Dave

PETER HARRISON, Deputy Chairman, Stone Federation of Great Britain Technical Committee says, "I am frequently called as an "expert witness" in cases where stone installations have failed. The main cause of these failures is a lack of knowledge by the fitters."

This, in turn, is caused by lack of training and a failure to follow British Standards requirements, and Stone Federation of Great Britain guidelines. But we're now taking massive steps to change that by introducing the first NVQs for stone flooring installers.
Approximately 70 per cent of the domestic stone industry is made up of ceramic, porcelain and terrazzo fitters who have moved into the market thinking stone can be installed in the same way. And there is a very high chance that installers who are not trained in laying stone are going to end up with failures.
In the past a lot of stone was very hard marble or granite, which was relatively forgiving to movement stresses. Nowadays the trend is towards white limestone, in particular 600mm x 600mm x 10mm. These Johnny-come-lately fitters don't understand the characteristics of this thinner, more vulnerable stone. They don't understand how it performs, that it'll crack easily if the screed moves.
Because of the number of failures installers frequently say: "I'm not going to use stone - it doesn't work." Stone DOES work, and works very well. It gives a long-lasting, quality finish. But it must be fitted by trained installers, the design must be right, the stone used must be suitable for the application, movement joints must be used to compensate for surface movement, and uncoupling membranes are needed to prevent shear stresses being transferred from the substrate to the surface.
Very often the floor has cracked or debonded because installers have not fitted an uncoupling membrane or enough movement joints. The lack of movement joints often arises where the end-user customer doesn't want them because of the aesthetics of the installation. The installer should be alerting the customer to what will happen without them - but they're not doing, probably because they don't know themselves. And, of course, if laid properly, and sympathetically with the design, movement joints often improve the look of the finished floor, rather than detracting from it.
To overcome these problems the Stone Federation is working closely with the CITB who are currently funding a training officer for the stone industry. Our training group is hard at work drafting NVQs up to level two in stone flooring installation. We're aiming to see the first fixers starting to study for this new qualification by the end of the year.

Also the Stone Federation is publishing a new code of practice bringing together all the stone flooring elements of the different British Standards, including the use of uncoupling membranes, the maximum size of floors before intermediate movement joints should be incorporated, and the use of perimeter movement joints.
By setting up the industry's first NVQs I hope we can raise the profile of the Stone Federation so that more companies will join, and end-user customers will only want to use Federation members or companies who have staff with NVQ qualifications.
Also, installers, architects and specifiers should familiarise themselves with the new Code of Practice, and should warn customers of anything that falls outside the requirements. We don't want to stifle innovation, but we don't want untrained installers continuing to say they're not going to use stone again because it's such a bad product. If stone is laid properly, it will last for years - but it can only be laid properly by knowledgeable installers.
As a third step towards improving knowledge of how to guarantee the long-lasting integrity of stone floors, the Stone Federation has recently welcomed world market leader in tiling solutions, Schlüter-Systems, to its membership. Schlüter's Public Relations Manager Stewart Bint is now on the Training Group, and Technical Manager Ian Knifton sits on our Technical Committee.
Ian Knifton says: "Movement joints create independent tile fields, absorbing much of the surface movement. Without them the shear stress builds up between the surface and the screed, causing debonding and cracking. Therefore, stress-relieving joints are an essential part of any stone installation, and should be incorporated at the design stage. And an uncoupling membrane installed over the substrate, with the stone anchored to the top of it, will neutralise movement and cracks in the screed, preventing any stresses being transferred from the screed to the stone covering."
And Stewart Bint's PR and communications expertise is being offered as a free service to companies working on stone flooring projects. "While Schlüter primarily protects the long-term integrity of tiled installations through movement joints, uncoupling and waterproofing membranes, we feel it's important to help companies increase overall stone awareness amongst their target audiences.
"Judging by the number of cases where Schlüter is called in to trouble-shoot where stone installations have gone wrong, we're pleased to be able to play a part in educating stone flooring contractors, architects and specifiers, in the correct use of essential protection."
For more information contact:
Stewart Bint
T: 01530 813396
F: 01530 813376