Not all stone was created equal.
Indian sandstone has become increasingly popular in the UK in recent years as a domestic patio or driveway product. Due to its strength and versatility coupled with its natural beauty, Indian sandstone is often the chosen product with many homeowners to produce functional yet stylish spaces for family and social use.
Yet there are many hidden dangers with a significant proportion of the sandstones available on the UK market today. Many of the cheaper sandstones are soft, porous stones which are easier to process, making them cheaper, but not strong enough to withstand the harsh British climate.
At Marshalls, all our sandstone is covered by the Stone Standard quality mark which gives our customers complete assurance that all the sandstone we provide is fit for purpose.
Watch our mythbusting video on Indian sandstone by Geologist Rory Kendrick
What is the Marshalls Stone Standard?
The Marshalls Stone Standard mark gives our customers full assurances that all Marshalls sandstone exceeds the base technical levels outlined in the British Standard for design and installation, BS 7533-Part 12. All Marshalls stones are repeatedly tested by an independent UKAS accredited laboratory.
The Marshalls Stone Standard sets minimum base criteria to which all our sandstone performs. These attributes are the most important technical factors that must be considered before choosing a stone for your patio or driveway project:All sandstone sold by Marshalls
will have a maximum Water Absorption of 1.7%
This figure tells you how porous the stone is. Sandstone with a water absorption percentage higher than 1.7% could go green within a matter of months, become slippery and be more susceptible to frost deterioration.All sandstone sold by Marshalls
will have a flexural strength of no less than 12.9mpa
The Flexural Strength of a stone gives an indication of how strong the stone is. The higher the number, the less chance it has of failing or delaminating once in-situ.All sandstone sold by Marshalls will be frost resistant
If a stone loses strength or starts to fall apart when subjected to repeated frosts (an essential characteristic in the harsh British climate), then it isn’t fit for purpose. The Marshalls Standard is a reduction of no more than 10% on the flexural strength of the stone after 56 freeze/thaw cycles and a visual inspection rating of ‘0’.
Any sandstone paving that doesn’t meet ALL these criteria may not be fit for purpose and could fail. Ask your sandstone supplier for relevant and valid test certificates for all the sandstones you are considering using on a project. All Marshalls stone is CE marked and tested in accordance to BS EN 1341. Declarations of performance are available to download at www.marshalls.co.uk/dop
What can happen?
What can happen if you don’t install stone that complies with the Marshalls Stone Standard?
All the softer sandstones will start to go green very quickly unless given expensive and often temperamental sealing treatments which have to be reapplied every year. These stones also have poor compaction between the sedimentary layers which could lead to the bedding planes separating and your stone starting to split and crack. Worse still, if moisture exploits the gaps in your stone, ice crystals can form and the surface of your stone could pop and come away in sheets. All these issues could happen to your new patio installation in a matter of months if you choose an inappropriate stone.Download the PDF for more information