A £57million dispute between contractor John Sisk & Son and Hong Kong-based luxury hotel chain Shangri-La over stone falling off the walls of the hotel rooms in The Shard, London, was settled out of court last month (September).

The two companies issued a joint statement saying they had reached an “amicable settlement”.

Problems with the stone fixing contributed to delays in completing the fit-out which delayed the opening of the hotel on floors 34 to 52 of The Shard.

Shangri-La’s claim against Fisk included £40.2million for putting right work that Fisk was in charge of in 2012 and 2013 up to August when it was replaced by Chorus.

Central to Shangri-La’s claim was the allegation that marble wall tiles in guestrooms had to be replaced because resin mesh backing on the underside of the tiles prevented them from sticking properly to the substrate used for the walls.

The high profile case has highlighted the problems that can be associated with fixing resin mesh-backed stone.

Lee O’Connor, Director of specialist stone contractor Grants of Shoreditch, was consulted on behalf of the Shangri-La hotel after the problem had arisen.

He told NSS: “When I started in this business you didn’t glue stuff to the wall.” The steel frame structure of The Shard with board walls inside made it a difficult installation because of the amount of movement to be expected. “I said the only way we would do it would be if it was mechanically fixed – the old way of doing it.” Grants fixed the stone in a few of the bathrooms to establish a standard to be achieved, said Lee.

Speaking generally, he complained about the now common practice of some suppliers, especially in the Far East, of putting mesh on all their stone to make it easier to process. He also complained that stone is being sawn 18mm thick rather than 20mm to get more slab from a block. But that could compromise fixings.

Peter Harrison of consultants Harrison Goldman was also involved. He said he spoke to the Chinese producers of the stone. “I asked them if they had a problem with the backing. They said: no, we fix it mechanically. BS8000 Section 11 says if there’s more than 25% mesh covering it should be mechanically fixed.”

Stone experts Bruno Miglio, David Richardson and Darren Anderson at Facades & Materials Design Consultants (FMDC) said there are many variables with mesh backing, starting with how well it is applied to the stone in the first place right through to the substrate the stone is attached to and the adhesive used. “We’re not saying don’t use it, but be careful how you use it.”

At the end of 2013 The Tile Association (TTA) issued a statement urging caution over the use of mesh-backed tiles and slabs. And Stone Federation published a guide this year called Natural Stone – Installation in Wet Rooms, Steam Rooms and Shower Enclosures. It says: “Resin mat backed stone must be treated with caution as it will not bond to polymer modified cement-based adhesives. There is also a risk that where a bond between the adhesive and the resin mesh backing is achieved, a loss of bond between the resin mesh and the stone is liable to occur in wet or damp conditions.”