Gaskets for sash windows -

Make Rooftop Living Possible

Trelleborg’s sealing profile operation developed giant seals for Hacksteiner-Metall’s massive top hung rooftop sash windows that are contributing to easing the lack of affordable living accommodation in Germany’s cities.

Hacksteiner-Metall in Faistenau, near Salzburg in Austria, specializes in processing and working with metal. The company offers bespoke solutions – including giant rooftop top-hung sash windows. Specially designed to be built into roof surfaces, these windows are enormous, with elements in a width of up to 6.5 meters and a height of up to 5 meters; the sash covering an area of over 30 square meters in total. To ensure that the window does not become a structural weak point, high-performance custom-made seals from Trelleborg are a vital part of the solution.

Christina Barczyk, Sales Manager for Trelleborg’s sealing profiles, says: “There is a shortage of affordable living space in larger German cities and this poses major challenges for planners, architects and politicians. In inner-city areas, for example, where additional space is most at a premium, new builds are often not built for space reasons. A solution is to extend existing loft spaces and a key quality for successful rooftop living is a high level of natural light. This can be achieved by installing large-scale roof windows.”

Photo: Hacksteiner-Metall

Seals for giant rooftop top-hung sash windows

Trelleborg’s seals make a significant contribution to the structural properties of the giant rooftop top hung windows manufactured by Hacksteiner-Metall. Three types of specially developed seals, a frame, center and sash gasket, are used between the window sash and the frame. The seals compensate for component tolerances and movements caused by wind, heat or other stresses, as well as guaranteeing leak-tightness.

Bernhard Haaß, Manager Design and Industrial Engineering for Trelleborg’s sealing profiles, says: “We faced special challenges when developing the seals. Creating mounting grooves for ‘soft’ seals as used on smaller systems was not an option, so we had to work with hard rubber materials that can be screwed or clamped in place. These are used in combination with soft sealing elements, which are able to compensate for tolerances and movements in the system and that are uniquely placed one inside the other.” 


The jumbo top hung windows have been successfully tested for resistance to driving rain, wind, air-tightness, heat and noise insulation by the Institut für Fenstertechnik – ift Rosenheim and will soon be installed in cities around Germany. 

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