It can be hard to keep up with all the standards for building products, especially as they frequently change. In this column, Barry Hunt throws some light on the standards, identifying those you need and those you don’t. This time he looks at BS EN 1469 Slabs for Cladding.

This standard deals with the performance requirements of natural stone to be used for cladding and ceiling finishes. The design and installation of cladding is dealt with by other standards, notably BS 8298 that has been discussed previously in this column.

BS EN 1469 must be considered one of the most important standards presently available, as the failure of any stone cladding panel may have grave consequences.

The fall of a small, fist sized piece of stone from height has the potential to kill, so the need to conform to this standard cannot be over stated.

I should overlook the usual gripes about value for money because there should be no price on safety. Nevertheless, at £140 for a 31 page document, nine pages of which are the cover, index, and other standard text, we again have the usual exceptionally poor value for money now expected from British Standards.

Personally, I believe that any document that is involved in the possible prevention of accidents should be given away freely to encourage good practice and an informed public. 

The standard is reasonably informative, with easy to understand tolerances and notes on finishes initially provided. The need for the denomination and petrographic name are noted. The standard then takes the reader through the selection process – and was the first published standard to do this, although this procedure has now been repeated in many later standards. It is the most important part of the standard as it should set the visual boundaries that are often strongly linked to performance variation.

The range in visual properties should be reflected by the testing and therefore the declared performance values. Ideally, the test samples should be photographed so that confirmation can be provided that the test regime has taken into account the true natural variation.

The usual tests that may or may not need to be carried out are then introduced. Only flexural strength and the density and porosity testing are actually required, while frost testing or the load at a dowel hole depend on design and location.

As with so many of these standards, it is not clear who makes the decision about which other tests might be required, and there are no guidance criteria for anyone attempting to make such decisions. For example, who decides whether frost testing is necessary for a cladding to be used in the middle of London? All sorts of people run for cover at this point. The decision should be made by the person with design responsibility, but when they ask for results that are not available they could have to wait six months for the testing to be completed.

The remainder of the standard is taken up with the frequency of testing, including the requirements for factory production quality control, presentation of the test data and the way the packaging should be marked. These requirements are now standard for stone products and this information is repeated in all other natural stone standards that deal with requirements. They remain a persistent bugbear as they do not adequately tackle the problems of natural variation and the quirks of geology, so they cannot prevent a range of potential problems from arising. 

It is disappointing (but certainly not unexpected) that European politics has likely prevented the inclusion of meaningful minimum requirements for the performance of natural stone materials for use as cladding. An opportunity to ensure a minimum level of safety has been missed. Neither is it likely to form a part of future revisions. 

BS EN 1469 could have been a great standard, but it has fallen at the last hurdle and consigned itself to mediocrity. 

References:

BS EN 1469:2004. Natural stone products – Slabs for cladding – Requirements. Published by the British Standards Institution, London, England. 

BS 8298: Code of practice for the Design and installation of natural stone cladding and lining. Parts 1 to 4 published in 2010. Published by the British Standards Institution, London, England.

Barry Hunt is a Chartered Geologist and Chartered Surveyor who has spent 20 years investigating issues relating to natural stone and other construction materials. He now runs IBIS, an independent geomaterials consultancy undertaking commissions worldwide to provide consultancy, inspection and testing advice. Tel: 020 8518 8646 www.ibis.uk.net