Paving blocks are bedded into a layer of sharp sand on top of compressed Type 1 sub-base stone. They aren’t fixed with mortar, so there must be a retaining edge or kerb to stop them spreading. These edging blocks are securely bedded on mortar.
Tools and materials
Spirit level, Builders tools, Timber offcut, Builders / plasterers float, Edging blocks, Rubber mallet, Concrete and mortar, Sharp sand, Fine kiln-dried sand, Angle grinder, Block paving, Vibrating plate compactor
Laying a retaining edge
Excavate a strip around all four edges of the sub-base and lay 100mm-thick concrete footings for the edging blocks. The footings should project 75mm to the outside of the edging blocks and no more than 25mm to the inside.
1. When the concrete is dry, lay the edging blocks on a bed of mortar. Use a builder’s line and spirit level to position the blocks and allow for the fall across their surface. Bed the blocks down firmly into the mortar with a rubber mallet.
2. Use a spirit level to keep checking that the blocks are level with the string line across their width.
3. To hold the edging blocks in place, build up the concrete against their outer edges to at least half the block height. Leave to harden for 3 days.
Sharp sand for bedding blocks
With the edgings in place you can cover the sub-base with sharp sand. This is levelled to the correct depth with a board supported at each end with carefully positioned timber offcuts.
1. Dampen the sharp sand slightly and spread it to a depth of about 65mm. Use the board to level the sand, pulling the excess towards you.
2. Compact the sand to 50mm using a vibrating plate compactor, then loosen the top 10–15mm with a rake.
3. Use a builder’s float to smooth the sand down around any drainage point.
Laying paving blocks
Paving blocks can be laid in all sorts of different patterns, but when you are using them to make a drive the joints must be staggered to ensure the surface is strong enough to take the weight of a car. The pattern here is totally random, but you could lay different-sized blocks (small, medium and large) in regular sequences. Dry-lay a few rows first to check your design will work, especially at the corners and edges. Try a few different patterns to see which you prefer. It’s a good idea to work from several packs of paving blocks at a time, mixing up the individual blocks, as colours may vary slightly from pack to pack.
1. Starting from one corner, lay the blocks on the compacted sand in the pattern of your choice. Butt the blocks tightly up against each other. Wear knee pads and kneel on a length of timber so that you spread your weight over several paving blocks.
2. If you have to pave around anything, such as a rodding point, loose-lay the blocks that will need to be cut to fit.
3. Use a straightedge to mark the cutting line in pencil on the blocks.
4. Place each block to be cut on a bed of sand to hold it firmly in place. Wearing protective clothing (see below), cut the blocks one by one using an angle grinder with a particle diamond disc.
The perfect result
The laid paving is finished by filling the joints with fine sand. Then the blocks are compacted down into the sand, bringing them level with the top of the retaining edge.
1. Once all the blocks are laid, fill in the gaps between them with fine kiln-dried sand, brushing it into the joints with a broom.
2. Press the paving blocks into the sand with the compactor. If they drop too low, or they won’t compact enough, take them up and adjust the sand bed. Brush more kiln-dried sand into the joints, if necessary.