fittings had already been integrated and sealed into the substructures at the wedi factory. Once the carrier elements were assembled, the pipes were connected before the placing of seat elements.

Most of the required elements were prefabricated at the wedi plant in Emsdetten, delivered to Neptunbad in Cologne and directly installed. "I only had to build two columns to the ceiling for the steam outlet with steam box and storage pieces  from wedi building boards on site – this is the huge advantage of wedi products, they can be processed individually, super fast and 100% safe." explains master tiler Wolfgang Peters. In the columns, he also bonded special fixing plates to which the steam, condensate and air supply lines for the steam box could be attached.

Fundamental: adequate sealing

The expert used wedi 610 adhesive and sealant to securely bond and seal the joints of the individual elements. An epoxy resin adhesive was additionally applied over the joints into which the wedi Tools sealing tape was embedded, then coated with epoxy-resin tile adhesive and sprinkled with quartz sand, to ensure proper sealing in high humidity environment. The sealing guarantees safety and durability and is one of the most important steps in such renovations. As the dominant Art Nouveau style of the sauna was also to be carried over to the steam bath and laconium areas, all elements were covered with tiles from the company Golem - art and building ceramics. Thanks to the experience of all parties involved and the high degree of prefabrication of wedi elements, the entire Neptunbad renovation process could be implemented quickly and without any problems, with the result which builders and processors alike were very satisfied.

Release date

November 2022

Press contact

Laura Recker
wedi GmbH
Hollefeldstr. 51
48282 Emsdetten

Phone +49 2572 156-176
Fax +49 2572 156-133


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