Calibrated Sandstone Paving Explained


Originally when Indian Sandstone started to be imported into the UK in the late 1990’s to early 2000’s , the most common product was uncalibrated with a thickness of between 25-35mm but quite often reached 50mm in thickness. These products were designed to replicate Yorkstone Paving which has been historically available in the UK for centuries but at a fraction of the cost. Indian sandstone paving quickly took hold across the UK paving market, offering far better prices and a better quality product than concrete reproductions that made up the vast majority of the UK paving market at the time.

Over time the Indian sandstone producers started to offer a calibrated sandstone paving product that ensured a consistent 22mm thickness. This meant more products could be transported in one shipping container, reducing costs and at the same time making installation easier and quicker thus helping to reduce installation costs here in the UK as well. 

The calibration process consists of the Indian sandstone slabs being run through a machine with multiple diamond tipped saw blades set to the desired depth.  As the slabs run through the calibration machine these blades cut grooves into the underside of slabs which leaves a series of cut marks running the total length of the slab and results in a slab that is left with a consistent thickness.

Premium Calibrated Sandstone Paving

At Natural Stone and Timber we pride ourselves on offering our customers top quality products and our direct relationship with our Indian Suppliers and the solid trading relationship we have built up over the last two decades allows us to dictate what quality and production standards we require, allowing us to offer a superior product at a far better price than most of our competitors. 

All of the Indian Sandstone Paving slabs supplied by Natural Stone and Timber will have ribs cut across the entire underside of the slab ensuring an even thickness, with a tolerance of only + or – 2mm from the stated 22mm thickness. Unlike many other suppliers, we do not allow thinner slabs to pass through the calibration process untouched, as this can result in thickness tolerance great than the required 2mm which will result in uneven slab thickness and therefore a weaker product.

Image above shows a fully calibrated Indian Sandstone paving slabs supplied by NST.

There are many benefits to a correctly calibrated product, the cut marks on the back of the slabs from the calibration process gives an increased surface area, on the underside of the slab, helping to achieve a strong bond between the paving unit and the bedding mortar, especially when a cement based primer is used such as Pro-Prime from Instarmac

Calibrated Sandstone also offers quicker Installation, the uniform thickness of Calibrated Indian Sandstone means the installer does not need to adjust the bed height to suit each individual slab. The bed can be laid at a consistent thickness speeding up installation times.

Economy Sandstone Paving

When limitations dictate that a budget friendly option is needed to complete a project, a great option would be our Economy paving which has the same surface finish as our premium 22mm calibrated sandstone paving but it has been calibrated to just 18mm thickness. Due to it’s reduced thickness this product is only suitable for domestic patio and pathway applications but apart from this slight limitation, it still offers a good quality product with all the benefits you receive from our high manufacturing standards stated above.