SentryGlas® was the clear winner when it came to specifying glass interlayers for the iconic Fallingwater in Pennsylvania, USA.

Designed by Frank Lloyd Wright in the 1930s, Fallingwater became a sensation almost overnight. Featured on the cover of 'Time' magazine in 1938 it has since become a National Historic Landmark.

The house was constructed between 1936 and 1939 over a 9.1 m (30 ft) waterfall. The landmark stretches out over the waterfall giving the illusion of floating in air.

Its age defying aesthetics, both internally and externally, have recently been enhanced thanks to the use of SentryGlas® ionoplast interlayers deployed in recently installed replacement glazing.

Since its original construction in the 30s, the building has been the subject of numerous renovation projects, including a major effort in the 1980s where the entire house was conserved for water and UV damage.

However, the replacement glazing panels, which incorporated a PVB interlayer, were starting show their age, with clouding, water ingress and delamination.

The Western Pennsylvania Conservancy started to research alternative replacement panels and its investigations all pointed in one direction – laminated panels incorporating SentryGlas®.

Lynda S. Waggoner, Director of Fallingwater and Vice President of the Western Pennsylvania Conservancy and Scott W. Perkins, Director of Preservation said: "We wanted to get as close as we could to the original 6.4 mm (1/4 in) plate glass, but we had concerns regarding color and clarity; we definitely did not want any tinting or diffusion. This desire had to be countered with the need to protect the interior wood and textiles from further UV damage.

"We started our research in 2008 by undertaking comparisons between glass with films and glass with interlayers," Waggoner explains, "but we soon realized that films had a huge impact on the color and clarity

“It was soon clear to us that the best approach would be to use an interlayer, which also meant that the maintenance and housekeeping staff could treat the new panels as they would monolithic glass panels – without the worry of damaging any sensitive films with scratches or chemicals."

When it came down to the choice of interlayers, the performance of PVB in the earlier re-glazing exercise meant that an alternative was being sought and SentryGlas® soon became the clear winner thanks to outperforming PVB in all tests.