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How to Lay a Patio

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I built my patio from scratch and love sharing my tips and tricks with readers.

How to Lay a Patio for Beginners

This article will teach you how to lay a basic garden patio in four easy steps. We are approaching the patio project as beginners, having never laid one before. Although it can be hard physical work, there is no reason why anyone with moderate DIY skills shouldn't attempt to lay their own simple garden patio.

A garden patio can be as simple or as complex as you choose; this article is for a simple patio laid with regular-shaped concrete flagstones.

Gravel margins allow for small measuring errors as well as preventing splashback from rain making your wall damp

Gravel margins allow for small measuring errors as well as preventing splashback from rain making your wall damp

Step 1: Plan the Patio

Yes, I know it's a bit dull when you really want to get started on a project, but time spent now really will make life easier and the project run more smoothly and cost-efficiently in the long run.

Things to think about include:

  • Which way will the patio slope? Of course, you don't want an obviously sloping patio, but you do need a shallow regular slope to allow surface water runoff away from the house. A slope of 16mm/meter (or 5/8" per yard) should be adequate.
  • What level are you working to on your brickwork? Flagstones should be laid at least 150mm (6") below the damp proof course of your house, as there will be splashback from rain against the house's brickwork.
  • Plan for a 100mm margin of gravel between the wall and flagstones. This helps drainage of surface water and gives you a little bit of margin of error with your measurements. If you wanted, you could plant a climbing plant on the border.
  • Plan your area to minimize (or hopefully eliminate) the need to cut flagstones.
  • What sort of base do you need? For the simple garden patio, a base of 35mm of sharp sand should be adequate on top of compacted soil. A peaty or clay soil may require you to lay a hardcore layer (rough gravel/stone/broken brick) of 75mm below the sand. Although we're not really covering it here, if you were to be laying a patio for heavier loads, you would also want this hardcore layer.
  • What sort of flagstone will you use? Larger flagstones are harder to handle, but you need to lay less, making getting your levels or slope easier. Regular squares or rectangles are easier to plan and will require less cutting. A garden patios standard thickness is approximately 30-40mm; more heavy-duty 50mm flagstones are available for weight-bearing patios but are more costly and significantly heavier to handle. If you are doing it by yourself, don't consider larger than 600x600mm (2'x2') of the 30-40mm variety.

Step 2: Prepare the Base

Once you have your building plan in hand, it's time to start preparing the patio base.

  1. Clear the surface vegetation and topsoil, excavating to a depth of; flagstone thickness + 35mm/1.5" for the sharp sand layer (plus a hardcore layer if required). It's a good idea to lay any flagstones a couple of centimeters below the level of any surrounding grass to prevent damage to your lawnmower.
  2. Cut some wooden pegs with markings for the different layers as above. You should notch these with a saw at these levels. For example, the level of the base of the flagstone/top of the sand layer and the level of the bottom of the sand layer. The top of the peg is where the top of the flagstone will be level.
  3. Drive these pegs into the ground to mark the boundary of the patio, and using the notches, run some string between them at the lowest layer.
  4. Using a long piece of wood as a straight edge, place this over the top of the pegs, then place your spirit level on top of this piece of wood to ensure you've got the levels correct. Don't forget to allow a slope to allow water runoff. (To be precise, you could cut a piece of wood to the thickness of the total fall across the slope, place this on top of the lowest peg, and using your spirit level, adjust the depths of the pegs so that the straight edge is level.)
  5. Level the soil to the string level using a rake and compact it (using a garden roller is the easiest way to do this).
  6. Now move the string to the higher notch on your peg and level the sand to this level.
  7. Tamp the sand down using a piece of wood with a straight edge.
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Use spacers between the flagstone to keep joint equal and straight

Use spacers between the flagstone to keep joint equal and straight

Using an angle grinder cut around any obstacle that you can't move

Using an angle grinder cut around any obstacle that you can't move

Patio before joints are filled

Patio before joints are filled

Step 3: Lay the Flagstones

  1. Lay the edge flagstones on top of the sand in both directions from a corner. Now is a good time to double-check all measurements! Is the level right? Is the fall correct? Use your straight edge to check these. Don't get too stressed yet; it needs to be close to right but not yet perfect!
  2. Use spacers between the flagstones to ensure joints are straight and equal. You need at least two spacers along each edge.
  3. Once you are satisfied with the position of these edge slabs, lift them one at a time and put five fist-sized blobs of mortar under each flagstone, one at each corner and a fifth in the center, and lay them down again on top of this. Weight-bearing patios should be laid on a solid layer of mortar.
  4. Using a large hammer on a thick piece of wood to protect the surface of the flagstone, tap the flagstone to return it to the level you want. This is where you need to get the levels to spot on. This is the slow part, and it can be frustrating as you may need to lift the flagstone and re-lay it if it is rocking or too high or low in one area and you can't solve it with your hammer!
  5. Once you are happy with these flagstones, lay the rest of the flagstones working from those already laid, using your spacers all the time.
  6. If you have any obstacles next to the wall, e.g., drains or waste pipes, you may need to cut around them using an angle grinder. I hired a Makita angle grinder from my local hire shop for £15 and had to buy a stone blade for £3. Diamond blades can be hired but are really only worth it if you have to cut a lot of flagstones. My hire shop charge £20 to hire plus a charge for the amount of blade you use.
  7. Remove the spacers before the mortar dries. Leave the joints empty for two days to allow the mortar to dry, and don't walk on the flagstones during this time.
Pour dry mortar into the joints

Pour dry mortar into the joints

Brush the mortar into the joint

Brush the mortar into the joint

Joints after dry mortaring

Joints after dry mortaring

Step 4: Fill the Joints

  1. Fill the joints with a dry mortar mix, as shown above.
  2. Once you are happy with this, use a watering can with a fine spray head to water over the joints and leave it to dry.
  3. Use a mortar mix to fill any gaps around drains or waste pipes if necessary.
laying-a-patio-a-step-by-step-guide

Step 5: Enjoy!

Once all the mortar is dry, get your deckchair out, open a beer and relax; you've earned it!

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

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