Laying Paving Slabs

Laying paving slabs can be a lovely alternative to a typical patio or pathway in your backyard – however, before attempting this project, please keep in mind that paving slabs can be very heavy.

Please have a second person on hand to assist you, and do not strain yourself if you find the pieces are too heavy. If you are going to lift them yourself, make sure that your back is straight and that your legs take the weight instead of your back and midsection. Any slabs over 600x600mm should always, always be carried by two people. Also, be sure to wear heavy gloves and protective clothing to avoid irritation or burns on your skin.

Excavate the Designated Area

Plan out the area where you want to install the paving slabs, and make sure there is enough space for any water to drain off easily. Check your paving slab thickness, and consider the amount of sub base and bedding layer needed before you begin to excavate.

The sub base layer needs to be set up in order to take the brunt of the weight of the slabs and traffic. This will help to give your paved area durability and strength, and should be about 150mm deep.

It should usually be a mix of compacted, crushed rock, with little or no gaps where the bedding can seep in. Make sure it is even in thickness, and that your sub base essentially reflects how you want to see your paved surface.

Placing the Bedding

This layer will hold up and support your paving slabs, so it should be a mixture of dry cement and coarse grit sand – this should be laid down so that it allows the stones to lay flat and level. Building sand is far too soft for this layer, so use a 10:1 ratio of sand to cement, and you’ll find that the mix is firm.

The thickness of this layer should actually be determined by the thickness of your paving slabs, since the bedding needs to make up for the thickness of any of your thinner pieces of stone. Check how thick and thin your thickest and thinnest stone are, in order to make the calculations that determine the thickness of your bedding layer.

Laying the Paving Slabs

Spread out the bedding and make sure it’s compacted before laying down any of the slabs – however, you’ll have to check each slab’s thickness before it’s laid down, in order to level out the bedding mixture to the proper thickness. If you ripple the bedding mix with a trowel before placing each stone down, you’ll find that the stone is able to bed itself down much more firmly.

When you lay the stones, smaller stones can easily be lifted into place – however with the larger stones, you should carefully tip them into place from a solid surface.

Make sure you have a maul on hand to help align the stone in its position, tapping lightly on the corners as needed, to make it flush and secure against any adjacent stones. When it’s in place, walk on the stone to make sure it’s firmly in place and doesn’t move.

Joining and Pointing the Slabs

If you’re planning on dry jointing, make up a mixture of sand and cement and brush it in place – but only do this if the slabs are perfectly dry, and if there is no forecast for rain.

Use a soft brush to push the mixture into the joints, and pack it down with your trowel to make sure the joint is solid. The mortar mixture should be removed from the surface of any stones as soon as it gets on them, just to make sure there is no staining.

Pointing is a more time-consuming process, though it will last longer. The mortar should be mixed wet, and then trowelled into the joints between the paving slabs. If you can, use a larger trowel to hold the mixture and a smaller one to get it in the joints, which will actually help to minimize potential staining on the sides of the slabs. You’ll have to press the mixture down into the joint, and finish it off with a specialized jointing trowel.