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Stone Standard
At Marshalls, we are committed to supplying the highest quality materials to the UK market. Many of the cheaper Indian sandstones supplied in the UK are soft, porous sandstones, which are often not fit for purpose and could fail during installation or once installed.
To help save our customers from poor quality sandstone, we created the Marshalls Stone Standard, a list of guarantees we stand by that give you that give you complete confidence in the sandstone you select from us.
The Marshalls Stone Standard mark gives you assurance that all Marshalls sandstone products exceed the base technical levels outlined in the British Standard, BS 7533 Class 2.
What is the Marshalls Stone Standard?
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:
Stone Standard Exceeded
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
Water Absorption
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.
Flexural Strength
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.
Frost Resistance
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’.
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.
