Choose pedestals, a laying bed or bonding
On pedestals, slabs span between supports and must be declared suitable for this use. Bed-laid slabs bear on a confined, free-draining foundation. Bonded slabs adhere to a stable, prepared rigid substrate using a compatible exterior system.
Required thickness, format and capacity depend on the method and product. A slab approved for one method is not automatically suitable for the other two.
Measure and set out the pattern
- 1Joists
- 2Pedestals
- 3Centre-to-centre grid
Measure the area, place visible datum lines and choose a start point that avoids narrow strips. Count whole slabs, cuts, spares and additional pieces required by patterns or diagonal layouts.
Calculate slab quantities and cutting allowanceTesCalculs→Prepare the appropriate substrate
- 1Boards
- 2Joists
- 3Pedestals
- 4Compacted aggregate
- 5Geotextile
- 6Ground
Over natural ground, remove unstable layers and build the foundation designed for the soil. For bonded work, assess flatness, cracks, fall, moisture and movement joints before applying any product.
Calculate aggregate for the foundation layerTesCalculs→Lay slabs on pedestals
- 1Joists
- 2Pedestals
- 3Centre-to-centre grid
Set pedestals out to the slab manufacturer’s pattern, adding supports specified for large formats, cuts and edges. Level the surface without closing the joints and retain access to outlets.
Calculate the pedestal grid for my slabsTesCalculs→Lay slabs on a granular bed
Screed a compatible laying bed over the compacted, laterally restrained foundation. Place each slab without disturbing the bed, maintain the designed fall and use the specified joint fill. Layer build-up depends on soil, climate and loads.
Bond slabs to a rigid base
Use slabs, substrate preparation, adhesive and grout designed together for exterior exposure. Follow the technical documents for priming, adhesive coverage, thickness, temperature and waiting times.
Estimate adhesive for the patio slabsTesCalculs→Finish edges, joints and access points
Restrain edges with the designed detail, continue required movement joints and make sure no finish traps water. Keep inspection points and drainage accessible and replace unstable or damaged slabs promptly.