On one of the most beautiful stretches of Germany’s Lake Constance, nestles wellness oasis Therme Lindau whose seemingly floating design took an expert team 16 months to fulfill the architect’s vision.

Therme Lindau, Germany

Challenges faced included permeability, movement and waterproofing to construct 20 pools and 12,000m2 of surrounding natural stone and mosaic tiles.

Therme Lindau, Germany

Installer/Applicator: Reiser GmbH in Bad Saulgau
Architect: 4a Architekten GmbH from Stuttgart

On one of the most beautiful stretches of Lake Constance, the new Therme Lindau invites you to swim and relax. Spacious indoor and outdoor areas with over 20 pools – from the plunge pool and the 50-meter swimming pool to the brine pool – offer the greatest variety. Themed saunas and restaurants top off the beautiful offering.

As grand as the design of the spa and the view, so were the challenges the tile setters faced. “As with any swimming pool, first and foremost everything revolves around impermeability,” explains master tiler Christoph Reiser of Reiser GmbH in Bad Saulgau. “Then there are the many special features and details: the brine pool with its aggressive water, the stainless-steel sports pool, the water bars, the 30 x 60 cm tiles as well as the many mosaic tiles. We laid some of them in organic shapes.“


Seemingly floating: If you look out over the large pool through the glass front, the water surface connects with Lake Constance. The effect is similar to that of an infinity pool. Before the elements come together in such a seemingly weightless way, the pool surround made of natural stone had to be precisely installed. “My employees measured it on site – and then had it manufactured so that the pieces interlocked like a puzzle,” Reiser continues.

The connection of the tile to the large stainless-steel basin came with its own challenges and ARDEX employees visited the construction site regularly. “We were there again and again with our specialists to discuss the requirements,” says Jochen Polonyi, Sales Representative of ARDEX Germany. “This allowed us to understand the situation and propose individual solutions in cooperation with our Technical Service and the research and development centre.“


The procedure they came up with was unique and perfect for the situation: The craftsmen first degreased the stainless-steel rim and bonded the sealing membrane with the heavy-duty sealing compound ARDEX S2-K PU. The adjacent screed edge was neatly filled with ARDEX A 46 stable exterior filler so that it was flush with the stainless-steel edge. Then the recesses were further sealed with epoxy resin and covered with sealing tape.

The brine pool is a special highlight of the spa – and at the same time another challenge for waterproofing with its minerals and salts. The tilers were able to work with the heavy-duty waterproofing ARDEX S2-K PU once again. “We are absolutely thrilled with the quality,” says master tiler Reiser. “Above all, not having to sand is a huge advantage. It saved us time and we didn’t have to dispose of any leftover sand.”

In the brine pool, as in all other wet areas, the epoxy adhesive ARDEX WA was used. It is particularly suitable for areas subject to high chemical or mechanical stresses, such as swimming pools and spas. The surge tanks were sealed with the flexible sealing slurry ARDEX S7 PLUS. The advantage: the consistency can be variably adjusted. This meant that the waterproofing could be sprayed by machine onto ceilings and walls in the surge water tanks.

In total, 12,000 square meters of tiles and mosaics had to be laid. And the delicate manual work takes time. ARDEX S8 FLOW was specifically developed to level and waterproof large areas fast and can be applied with a squeegee standing up. “My employees really want to work with ARDEX S8 FLOW and always ask for it,” says tile professional Reiser. “It’s just easy to work with, and it goes on faster.” To waterproof and level the substrate for the 30 x 60 cm tiles, ARDEX S8 FLOW was applied in two coats.

During the construction phase, there were always changes and additions. Like the bathhouse that was additionally built. “We fully trusted the architect’s vision. Any new idea he brought up, we made it happen,” says Reiser. All the enclosures around the sauna ovens were to be clad in porcelain stoneware tiles. “It was important that the tile adhesive was also heat-resistant.” That’s why ARDEX X 77 was used. The fibre reinforced MICROTEC flexible adhesive is ideal for bonding tiles made of stoneware and porcelain stoneware, concrete and natural stone slabs.

After 16 months of work with an average of 15 employees, Christoph Reiser is pleased with the result. “It was a great team effort on the construction site. Everyone did their part.” The spa has been open to visitors since the summer of 2021.