SentryGlas® ionoplast interlayer – 11 years on and still going strong

Designed and built by Bellapart s.a.u. between May 2001 and June 2003, the atrium roof and façades of the Endesa Headquarters in Madrid, Spain, have recently undergone inspection and testing to check for any degradation in the glazing.


The 113 x 36 m (370,73 x 118,11 ft) roof of the Endesa HQ comprises an almost horizontal flat glass surface composed of 861 point-fixed laminated glass panes, with a total area of approximately 3,150 m<sup>2</sup> (32,000 sq ft).
The glass panels, which vary in shape and size all feature a three-layer construction comprising 8 mm (5/16 inch) heat-soaked fully-tempered SLS glass top and bottom plies, sandwiching a 2.28 mm (90 mil) SentryGlas<sup>®</sup> interlayer.
With total life cost playing an ever important role in just about every industry, it is becoming more and more important for engineers and architects to specify materials that can offer the greatest performance over the expected life of a structure.

Designed by Kohn Pedersen Fox Associates (KPF) and engineered and built by Bellapart s.a.u. between May 2001 and June 2003, the atrium roof and façades of the Endesa Headquarters in Madrid, Spain, have recently undergone inspection and testing to check for any degradation in the glazing.

The multiple glass panels – the first to use SentryGlas® ionoplast interlayer in Europe – were found to be in extremely good conditions. So good was the condition that the tester commented that they looked and performed remarkably similar to more recently fabricated glass laminated panels.

The 113 x 36 m (370.73 x 118.11 ft ft) roof of the Endesa HQ comprises an almost horizontal flat glass surface composed of 861 point-fixed laminated glass panes, with a total area of approximately 3,150 m2 (32,000 sq ft). The glass panels, which vary in shape and size depending on their location, all feature a three-layer construction, comprising 8 mm (5/16 inch) heat-soaked fully-tempered SLS glass top and bottom plies, sandwiching a 2.28 mm (90 mil) SentryGlas® interlayer fixed with four point fixations and a silicone sealing between the panels.

The testing and lamination quality check involved removing an 11-year-old glass pane from the roof and then subjecting it to a thorough visual inspection prior to performing a pummel test; both of which were performed by a Kuraray Glass Laminating Solutions Technical Manager.

The close-up visual inspection was carried out in good lighting conditions and involved a painstaking search for any delamination marks or any degradation in the perimeter of the glass panel and around the mounting holes. This inspection revealed no delamination marks around the perimeter of the glass pane nor round holes and the interlayer looked just as good at the glass edge.

The pummel test – a test used on a regular basis by laminators to evaluate adhesion – was then performed on an area adjacent to a glass vertex, as it is the area most exposed to moisture ingress and degradation. The test showed a level of adhesion similar to that exhibited by much more recently laminated glass; proving that SentryGlas® panels exposed to environmental conditions such as those found in Madrid (hot summers and cold winters) demonstrates very good structural behaviour, even after 11 years.


Learn more about the Endesa Headquarters project by downloading the case study: