A pressure washer is really the only option for shifting the stubborn grime that can build up on paving, patios, driveways and other outdoor surfaces. Similar to washing a car, the best way to clean your patio is to start by blasting off major dirt with a high pressure trigger lance and then wash using a lower pressure setting and water mixed with detergent.
Many pressure washers come with a dedicated patio cleaner attachment which can make the machine easier to manoeuvre across a large surface, ensuring an even, thorough clean throughout. A lance with rotary jet capability – that spins the water jet as it comes out – can also be very useful in providing an extra bit of power to shift every last bit of dirt.
Jointing is the final step in completing your patio. It's the process of filling the gaps between the paving slabs to provide a firm, level surface.
Depending on the size of the joints between the slabs, different techniques are used to ensure a hard-wearing finish. We'll show you how to joint three different jointing widths:
Begin jointing once the mortar is set underneath your paving slabs.
Cement can be coloured with a special cement colouring agent to complement the finish of your paving slabs. The colouring is added to a dry jointing mix, following the instructions on the packaging. Take care to use the same dosage if mixing more than one batch, to keep a consistent colour.
Using a soft brush, sweep kiln-dried sand into the joints between the slabs.
Finish off by sweeping the surface of the whole patio to ensure that it's free of loose sand.
Medium-size joints are best finished using a dry mixture of sand and cement. The addition of cement leads to a firmer finish and the mixture will set as moisture in the ground is absorbed over the first few days.
Mix one-part kiln-dried sand with one part cement in a clean bucket.
Gently sprinkle the mortar mixture along the joints. Brush in using a soft brush.
As you work, brush away any excess mixture from the surface of the slabs to prevent staining from the cement.
Compress the joints using a jointing tool and keep adding the mix until full.
For larger joints, use a wet mortar mixture.
Mix four parts building sand and one part cement in a bucket, adding clean water until you achieve a slightly moist, smooth, damp consistency. Add the water slowly to the mix to help avoid creating a wet or sloppy mortar that runs easily off a trowel or jointing tool.
Work the mortar into the joints using a trowel. Push the mix down firmly into the joints with a jointing tool, and repeat this process until the joints are full, compacting and smoothing as you go.
With the site dug to the correct depth and pegs in place, it’s time to start laying the patio’s sub-base.
Using a wheelbarrow, tip in enough hardcore to fill your sub-base to just above the top of the wooden pegs.
Compact the hardcore with a plate compactor.
Check that the surface is level with the top of the marker pegs, and add more hardcore and compact again if necessary to reach this level.
Cover the surface with a thin (10mm) layer of sharp sand or all-in ballast and rake it level. This is known as a blinding coat.
Remove the four corner pegs and lines. The sub-base height pegs will remain buried in the sub-base.
The first step in creating your new patio is marking out the space.
You'll also need to calculate and mark out the fall. The fall is a slight slope across a paved area that helps surface water to drain away easily. A patio is still level with a fall as the gradient is so gradual.
If possible, dry lay the patio to check that your measurements are correct. This is also an opportunity to mix up paving from different pallets - important if you have natural stone slabs as it'll help to blend any varying shades.
Lay out the paving slabs in the desired pattern, either where you plan to build your patio or on a clear, flat area of lawn. Allow for your preferred joint size between each slab.
Measure the length and width of the paving area to confirm the final dimensions of your patio. Move the slabs out of the way, making a plan on paper of what goes where so you can put them back in the same location.
Mark out the area for the sub-base using wooden pegs and a builders line. Ideally add an extra 5 to 10centimetres (cm) to every edge of the patio measurement. This will make the sub-base slightly bigger than the finished patio giving it a more secure foundation.
Place a wooden peg in each corner and run a builders line between each peg to provide a straight edge for the sides of the patio. Use a builders square to make sure the corners are square.
As a final check, measure the diagonals to make sure they are the same length. If they're not, measure each side again and adjust until your diagonals match.
Calculate the fall for your patio, using the final dimensions confirmed at the end of step 1.
The ideal fall is dependent on the type of paving slabs being laid.
If using textured paving slabs – the ideal fall for a patio is 1 in 80. That is a 12.5mm drop in level per metre.
To calculate the fall:
Multiply the required fall (e.g. 12.5 or 16mm) by the length of the sloping side of the paved area in metres (m). This will give you the total difference in height required between the highest and lowest point of the patio.
For example, if you are building a patio 3m long with textured paving, you will require a fall of 12.5mm per m. Allow a total fall of 37.5mm from the highest point of the paved area to the lowest.
If building a patio next to a house, garage or outbuilding, the paved area should slope away from the walls. You can choose the slope direction if there are no walls on any side.
Cut the turf into strips with a lawn edger (to give a neat line) and lift using a spade.
Roll up and save some of the turf in case you need to fix any gaps between your existing lawn and the paved surface.
Calculate the necessary depth for the sub-base.
For this project, we're digging to a depth of 215mm at the highest point. This is so we can lay:
All of these layers add up to give the necessary depth for digging.
Once calculated, dig the area to the correct depth using a spade.
Peg out the final surface level of the sub-base.
Take a number of wooden pegs (600mm tall and pointed at one end is ideal – these can either be made or purchased). From the top of the peg, measure the depth of the sub-base (100mm) and mark a line clearly on the peg using a pen or pencil.
Hammer a row of these marked pegs – spread at 1m intervals – across the highest side of the site. Hammer them in until the marked line is level with the excavated earth.
Use a long piece of timber as a straight edge to make sure that all of the pegs are level with each other and remedy if not.
Hammer in the next row of wooden pegs in line with the first, exactly one metre away.
Repeat until all rows of pegs are laid.
Set the fall for the sub-base. This ensures that when the sub-base is laid, the gradual slope of the fall will be present in the sub-base.
Measure and cut a small strip of wood to the required drop in height of the patio per metre. In our example in step 3, we calculated a fall of 12.5mm would be needed. This piece of wood is known as a levelling shim.
Nail the shim to the underside of one end of a 1m-long straightedge.
Lay the straightedge to rest between two pegs – the first peg from the first row and the first peg from the second row. The shim should face down into the top of the second row peg. Lay a long spirit level on top of the straight edge. The reading should show that the second peg is higher than the first one.
Remove the spirit level and straightedge and carefully hammer the second peg until you get a level reading when the straightedge, shim and spirit level are laid on top again. A level reading confirms that the peg has been hammered into the ground at the correct depth for the fall.
Dig, fill or tamp the ground as necessary until the peg is at the right depth.
Repeat Step 8 for all of the pegs in the second row.
Continue with the remaining rows.
You'll need to remove a depth of top soil equal to the depth of your sub-base, plus the thickness of your paving and mortar (at least 25mm). If you have firm well-drained soil, your sub-base should be 100mm deep - but if you have soft ground, it should be deeper. You'll need to clear an area that's slightly larger than your paved area will be. And if you're building a patio next to your house, make sure the level of the finished surface is at least 150mm below the damp-proof course.
The depth of the sub-base for a driveway depends on what you plan to pave it with. If you're laying concrete slabs, you'll need to allow 150mm of compacted hardcore plus 125mm of concrete. Or if you're laying paving blocks, allow 150mm of compacted hardcore and 50mm of sand
Mark out the area for your sub-base with builder's lines attached to wooden pegs. Use a builder's square to ensure the corners are square before you start digging. And as a final check, measure the diagonals to make certain they're the same.
Cut the turf in strips with a spade and roll it up. It's well worth saving some of it in case you need some to put in between your lawn and the paved surface.
Dig the area to the right depth and use marker pegs to mark the finished hardcore level - taking the needed fall into account.
Tip in enough hardcore to fill your sub-base to just above the top of the pegs.
Compact the hardcore with an earth rammer or petrol-powered vibrating plate compactor.
Cover the surface with a thin blinding coat of sharp sand or all-in ballast, then rake it level.