Garden Projects · 10 min read · Intermediate

How to Plan & Lay a Patio: Sub-Base, Falls, Bedding & Joints

Understand the build-up beneath paving, why drainage falls matter and how paving type changes the bedding and jointing system.

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Key points & steps

  1. Set out the finished patio footprint and confirm finished levels before excavating. Pay particular attention to doors, thresholds, drainage, air bricks and the building damp-proof course.
  2. Plan a positive fall so surface water drains to an appropriate location rather than toward the building. The exact fall depends on the paving and drainage design; heavily textured surfaces can need more fall than smooth paving.
  3. Excavate soft or unsuitable material and create a stable formation. Ground conditions and intended loading determine how much build-up is required.
  4. Lay and compact a suitable sub-base where required, in layers if necessary, and form the drainage fall in the sub-base rather than trying to create it by making one side of the mortar bed unusually thick.
  5. Choose the bedding system specified for the paving product. Natural stone, porcelain and concrete flags can have different mortar, primer and installation requirements.
  6. Lay full slabs from a controlled line and maintain the intended joint width. Avoid dot-and-dab bedding where the paving system requires a full, consistent bed.
  7. Cut edge pieces safely using appropriate equipment and PPE and avoid tiny slivers that are difficult to bed securely.
  8. Allow the bedding to gain sufficient strength before jointing or trafficking the paving, then use a jointing system compatible with the slabs and bedding.
  9. Keep drainage channels and movement details clear and inspect the patio after rain for standing water before considering the job finished.

Practical tips

  • The paving slab is only the visible layer; long-term performance depends heavily on the ground preparation and sub-base beneath it.
  • Do not assume the same bed and primer system works for every porcelain or natural-stone product.
  • Where paving approaches a house, finished levels and drainage deserve more attention than simply matching the garden level.

What you may need

  • Paving slabs
  • Sub-base material
  • Bedding materials specified for paving
  • Primer if required
  • Jointing material
  • Plate compactor where appropriate
  • Level/string lines
  • PPE

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