|
|
 |
 |
Bodensee-Therme Constance: a joy for all the senses |
|
|
Bodensee-Therme Constance: a joy for all the senses
| Sopro Bauchemie products specified for major waterproofing and tiling contract
|
With the new Bodensee-Therme thermal baths, the German city of Constance now boasts a dazzling new attraction, set to draw tourists and local residents alike. The expansive new facility nestles into a gentle slope directly on the banks of the lake to which it owes its name ("Bodensee" being German for Lake Constance). The newly added state-of-the-art wellness oasis, with thermal baths and sauna suite, and the refurbishment scheme for the existing outdoor pool area involved extensive waterproofing and tiling works. For guaranteed top performance, designers and applicators opted for the use of products from Sopro Bauchemie GmbH's professional range.
|  |
The original outdoor swimming pool at the site, located on a headland east of Constance city centre, was inaugurated in 1890 and, following alterations, was rechristened the Jakob Leisure Baths in 1975. By the mid-1990s, however, it had become clear that the Jaköble, as the facility was fondly known to locals, no longer met contemporary bathing and wellness requirements. A feasibility study submitted to the local council in 1997 recommended a remodelling of the complex along with its renaming as the Bodensee-Therme Constance. One key criterion in the development brief for the new leisure, health and wellness centre called for the integration of the surrounding landscape and adjoining lake in the design concept.
Ships and water as architectural leitmotif
A pan-European architectural design competition held in 1998 was won by the Stuttgart-based practice 4a, whose three partners – Matthias Burkart, Alexander von Salmuth and Ernst Ulrich Tillmanns – backed by a 30-strong team of employees and trainees, are involved in the development, design and supervision of wide-ranging projects, both in Germany and abroad. Today, much of 4a's architecture centres on an exploration of the emotional impact of spaces. Taking "ships and water" as its central theme, 4a's competition entry for the Bodensee-Therme focused on a direct engagement with the adjoining lake, while at the same time developing magnificent sweeping vistas of the Alpine backdrop for their incorporation in the building concept. This aim was achieved through a subtle exploitation of the site topography. The building features two distinct wings, which seem poised to embrace the entire lakeside waterworld in a pincer movement. Caught within these two arms, the indoor pool area backs onto the service and changing room facilities, which are partly sunk into the ground, and is fronted by a 78 m wide, almost 10 m high glass facade that opens onto the watery expanse of Lake Constance and, on clear days, affords views of the Alpine foothill peaks. In a bold gesture, the western block, housing sauna suite and restaurant, juts out towards the lake like a ship's bow. The white railings and floorboards of the panorama sun deck on the upper storey of the timber-clad volume are a further nod towards the nautical aesthetic.
|  |  |
Spanning between the two blocks, the gigantic glass front provides a visual portal linking the pool hall interior with the surrounding landscape – including outdoor thermal pool, sunbathing lawn and the vast waters of Lake Constance, with its ever-shifting moods of light and weather. Viewed through the separating screen, the artificial waterworld and lake almost seem to merge. Those seeking a warm and cosy environment in the open air can linger in the 400 m² outdoor thermal pool, while a dip in the lake, reached via a walkway, is likely to prove a somewhat more invigorating experience. The distinctive quality of the light flooding the pool hall softly blurs the separation of inside from outside. Even the scheme's artwork, which, far from standing aloof, forms an integral part of building, picks up the theme of water and its physical experience. The spectacular glass facade was developed by Swabian artist Willi Siber in close collaboration with the architect team. The feeling of floating, balancing and weightlessness conjured up by the delicate, bubble-shaped drawings, is complemented by written concepts such as Warmth, Senses and Emotion, displayed in large letters on the glass front. Hovering above this like a sail, the deeply overhanging trapezoidal roof, projecting slightly upwards at the edges, lends the building its characteristic lightness.
Painstaking refurbishment and waterproofing of outdoor pools
Alongside the new-build component – thermal baths facilities plus sauna/restaurant block – the Bodensee-Therme scheme retained the existing outdoor pools of the old Jaköble. Yet, both the 50 m pool and the non-swimmers' pool required a full strip-out prior to refurbishment. In response to the ground conditions entailed by its location directly by the lake, the 50 m pool had originally been provided with a comprehensive grid of movement joints. In the course of the refurbishment, each of these joints was cut open to allow structural connection of the individual slabs by means of continuity reinforcement, thereby producing a monolithic pool structure suitable for waterproofing. The existing movement joints in the non-swimmers' pool, on the other hand, were completely retained. Here, a special solution already successfully implemented on previous schemes was adopted. This involved incorporation, at the joint locations, of double-ply sealing tape, which was bonded and overcoated with Sopro PU-FD surface sealant, a two-component liquid polyurethane resin.
The edges of both pools were carefully profiled – using Sopro AMT 468 levelling mortar with trass, applied to a bonding layer – to allow efficient tilelaying using the thin-bed, in preference to the commonly used thick-bed, method. Sopro's No.1 tile adhesive, which served as the bonding layer, was combed on and allowed to set prior to application of the levelling mortar. Sopro AMT 468 was also used to render the pool walls. A rapid-set screed incorporating Sopro Rapidur® B5 binder was used to make up the levels of the existing floor surfaces in the outdoor pools.
| |
|
Waterproof membrane
Only when the extensive preliminary works had been completed were the outdoor pools ready for treatment with Sopro DSF 423, a flexible, two-component, cementitious sealing slurry, which boasts a proven track record as a crack-bridging waterproof membrane. Its particular merits include straightforward application, even to complex substrate geometries, and first-rate adhesion. The water-vapour-permeable material is suitable for roller, trowel, brush and spray application. Sopro DSF 423 has been awarded both a general building control test certificate (abP) for liquid waterproofing products applied in conjunction with tiling and a test certificate to the relevant ZDB (Federation of the German Construction Industry) data sheet.
The tile coverings were then installed in the outdoor pools using the time-tested Sopro's No.1. The highly flexible cementitious tile adhesive excels above all by its high, C2-rated tensile adhesion strengths (> 1.0 N/mm²), high sag resistance due to fibre reinforcement and S1-rated deformability (> 2.5 mm). Sopro VF 413, a highly flexible thin- and floating-bed adhesive, was used to lay the ceramic tiling on the pool floors.
The joints in the coverings were finished using Sopro TFs, a high-strength, rapid-set, trass-bearing, cementitious tile grout suitable for extra-heavy-duty applications.
|  |
Intriguing new-build component
The newly added thermal baths facilities include a 300 m² indoor pool, a 400 m² outdoor pool and children's adventure areas. In addition to a traditional sauna, the sauna suite features a "löyly" steam sauna, a sanarium and a steam baths, supplemented by a (8°C) plunge pool, a (37°C) relaxation pool plus associated showers and changing rooms. Given the high humidity levels prevailing in all these areas, various waterproof membranes had to be installed prior to laying the ceramic floor coverings. A continuous waterproof barrier was particularly crucial for all pool decks, showers and changing rooms as well as for the children's pool in the thermal area and the plunge pool in the sauna block. With the remaining pools, the membrane was carried over the pool edge and down the pool wall, where it was tucked into a raglet. This additional waterproofing provision was particularly important for both the indoor and outdoor thermal pools, where the upper pool structure was too narrow in places to meet normal waterproof concrete requirements.
Good waterproofing and tiling practice
All waterproofing works to the new-build component were carried out using Sopro DSF 523, a flexible, one-component, cementitious sealing slurry used to produce crack-bridging waterproof membranes. Like the above-described Sopro DSF 423, this product also excels by its straightforward application, even to complex substrate geometries, and exceptionally high bond strength. Sopro DSF 523 has similarly been awarded both a general building control test certificate (abP) and a test certificate to the relevant ZDB data sheet.
Stoneware mosaic, held together by a paper facing, was used in practically all the pools to enhance the design. It was suitably fixed using Sopro's No.1 flexible tile adhesive modified by 10% Sopro FD 447 flexibilizing dispersion. A variant of the same product – Sopro's No.1 white flexible tile adhesive (likewise with 10% Sopro FD 447) – was used for the large areas of glass mosaic installed in the sauna and children's areas. The fully vitrified stoneware tiling to the poolside areas was laid using Sopro VF 413, a highly flexible, cementitious thin- and floating-bed adhesive meeting C2 E requirements to DIN EN 12004 and S1 requirements to DIN 12002. This product is particularly suitable for the efficient laying of ceramic tiles with full rear-face wetting using the floating method.
|  |
Here too, all joints in the coverings (including the mosaic) were finished with Sopro TFs Titan tile grout. Prime features of the high-strength, rapid-set, trass-bearing, Mikrodur® microcement-based material, which accommodates 2-8 mm joint widths, include its high mechanical and abrasion resistance. The product is therefore ideal for high-spec tile fixing and grouting applications and, particularly on swimming pool contracts, offers a truly viable alternative to reaction resin mortars. The tiling and waterproofing works were expertly performed by the Immendingen-based company Fliesen Graf GmbH. Formed in 1961, the specialist contractor, currently with a team of 18 skilled operatives, has earned itself an impeccable reputation, among other things, through the reliable and punctual execution of numerous major contracts, both in Germany and abroad.
| Featured Sopro products:
| Signboard
| | Client: | BGK-Bädergesellschaft Konstanz mbH
| | Architects: | 4a Architekten GmbH, Stuttgart
soe Stinner & Von der Oelsnitz Architektenges. MbH, Stockach
| | Engineer: | Kurz und Fischer GmbH, Consulting Engineers, Winnenden
| | Key figures: | Waterproofed and tiled area: 8,000 m²
Cost of refurbishment scheme: approx. € 25 m
| | Completion: | July 2007
| | Waterproofing and tiling contractor: | Fliesen Graf GmbH, Immendingen
|
|
|
|
 |
|
