Getting ready to lay your patio
Ground preparation
Preparing the ground for paving depends upon site conditions and the intended use of the paved area. If your ground is firm you probably only need to remove the turf and topsoil to a depth to accommodate the 30-40mm sand bed plus the slab and mortar thicknesses.
If the subsoil is wet or spongy you need to dig out much deeper to put in a stabilising layer (approx. 100mm) of well compacted hardcore (often called MOT, scalping, crushed hardcore) before laying the sand bed, again allowing for 30-40mm of sand plus the slab and mortar thicknesses.
In reality, few areas are already level enough for immediate paving, so some areas need to be excavated whilst others need to be made up with compacted hardcore. The use of hardcore helps ensure adequate site drainage, which is a prerequisite for paved areas.
Natural Stone
We would recommend that you use a 25-35mm wet mortar bed on 30 to 40mm compacted sharp sand. (Please note that a hardcore foundation may be required according to your ground conditions).
Which way up?
There seems to be some confusion about the way you lay Natural stone, please see the diagram as detailed below:
Correct Way
Incorrect Way
Cutting
If your patio involves a lot of cutting we would advise that you hire a powered cutting tool with a diamond tipped blade (any hire shop will advise you of the machine and blade you will need if you advise them of what you are intending to
cut).
Please take care and also make sure that your hire shop issues you will full instructions and relevant safety equipment, including goggles.
Laying
You should use a wet mortar mix of 1 part cement to 5 parts of building/sharp sand. Ensure that you use the full mortar bed method as this will ensure that there will be no spotting on the sandstone. You may need to increase the level of the mortar bed depending on the random thickness of the slab.
Pointing
There are several methods and products in the market to help with the pointing of paving products. Air reacting jointing products that can be found in most Builders Merchants or Patio Centres, or why not use the old fashioned cement and mortar mix.
The joints should be pointed as soon as possible but not if rain or snow are forecast. As with all natural stone products, we recommend that paving is laid allowing for a minimum of 10-15mm joint. We recommend joints are pointed using a wet (but not sloppy) cement mortar mix to produce a more permanent waterproof finish. Do not leave the joints unpointed for more than a couple of days. You must not attempt to brush the mix across the surfaces of the slabs as any cement left on the slab will result in unsightly staining and will often mean a complete renewal of products.
Selection
We recommend that whenever laying natural stone you should mix your paving from 3 -4 different packs (where possible) as you lay your patio. This will allow the colours to blend and help to improve any shade variations that may occur between packs, giving your patio a more natural look.
Stone Plus UK cannot accept any responsibility for any mortar staining, cutting or problems during the laying of their sandstone and limestone.