Formation level in construction for patio edge restraint

The formation beneath patio slabs must be level, have adequate load-bearing capacity and be well drained. For ground-level patios, the substrate must be built to withstand frost. The precise construction depends on the type of patio slab and the existing site conditions.

For a ground-level patio, the sub-base comprises a formation with adequate load-bearing capacity and adequately compacted frost-protection and load-bearing layers. Rigid concrete or natural stone slabs are normally laid on an evenly screeded laying course of chippings. Depending on the system, ceramic patio slabs may be installed on a laying course of chippings, on adjustable pedestals or in a bonded system. Timber and WPC decking require a suitable substructure.

Patio tiles made from PU-bound rubber granules require continuous support and cannot be supported at individual points on adjustable pedestals. On sound concrete, asphalt, concrete block paving or natural stone, PU-bound rubber granule tiles can be loose-laid without a mortar bed. The existing substrate must allow water to drain at an adequate fall towards an outlet or infiltration area.

On an unpaved substrate, first create a level formation with adequate load-bearing capacity. A gravel grid laid across the full area can provide stable, water-permeable support on this formation. Fill the gravel grid cells completely with suitable chippings. Depending on substrate conditions and frost exposure, a compacted frost-protection and load-bearing layer beneath the gravel grid may also be required. A concrete slab is not required for a gravel-grid construction.