Gherkin in a pickle

The 590ft Swiss Re Tower, which now dominates the City's skyline, may be in trouble.

Even though the building - known as "The Gherkin" - was built using the latest design and technology, cracks are beginning to appear on some of the giant glass panels wrapped around it.

Twenty-five of the £8,000 panels have had to be replaced and all of the others are being painstakingly inspected to see if the problem has spread throughout the building.

The reason for the cracks is as yet unclear but contractor Skanska is carrying out emergency checks on all floors of the 40-storey building.

The cracks may have occurred during installation but damage may also have happened during the manufacture and delivery of the glass.

The glazing comprises two layers with the cavity ventilated by air drawn from the offices.

A Skanska spokeswoman told Construction News magazine: "Damaged panels were recorded as part of our quality-control procedure.

"A safety check is carried out as a matter of course to ensure that the integrity of the panel is not compromised. No panels have cracked after installation."

Replacement of the damaged glass, which was found throughout the building, is under way and will take eight weeks.

It is not expected to interfere with the move into the building of insurance giant Swiss Re, which will begin in December.

However, the problem will not help Swiss Re find tenants for the upper 25 floors of the 180-metre building. The tower has now been officially renamed "30 St Mary Axe" but will always probably be known as The Gherkin.

Giles Barrie, editor of the magazine-Property Week, said: "The Swiss Re Tower is half empty because the market is awash with empty offices, most of which are available for cheaper rents.

"Many potential tenants claim the unusual shape of the building makes it unattractive for their requirements. Now we have a problem with the glazing.