David Domoney reminds how to lay a natural stone paving patio or paved area, correctly.
5 August 2022
Natural stone paving like sandstone, limestone, and slate has a wonderful impact in the garden when used to create an area to relax and enjoy the splendour of your surroundings. Once you’ve chosen the perfect natural stone, usually colour and texture, for the size and style of your garden, use this guide on how to lay the natural stone paving to ensure perfect reesults.
All the right tools
Among your toolkit you’ll need; string line, pegs, spirit level, tape measure, square, marking paint, rake, shovel, wheelbarrow, trowel, wide paint brush, drill, mixing paddle, rubber mallet, broom, brush, bucket, sponge, and a jointing tool.
Make light work of it
To make the task easier you’ll need some more specialist equipment which can be hired from a tool hire store; a cement mixer, vibrating plate, either a stone cutting wet saw or an electric angle grinder, and a segmented diamond cutting blade.
Fixing materials
For fixing materials, you’ll need; MOT Type 1 Stone or General Sub-Base, sharp sand, cement, Priming Slurry, and Pointfix Jointing Compound, to complete the job.
The all important safety gear
As with any task like this, you’ll need the usual safety gear to keep you protected – safety footwear, gloves, ear and eye protection and a dust mask which must be grade FFP3.
Getting started
Whether you’re starting from scratch or want to replace an old patio, ensure the area is clear of any old paving and some of the sub soil and rubble.
Marking out the area
Mark out the patio area using a square, a length of timber, and some marking paint. Mark out the dimensions of the new patio using a tape measure. Create a full outline by joining the corners together with marking paint using the set square laid out flat. The length of timber is a handy additional tool to extend the set square, ensuring a consistently straight line.
Setting the falls
Next, bang a timber peg into a corner until it finishes level with the grass. Repeat this in the next corner. Using a spirit level tap the second peg down until the sprit level shows the fall is 1:60.
All the right levels
Bang a peg in the remaining corners. Keeping the string line tight, tap the peg down until the spirit level shows that the string is level along the front edge. Next you need to measure the depth from the string line to the soil using a tape measure and work out how much needs to be dug out to accommodate for the 150-160mm depth.
All about the base
Check if the base is firm enough by digging the heel of your boot in. If it doesn't sink in, you’re good to go, but if it does, dig a little bit more out.
40mm laying bed
Rather than adding all the sub-base at once, just add enough until it’s half the depth required. Rake it so it’s level, before compacting down with the vibrating plate. Poor compaction will lead to an unstable patio. Once done, top up the rest of the sub-base, rake again, check the depth and compact with the vibrating plate. The finished depth should be around 60mm, from the top of the sub-base to the string line – meaning there’s 40mm for the laying bed and 20mm left for the paving slabs.
Be aware of the DPC
If you are laying your patio next to your house, the finished height should be 150mm, or two full bricks, below the damp proof course (DPC) of your walls. This usually can be identified as a layer of plastic sheeting within the mortar towards the bottom of the wall.
Get mixing
Mix up the priming slurry and laying mortar so you are ready to start laying the natural stone pavers in place. The laying mortar is made up from sand and cement at a ratio of 5:1, to make a creamy consistency. Depending on the size and shape of your patio, you may need to do some additional cutting to suit the specific curvatures of your garden.
The Mortar Bed
Apply the mortar in the corner and spread it around using a float or trowel to create a full contact mortar bed. This is to ensure the paving slab comes in to full contact with the wet mortar bed, with no voids for air or moisture.
Just like glue
Before it’s laid, priming slurry needs to be applied to the back of each slab using a paintbrush or roller to create a strong bond between the laying bed and the back of the slab.
Dust can form on the back of the paving as part of the calibration process. Its essential that this dust is cleaned off by using a brush or rinsing using water to allow for the priming slurry to work effectively.
Then, lower the slab onto the bed and tap it down to create a bond.
All lining up
When laying the first slab, take your time because the rest of the paving is going to follow the falls and levels from this one. This is the time to check that the edges align with the string. After laying each slab, give it a quick clean with water and a brush to remove any debris. Cleaning and removing excess mortar from the joints now will save you lots of hassle later in the process.
Colour and care
The joy of natural stone like Pavestone’s Classic Sandstone is there are no two slabs the same. Bear in mind that if your project needs more than one pack of paving, it’s essential that you pick and lay paving from different packs to guarantee that the colours blend effectively across the whole of the patio to create a seamless mosaic of colour.
Pointing and finishing
The newly laid patio will need to be left until it is hard enough to be stood on before pointing and finishing. Pavestone’s Pointfix All Weather Jointing Compound comes as one bag of coloured sand and resin, and the other of sand and hardener.
Thoroughly mix
The most important thing to bear in mind is that an equal quantity is needed from each bag, and must be mixed thoroughly.
Make sure the joints are deep & wide enough
Double check that the depth of the joints is a minimum of 24mm, with a minimum width of 6mm. Give the paving a good sweep to remove any debris and tip the mixture onto the first area.
Key the Joints
Make sure the joints are deep & wide enough. Double check that the depth of the joints is a minimum of 24mm, with a minimum width of 6mm. Give the paving a good sweep to remove any debris and tip the mixture onto the first area.
Compaction
Compact the joints well. Spread the mixture over the paving using a brush or a trowel and press it into the joints using a brick jointer, sweeping off any excess as you go. Give it a second compact down to ensure the joint is full. Repeat this process by moving the Pointfix around the joints with a brush, compacting, then topping up and compacting again.
A quality finish
A 'top tip' is to sweep the rest of the excess at a diagonal angle along the joint rather than straight down because that will pull the product back out of the joints. When the patio is done, any product on the paving stones can be swept down for a clean finish. Then, the natural stones can be cleaned using a sponge to rid any Pointfix mixture from the surface.
Natural stone paving looks fantastic and can transform your garden from ordinary to exceptional with a job well done. However, landscaping does represents a sizable investment. Get it wrong and you will be not only be very disappointed but may also be faced with having to spend thousands of pounds, all over again, to rectify.
I have have joined Mark Brown, Pavestone's resident expert landscaper, to present you this article and video demonstrating how to lay natural sone patio paving tiles. Follow our simple instructions and you will have many years of enjoyment from your patio.
How To Lay Natural Stone Patio Paving
There are many more videos featured here for you to explore.
David Domoney, TV gardener, horticultural expert and Pavestone brand ambassador blogs monthly on the Pavestone website on all things landscaping related.
We look forward to seeing you back again next month.