Architect Petr Janda of the Czech firm Brainwork created an architectural flow between the interiors and exteriors of The Rašín Embankment along the Vltava River in Prague. This unique riverfront area revitalisation project was a prize-winning project for Janda.

One of the challenges was to design six large ellipse-shaped windows with dimensions of 5500m in height and 5250mm in width, the largest of its kind in the world. The thickness of the window material needed to be 65mm to ensure minimised deflection and be able to fit in a slim line frame. Due to the enormous dimensions, the weight of the glass would require additional mullions to the tilting window frame. This would hinder a key design element of clarity, as the mullions would interfere with the views between the interior and exterior. Janda knew the solution: Acrylic

Petr Janda
Viewing window
January, 2020
Acrylic panel 58mm thick

Material in Details

Acrylic weighs half the weight compared to glass which is perfect for this project. In addition, it allowed a lighter framework and provided easier movement in the opening and closing of the window. Another added benefit of using acrylic over glass is the impact resistance and ease of repair and replacement when damages occur in this public space. On the other hand, glass beats acrylic on fire properties, which are vital in public space projects. Reynolds Polymer Technology is known for finding solutions and making the impossible possible, and they did find a working solution within the local requirements by developing flame-retardant acrylic.

Incredible Result

A proprietary polymer blend is utilized together with a chemical bonding process that uses multiple sheets to achieve the large structure scale without the need for additional mullions. Furthermore, this unique bonding process can be performed onsite, eradicating the limitations of transporting such a large piece of acrylic.