Indian Sandstone continues to increase in popularity with British homeowners; however issues can occur before, during and after installation.
Here Marshalls’ stone expert, Rebecca Hall, discusses the technical performance of Indian Sandstone and how landscapers and installers can assess the quality of the stone they are installing in order to avoid issues further down the line.
Q. Why do you think Indian sandstone has become increasingly popular over recent years?
It’s because it can be an absolutely stunning product. People associate stone with a high-end luxury look and put a great deal of perceived value or prestige in having a natural stone patio.
Q. How many different types of sandstone are there available on the market? Are they all the same?
There are hundreds, if not thousands of different types of sandstone available in the UK and they all vary greatly in looks and performance. Many of the more commonly available varieties come from Rajasthan in India, or Shandong & Sichuan provinces in China.
Q. So is it easy to tell a good quality sandstone product from a bad one?
It isn’t always easy to tell just by looking. Many sandstones appear the same when displayed at a merchant or a brochure, but all sandstones are unique and often have widely differing properties. This can be why many similar looking sandstones afford very different performance when installed as paving. It can be hard to spot the tell-tale signs, but laboratory testing gives you a full picture of the technical quality of a stone.
Q. Technically speaking, what makes good sandstone from bad?
There is a raft of factors, but there are three key characteristics that must be considered when purchasing stone to be installed as paving in the UK; Water Absorbency, Flexural Strength and Frost Resistance.
Q. Why are these three things so important?
The absorbency of the stone is hugely important. A stone with high water absorbency will not only go green quickly, but may also be more susceptible to frost action which will degrade the stone.
Flexural Strength is also important factor. Stone with poor strength means that the product could be easily damaged in transit, during the installation process or simply by everyday use.
Finally, Frost Resistance is particularly important in the UK. A stone that loses strength when subjected to repeated frosts is far more likely to fail.
Q. Is there a British Standard covering these issues?
The BS7533 part 12 covers the technical performance of stone, for example, the British Standard for water absorbency is a maximum of 2.5%.
Q. So I’m assuming that all the stone on the market meets these British Standards?
You would be excused for thinking that’s the case, but it isn’t. We tested of a range of stones available on the market and only 50% of them met or exceeded the British Standard.
We found that half of the stones available on the market are not technically up to scratch and could cause a wide range of issues in the future.
Q. How can people ensure that the stone they’re installing is technically up to standard?
We advise choosing stone from a supplier that has tested their products and who can supply a relevant, in date test certificate or declaration of performance.
At Marshalls we have tested all our stone to be 100% sure that every single stone meets or exceeds the British Standard. This process of testing and ensuring that our stones are technically sound we have called The Stone Standard.