Keying in Edging Detail Setts
One of the commonest problems that arise when a design calls for an edging detail – usually a different colour and size of edging material – is the risk of the detail failing due to not being an integral part of the main body of paving. Frequently, the detail product is thicker than the main paving (mainly 20mm slabs), often block paving cuboids, either 50mm or 75mm thick, requiring a different laying bed depth.
It is recommended that the sub-base (concrete or MOT Type 1) is extruded beyond the edge of the main paving, set at a lower level if necessary to receive the thicker products, but essentially, to tie the edge in with the main body, and not simply add it almost as an afterthought.
It is essential to link both types of paving together to prevent migration and separation of the two, and this may be achieved by extruding either a strip of reinforcing mesh – 60cm under the paving and as far as the edging (200mm?) – or stainless-steel brick ties, 50% under the paving and 50% under the edging block/sett. This will bind the two laying beds together and prevent lateral movement.
In some circumstances, on soft ground, or where the edging is higher than the neighbouring lawn, to consider using either a metal or slate edging restraint (see Edging Restraints).
