Choosing a stone for use in construction is not all about the colour and texture. The suitability, durability and the longevity of the stone for particular installations are also key factors.
In July 2013, the Construction Production Regulations made it mandatory for suppliers to provide key data and CE mark each product allowing users to make informed choices.
David Richardson is a Fellow of the Geological Society and past President of The Stone Federation of Great Britain and as a Natural Stone Consultant at FMDC he undertakes work on the suitability of geological materials for incorporation in building projects. David has worked with Natural Paving Products in developing our stone standard for aiding customer choice, see details of the standard on page 9.
David comments, "It is important for the end user to select the right material for their project, so buying from a supplier that provides compliant and tested products is very important. Consumers should also be wary that some suppliers fabricate test data to give the appearance that they comply with the Statutory Regulations. Also, buying from a source with good ethical and sustainable credentials helps minimise abuse and other unacceptable practices within the wider supply chain."
David Richardson Technical Committee Chairman of the Stone Federation and Natural Stone Consultant at the FMDC
The Natural Paving Stone Standard
Sandstones with a higher water absorption have the tendency to go green. To help prevent this we recommend sealing with one of the Pavetuf Sealants.
The flexural strength of a stone gives an indication of how strong the stone is. The flexural strength is measured in megapascals (MPa). The higher the number, the less chance it has of failing or delaminating once in-situ.
Frost can sometimes attack stone, but most are very resistant to it. We measure this by testing the flexural strength of stones after a cycle of freezing and thawing a batch of samples. We have graded our stones on the percentage difference between the maximum flexural strength test before freezing and the strength test after a repeated freezing. Stones that are not acceptable for the UK market do not appear in our collection.
Please note: The stone standards are applied to all Natural Paving sandstone flagstones and block paving.