All paving should incorporate good drainage, in particular when laid on a bedding of sand either over roadbase or concrete.  It is essential that both the roadbase and the bedding sand can drain freely.

After extended rain, water can penetrate through the joints into the bedding sand.

Sand Bedding Over Concrete
If not drained correctly when coarse sand is bedded over concrete the sand will become saturated and the pumping action caused by traffic will expose the pavers to water bourne staining, chipping, substrate subsidence, etc. and may become unsightly and possibly unsafe.

Ensure that the concrete on which the pavers are laid has sufficient drainage in the relevant direction to allow the coarse bedding sand to drain off any water that penertrates the paved surface through the joints.
If the perimeter / border coarse is to be bedded with mortar as a means of assisting to retain the bedding sand then insert 25mm thick drainage conduits at intervals of 300mm around all perimeters, covering the ends of the conduit with a geo fabric on both ends to prevent them from blocking when screeding the bedding or backfilling the surrounds.
Do not mortar bed the perimiter coarse in a manner that will cause water ponding in the coarse bedding sand.

Sand Bedding Over Roadbase
If not drained correctly when sand bedded over roadbase the action caused by traffic will cause water penetration through the coarse bedding sand and into the roadbase beneath exposing the pavers to water bourne staining, chips, subsidence, and become unsightly,  and possibly unsafe.
Ensure the edge restraint around  the perimiter/border coarse allows the coarse bedding sand to drain freely by inserting 25mm thick drainage conduits at interviles of 300mm around all perimiters, covering the ends of the conduit with a geo fabric on both ends to prevent them from blocking when screeding the bedding or backfilling the surrounds.

Consult your tradesman or call iPave and one of our friendly technical staff will be pleased to assist you with any further explanation you may require.