Costly replacement of failed glazing on a new £41.5M atrium at London’s Guy’s and St Thomas’ hospital hit a key milestone this week
Contractor MJ Gleeson is replacing all 432 panels of glass in the atrium of the hospital’s Evelina children’s school, just seven years after the firm built it under a design and build contract.
It has now been forced into replacing the glazing - at its own cost - on the 87m long, 37m wide, 10m high glazed curved roof after the discovery of a defect in the spacers between the panes of glass.
Problems with glazing were first noticed in 2007, two years after the atrium was completed, according to Guy’s and St Thomas’ NHS Foundation Trust asset management director David Philliskirk.
“We began to notice misting in some of the window panes,” said Philliskirk. The problem stemmed from a chemical reaction between the spacers that separate the glazing panels and the silicone sealant that was used.
As a result the seal broke down and enabled water ingress, which caused the condensation.
After initial investigations, Philliskirk said “it transpired” that the 432, 1.5m2 double-glazed window panes that form the atrium’s roof were sealed with a thermoplastic spacer instead of a metal spacer as originally specified by principal designer, architect Hopkins.
Change not spotted
This change was not spotted by the client during construction.
“We didn’t know different spacers had been used,” said Philliskirk. “It wasn’t a detail we checked.”
MJ Gleeson project director Sean Quinn said it was a quite common spacer to choose and that there was “nothing underhand” about not using a metal spacer.
Lengthy discussions between the Trust and MJ Gleeson over the best solution to the problem concluded in 2009 with MJ Gleeson accepting responsibility for the design defect, which then said it would replace the glazing. By this stage around 100 panels were showing signs of misting.
The cost of replacing the glazing is being met by MJ Gleeson’s insurance policy.
The work is being carried out by glazing specialist Structura after original manufacturer, supplier and installer Klaus Fischer ceased trading in 2006. The new glazing is due to be fully installed by September.