In the Czech river valley of the Berounka near Prague, Stempel & Tesař Architekti have created an extraordinary private residence. The elongated structure is primarily made of steel and glass, featuring oversized air-lux sliding windows. The entire volume juts out into the landscape like a pier.
Villa Sidonius embodies the purest form of view and overview. For good reason—the landscape along the Berounka River is characterized by the flora and fauna of various nature reserves. The town of Černošice, located on the southwestern outskirts of Prague, is also nestled in greenery. This environment inspired Stempel & Tesař to design this single-family home, resembling a pier stretching out into the landscape from a hillside.
The rectangular box of steel and glass is supported by massive reinforced concrete columns. One of the taller columns, consisting of two parallel slabs, provides access to the house via an elevator, which is reached underground through a tunnel from the garage at the base of the hillside. There's also guest accommodation here. The main living area is situated high within the pier-like structure, with a garden and a spacious terrace at the back. The concrete slabs of the support column frame a pool at this elevated level.
Contrasting Demands
The idea of using a glazed, single-story cube as a residence may not sound particularly spectacular today, not even if it is several meters high. However, the concept by Stempel & Tesař brought a number of challenges. With regard to the glazing and its opening, the investor insisted on sliding windows with a width of four meters—while maintaining a frameless appearance. The width of the glass elements had to be precisely synchronized with the steel beams of the main structure, and the building needed to be openable on both long sides. These requirements turned out to be technically almost impossible to meet for the sliding windows, as the required parameters were partially mutually exclusive. The unusually large sliding elements, measuring 4x3 meters, exceed what most modular frameless systems can offer.
Moreover, the location and structural design of the house also argued against such windows. Due to its elevated position, the north and east sides of the house, in particular, are exposed to weather conditions comparable to those faced by the 4th to 5th floors of a building. Conventional frameless sliding windows, with their passive brush or rubber seals, can only provide limited airtightness due to the lack of pressure. The required lift-slide system would also not align with a minimalist, frameless appearance for the doors. However, the consequences of insufficient tightness at this height are not only reduced protection against draughts and noise, but also the risk of wind-driven pressurized water intrusion.
Another obstacle was that the structure of steel beams undergoes significant deformation. Under variable loads, such as snow in winter or thermal expansion of the steel in summer, it behaves like an actual bridge. This can lead to deflections of up to 20 mm at the thresholds and lintels. However, modular minimalist systems can only absorb deflections of up to 5 mm at lintels and practically none at thresholds. Greater deformations can cause issues when sliding the windows, potentially leading to glass breakage. Airtightness is compromised in nearly all conventional systems if the base settles by just 2 mm.
Pneumatic Sealing as a Solution
The only facade system that could meet these requirements without functional or aesthetic compromises was the air-lux system. With its active pneumatic sealing, it withstands all weather conditions and is 100% impermeable against noise, wind, and water. The air-lux system can also accommodate much larger tolerances and building movements. Thanks to their membrane-like character, the air-lux air seals surrounding the frame adjust vertically and horizontally to such movements.
Meanwhile, opening the doors remains simple and comfortable. In this villa in Černošice, it is further facilitated by motorization. A total of four air-lux sliding windows were installed in the villa. Two of them are located on the north side facing the Berounka valley, where a glass railing has been installed to allow for an unobstructed view into the valley and the incoming daylight. This combination of light and view creates a unique living experience that blends modernity with closeness to nature.
The villa in Černošice is a strong example of the possibilities that the air-lux system offers architects, planners, and investors. The air-lux system is capable of accommodating 40 mm drops in the lintel and 20 mm in the plinth area. Additionally, sliding panels can be manufactured and installed with widths of up to eight meters and weights of up to 2,000 kg. These dimensions are achieved through an innovative construction that is both very robust and invisible, ensuring that even floor-to-ceiling sliding windows reveal only glass.
Architecture: Stempel & Tesar architekti, Prague
Distribution partner: Arnold 1990 s.r.o.
To learn more about villa Sidonius, visit air-lux's website here.
