Forty double-glazed panels on corner facade at Portcullis House to be replaced after 16 crack.
Glazing on the front of Portcullis House will have to be replaced following the discovery that a number of panes have cracked.

Up to 16 of the 2 × 1 m exterior glazing panels that are part of the building’s curved corner facade have starting cracking. It has been decided to replace 40 of the curved panes. Insiders put the cost at up to £250 000.

The faults were discovered towards the end of last year, and following an investigation, it has been decided to remove the panes and replace them with a thicker glass. It is not yet clear whether the problem stems from the system’s design or the installation.

Arup Facades Engineering, which designed the fenestration system, and joint-venture contractor Seele Alvis Fenestration, which carried out the installation, referred all enquiries about the scheme to the Parliamentary Works Directorate.

Andrew Makepeace, project director at the Parliamentary Works Directorate, said: “We are changing the glass on the upper floors of the building. We are changing the specification [for the glass] on advice from Arup after earlier ones cracked.” He added: “Liability for the problem has yet to be established.”

The affected glass is double-glazed and fitted with a bomb-blast film for security. The system comprises one thick pane joined to a thin pane and it is understood that the heavier glass was imposing an excessive load on the other pane.

Schal’s Portcullis House project manager Roy Davis said: “We didn’t realise the extent of the problem until late last year. The instances of cracking were too high, so we have changed the specification.”

The instances of cracking were too high, so we have changed the specification

Roy Davis, Project Manager, Schal

He added: “We have over 3500 panes in the building and have had less than 0.5% breakage.” Davis added that there was no suggestion of the panes dislodging from their frames and falling out. Replacement work is due to start next week and be finished by May.

The glazing problem has been revealed at the same time as concerns about excessive settlement in the structure.

A number of project insiders said the building was moving more than had been anticipated. The building was designed to allow for a degree of movement so it would be better able to withstand a bomb blast. Makepeace confirmed that the building was moving but insisted that it was not a major issue and that it was unconnected to the glazing problems.

“There have been some difficulties fitting stuff on site, but it’s part and parcel of a building like this. It’s part of the problem of doing so much prefabricated work off site,” he said.

Davis added: “Arup predicted how much the building would move during construction and, by and large, it has moved in accordance with its predictions. The movement only affects the courtyard area; there is no movement on the external facade.”

Glazing specialist Portal, which is working on the building’s atrium, has no involvement in the external glazing.