How To Lay Paving Slabs
Laying paving slabs to create a patio, path or simply a paved area for your garden can be really practical and very low maintenance. There are lots of things to plan and consider before starting work on your new paved area, including tools and some material to use as a base for the paving. With any project, it can be a good idea to seek advice if you are unsure of any part of the work.
Working out how to lay paving stones and build a sub-base is fairly straightforward, you may need some help though as most of the paving and base materials are heavy, especially if you are going to be using large paving slabs, so get someone to give you a hand. The easiest place to build a paved area is on a flat, level piece of ground. If you are going to build paving near to a building, you will need to check you are not covering the damp proof course.
Materials and Equipment
Materials and equipment you will need are:
- your choice of paving slabs, hardcore or similar for the base
- sand or cement for filling the joints between the slabs
- a piece of off-cut wood to use when laying the slabs to protect them
Tools you may need include:
- tape measure/ruler
- builder's square
- builder's line for marking out the paving area
- wooden pegs for marking the shape to pave
- claw hammer
- spirit level
- lawn edging tool
- rubber mallet
- dustpan and brush
It will also be a good idea to have some safety equipment too, things like strong gloves, a dust mask, safety goggles and strong work boots are all sensible ideas to make the job safer.
Where to Start
The first job would be to plan where your new paved area is going; you can mark this area out with the builder's line and pegs. Once you have the area worked out, it must be checked for cables or pipes that could be under the ground. There is a gadget for testing for cables and pipes that you can hire, hopefully, any cables or pipework will be well buried and not cause any problems.
You will also need to allow a slight slope in one side of your paving, especially in the case of a patio otherwise you may end up with standing water and puddles. By allowing for a slight slope, this rainwater will naturally run off. Normally this slope will need to be 12 to 16 mm per metre of paving so it is very slight. This slope should be faced away from any buildings to allow the rainwater to run away easily and not indoors.
When you start to prepare to dig out the ground for your paved area, it is a good idea to lay out your paving to check all the measurements are right and this will give you a chance to mix up the packs of paving so that you don't get colour banding from using one pack at a time. It is a good idea to add a small amount to the measurements say 5 to 10cms to the size of the base, this gives you a really good solid foundation for your paving. You will need to dig out enough soil to lay a good sub-base, for example, enough to lay 100mm of the base material, followed by a thin layer of sand or ballast material. Then you would use a 50mm layer of mortar, followed by the slab which is 65mm.
Using Wooden Pegs
You can use the wooden pegs to check and mark the correct level of the dugout base and any slope to allow for the rainwater runoff. Then use a long piece of wood and a spirit level to check they are all level. You can then add your hardcore base, it is possible to hire a machine to compact this easily for you. Keep adding more base material until you have enough compacted to reach the tops of your marker pegs. The next layer is of sharp sand to work as a binding coat. At this point you can remove the corner pegs and lines, the other pegs can remain in situ and be covered over.
Laying the Paving Slabs
Now you can start to lay your paving slabs, you will be laying them into a mortar layer. Mortar goes "off" ie sets hard in around two hours, so only mix small amounts that you can use in that time. You can either mix the mortar by hand or with a cement mixer for larger projects. So then start in one corner, lay enough mortar for the first slab - you can moisten the back of the slab with water as this helps you position the slab easily and it will set well. Using the spare piece of wood and the rubber hammer, tap your slab into position. You will need to be fairly gentle so as not to break the slab, and fill any gaps under the edges as you go using the trowel to straighten the edges. After this, you can go ahead and lay the rest of your slabs in exactly the same way. You can use wooden pegs to keep the gaps in between each slab the same. Keep using the spirit level to ensure your slabs are good and level as you work. If you need to cut slabs, it is best to hire an angle grinder to make this easier.
Once all your slabs are laid, the mortar will need around 48 hours to dry, if it looks like it may rain you will need to cover the area with a tarpaulin to keep it dry.
Once everything is dry, you can finish off by doing the joints between the slabs. If you have chosen to have small gaps in between the slabs, you can simply brush kiln dried sand into the gaps and then sweep the slabs to remove loose sand. If your gaps are larger you can use either a dry sand and cement mix or a wet mortar mixture. With the dry mixture you simply brush it into the gaps with a brush and as it absorbs moisture it will set firmly. With wet mortar, you would need to work it into the gaps more carefully and smooth it over once the gaps are full, make sure you clean the spare cement away as you go.