Expansion

The Adel­indis Therme in Bad Buchau, located on the shores of Lake Federsee, offers guests a wide range of thermal and sauna expe­ri­ences across appro­xi­m­ately 14,000 m². Eight pools with varying tempe­ra­tures, bubble loun­gers, massage jets, and other well­ness features invite visi­tors to relax and unwind. Toge­ther with nearby clinics and a spa hotel, the Therme forms part of the Federsee Health Centre. The high quality of its offe­rings has earned the faci­lity multiple awards.

To create addi­tional space for well­ness and guest comfort, the operator – Moor-Heilbad Buchau gGmbH – commis­sioned the cons­truc­tion of a spacious exten­sion. In addi­tion to a new thermal pool, the project added a barrier-free entrance area with views of the Federsee land­scape, modern cashier and chan­ging areas, rela­xa­tion zones, a bistro, and a rooftop terrace featuring a sauna, pool, and garden.

The instal­la­tion of appro­xi­m­ately 3,500 m² of floo­ring across the extension’s three levels was carried out by Reiser GmbH from Bad Saulgau. The plan­ning and execu­tion of the tech­ni­cally deman­ding surface and drai­nage systems were closely coor­di­nated with system part­ners Ardex and Gutjahr.

Waterproofing

As part of the recent expan­sion of the Adel­indis Therme, a new, high-quality entrance and cashier area was created—designed to meet both archi­tec­tural and func­tional demands. Large-format tiles with a natural stone look provide a premium appearance and create a warm, welco­ming atmo­sphere throug­hout the exten­sion. The water­pro­ofing and adhe­sives were supplied by ARDEX.

To ensure long-term water­tight perfor­mance, the substrate was first treated with a self-leve­ling water­pro­ofing layer (ARDEX S 8 FLOW). The tiles were then laid using flexible adhe­sives (ARDEX X 78 and ARDEX X 90) speci­fi­cally desi­gned for the safe instal­la­tion of large-format surfaces. A rapid-setting flexible grout (ARDEX G 9 S FLEX 2–15) was used to achieve clean, even joints ranging from 2 to 15 mm in width.

A standout archi­tec­tural feature is the roughly 30-meter-long, four-meter-high wall in the entrance area. Clad in timber elements and illu­mi­nated by natural light, it makes a striking visual impres­sion.

The chan­ging areas posed a parti­cular tech­nical chall­enge. Nume­rous cut-outs had to be made to accom­mo­date 30 to 40 cm-high base units, which serve as static foun­da­tions for the lockers. These required a reliable decou­pling solu­tion to prevent cracking in the screed. A high-perfor­mance bonded uncou­pling mat (IndorTec VA FLEXBONE-VA) by GUTJAHR, speci­ally desi­gned for large-format tile instal­la­tions, was used to absorb struc­tural move­ment from the substrate. In combi­na­tion with a compa­tible bonded water­pro­ofing system, this resulted in a tech­ni­cally sound solu­tion that met both aesthetic and func­tional requi­re­ments.

Rooftop Terrace

The rooftop terrace—featuring a sauna, pool, and roof garden—required parti­cu­larly well-engi­neered tech­nical solu­tions. A perfect oppor­tu­nity for GUTJAHR to demons­trate its full exte­rior exper­tise, both in terms of drai­nage and year-round safety for users. In the outdoor sauna area, a heated floo­ring system was installed to prevent ice forma­tion in winter and to ensure slip-resistant walk­ways at all times.

This was achieved using a warm-water under­floor heating system, with pipes embedded in appro­xi­m­ately 20 cm of water-permeable drai­nage mortar. Reliable drai­nage is ensured by a two-level system: surface water is chan­neled through slim slot drains (Aqua­Drain SR) and a flexible grating system (Aqua­Drain FLEX). Below that, a specia­lized drai­nage mat—developed speci­fi­cally for use under exte­rior tile cove­rings on drai­nage mortar—forms the second drai­nage layer. With its capil­lary passive design, the mat effec­tively prevents stan­ding water from rising back into the tile assembly—an essen­tial factor in avoi­ding frost damage and efflo­re­s­cence.

The raised instal­la­tion of the tile surface over the open drai­nage struc­ture creates gene­rous drai­nage chan­nels, allo­wing water to flow away quickly and safely. The ceramic surfaces in wood and natural stone aesthe­tics offer both visual variety and high func­tion­a­lity. Barrier-free tran­si­tions were imple­mented in compli­ance with regu­la­tions using drai­nage grates that safely divert water into the under­lying drai­nage system without causing back­flow.

The combi­na­tion of water-permeable cons­truc­tion, varied slope condi­tions, inte­grated under­floor heating, and the use of precast concrete elements presented a considerable tech­nical chall­enge. However, the selected system design meets all the requi­re­ments for dura­bi­lity, drai­nage perfor­mance, and frost resis­tance.

Conclusion

All work was completed on sche­dule and without time cons­traints. Throug­hout the entire project dura­tion, the cons­truc­tion process—despite complex tech­nical requirements—was effi­ci­ently coor­di­nated thanks to close colla­bo­ra­tion among the involved compa­nies.

The expanded Adel­indis Therme now stands as a modern well­ness faci­lity that combines tech­nical precision with archi­tec­tural quality. Carefully matched complete systems for water­pro­ofing, decou­pling, and drai­nage ensure durable, high-perfor­mance surfaces—visually under­stated, func­tion­ally impres­sive. Visi­tors enjoy a relaxed, feel-good atmo­sphere, while a thoughtfully engi­neered floor struc­ture behind the scenes guaran­tees safety, acces­si­bi­lity, and comfort.

The design draws on regional refe­rences and blends harmo­niously into the natural land­scape of the Federsee moor. This project combines forward-looking tech­no­logy with context-sensi­tive architecture—resulting in a faci­lity built to inspire and perform for years to come.

Swimming pool and more

The Ilirija Sport City Centre in Ljubljana (Športni Center Ilirija), inau­gu­rated in spring 2025, is a public sports and infra­struc­ture project purpo­sefully located in an urban context. The new complex replaces an aging outdoor pool dating back to 1929.

At the heart of the faci­lity is a 50-metre Olympic-stan­dard swim­ming pool. Surroun­ding it are multiple sports halls, a café, a museum, event spaces, and public open areas—all situated beneath a striking 12,000 m² canopy that defines the urban character of the site. The ambi­tious usage concept allows not only for regular sports opera­tions, but also for cultural and social events. The goal is long-term acti­va­tion and econo­mic­ally sustainable use—even beyond the tradi­tional context of sport.

The decision to place the faci­lity in the city centre and to recon­nect it with Tivoli Park has created new links for pede­strians and cyclists, rein­for­cing the inte­gra­tion of sport into ever­yday urban life. And it proved to be abso­lutely the right move.

The project was desi­gned by Lorenz Ateliers, with the pools deli­vered by Myrtha Pools.

History and society

The history of the Ilirija Sport City Centre dates back to the late 1920s, when Slove­nian archi­tect and sports pioneer Stanko Bloudek desi­gned the original Ilirija outdoor pool with a 25-metre pool. The entrance buil­ding from 1929 is now a listed historic struc­ture. It was carefully restored and inte­grated into the new concept—as a café, confe­rence area, and museum dedi­cated to Slovenia’s sporting heri­tage.

Shortly after Slovenia gained inde­pen­dence, the young capital Ljubljana decided to build a new Olympic swim­ming centre with supporting infra­struc­ture in the city centre. Choo­sing not to relo­cate the large-scale project to the outskirts, but instead to develop it further at the historic site, was both a bold urban plan­ning move and a forward-looking social state­ment. It honours sports as a public good while redu­cing the mobi­lity foot­print of such a faci­lity.

Another key aspect of the design was recon­nec­ting the site to neigh­bou­ring Tivoli Park by resto­ring the histo­ri­cally signi­fi­cant Latterman Avenue as a pede­strian and cycling route. Comple­men­ting this is the public plaza beneath the centre’s signa­ture curved roof—a connec­tive space that links the city centre to the park. It trans­forms the sports complex into an open, multi­func­tional place that brings toge­ther sport, culture, educa­tion, and ever­yday use.

Swimming at the centre

At the heart of the Ilirija Sport City Centre lies a state-of-the-art aquatic complex, built using Myrtha Pools’ inno­va­tive modular stain­less steel system. The hall features a 50-metre Olympic pool with a movable bulk­head, a 25-metre trai­ning pool, and the latest Myrtha Track Start blocks desi­gned for compe­ti­tion use.

Thanks to Myrtha’s advanced stain­less steel system, the pools meet the highest stan­dards for both trai­ning and inter­na­tional compe­ti­tion. The result: precision, dura­bi­lity, and ecolo­gical efficiency—all in a spec­tator-friendly envi­ron­ment.

The stain­less steel elements are corro­sion-resistant, low-main­ten­ance, and allow for the extre­mely precise fabri­ca­tion required for inter­na­tional compe­ti­tion. At the same time, the modular cons­truc­tion enables rapid instal­la­tion and flexible adapt­a­tion to future usage needs.

The faci­lity meets the stan­dards of the inter­na­tional swim­ming fede­ra­tion World Aqua­tics (form­erly FINA) and offers seating for around 1,500 spectators—an ideal setting for national and inter­na­tional events. At the same time, it remains open to school groups, clubs, recrea­tional users, and the broader sporting community—making it an inclu­sive infra­struc­ture for all.

Roof and energy

The swim­ming pool, sports halls, circu­la­tion areas, and func­tional zones of the Ilirija Sport City Centre are all housed beneath a swee­ping, large-scale roof. This steel struc­ture spans 54 metres and covers around 12,000 m², giving the buil­ding ensemble a strong visual iden­tity and defi­ning it as a cohe­sive archi­tec­tural volume within the urban land­scape.

But the roof does far more than shape the struc­ture visually: 4,000 m² of photo­vol­taic panels are installed on its surface, gene­ra­ting enough energy to cover the entire power demand of the centre. This rene­wable energy system is comple­mented by geothermal instal­la­tions and effi­cient heat pump technology—making Ilirija Sport City Centre one of the first zero-energy sports faci­li­ties in Europe.

Envi­ron­mental perfor­mance was also a top prio­rity in terms of sports infra­struc­ture: Myrtha Pools’ modular stain­less steel system gene­rates up to 50% fewer CO₂ emis­sions than conven­tional concrete basins during produc­tion. This tech­nical solu­tion fits seam­lessly into the project’s holi­stic sustaina­bi­lity approach.

City and heart

The Ilirija Sport City Centre is far more than a swim­ming faci­lity or a sports complex. It sees itself as a public space with multiple functions—open to elite and recrea­tional sports, educa­tion, culture, and social exch­ange. As an inte­gral part of urban life in Ljubljana, it brings toge­ther layers of use that are often spati­ally sepa­rated else­where.

The faci­lity is desi­gned for school sports as well as univer­sity programmes, club acti­vi­ties, and compe­ti­tive events. At the same time, it offers space for cultural happe­nings: even the swim­ming hall can be tempo­r­a­rily trans­formed into a concert or event venue—a move that makes sense not only in terms of opera­tional effi­ci­ency, but also from an urba­ni­stic perspec­tive.

The Ilirija Sport City Centre is a vibrant, inclu­sive space at the heart of the city. And that’s exactly where sports belongs.