How do I lay patio tiles around a drain or drainage channel?

Installation of patio slabs around a floor drain or drainage channel can be carried out in two ways.

The floor drain or drainage channel may remain open, with a drainage grate set flush into the patio slab surface. Alternatively, patio slabs can be laid over an existing load-bearing grating.

Where patio slabs cover the opening, the grating beneath carries the slabs. The slabs must not span the opening without adequate support. Rainwater passes through the water-permeable patio slabs and, via the drainage channels on the profiled underside, to the floor drain or drainage channel.

Whether the remaining flow area and inlet area are sufficient depends on the area to be drained, the amount of rainfall, the fall and the capacity of the drain. Additional holes in the patio slab can improve water entry directly above the grating; drill these with a wood bit. The patio slab must remain removable for inspection and cleaning, and the grating beneath must also be removable.

If the drainage capacity beneath the patio slabs is insufficient, the floor drain or drainage channel remains open. The patio slabs are then cut to fit around the opening. An exposed drainage grate is flush with the patio slab surface and allows water to enter the drain directly.