How Much Sub-Base Do I Need For A Patio? | Checkatrade
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How much sub base do I need for a patio?

For most patios, spreading a 100mm layer of sub-base (ideally MOT Type 1) on top of the soil will give you a suitable foundation – once compacted.

It’s important to compact your sub-base at least twice, to ensure that it’s properly condensed to provide a solid base on which to lay your patio.

Always check for any sinking areas and add an extra layer of sub-base in those areas, where needed, and compact until the whole patio area is flat and smooth.

What is the ideal patio sub-base depth?

As a general rule, having a patio sub-base depth of 100mm is considered to be a good standard layer. Some may say that you can get away with a slightly thinner layer if you’re installing a light patio, but we’d always recommend going for 100mm to create a sturdier foundation.

How much MOT type 1 do I need for a patio?

When preparing the sub-base for your patio, you’ll need approximately 1 tonne of MOT type 1 per square metre.

If you plan to install the patio yourself, it’s always useful to seek expert advice from local patio installers or representatives at your local DIY store or home improvement retailer.

Tips for preparing sub-base for a patio

To help you prepare the sub-base for your patio, here are a few of our top tips:

  1. Allow enough depth for all layers of your patio – when digging down to lay your sub-base, make sure you dig deep enough to allow for your sub-base, blinding coat, mortar and paving slabs.
  2. Calculate and mark out the fall – The fall refers to the slight slope that you want to have across your patio to ensure that surface water drains away easily. An ideal fall should be roughly a 12.5mm drop per metre for textured paving slabs, or 16mm per metre for flat or smooth paving slabs.
  3. Always compact your sub-base – Use a plate compactor at least twice over your entire area of the sub-base and add more sub-base wherever needed to reach 100mm.
  4. Add a blinding coat – Once your sub-base is in place and compacted, cover it with a 10mm layer of sharp sand or all-in ballast to provide a clean, level and dry working surface to lay your mortar.

Want professional help for your patio? Check out how to find and hire the best local patio contractors near you.

You can also find out about prices in our guide on how much it costs to lay a new patio.

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