Drainage gravel is a graded clean stone aggregate, typically 10mm to 40mm in nominal size, used as bedding and surround material around drainage pipes. It supports the pipe along its length, distributes loads from above and allows minor groundwater flow without trapping silt that could undermine the pipe. UK installations follow BS EN 1610 for pipe laying and Building Regulations Part H. The gravel should be free from clay fines, sharp angular edges and excessive dust to avoid damaging the pipe wall during compaction. On a typical residential trench across Greater London, 100mm of bedding is laid below the pipe and a 150mm surround is provided to the pipe crown. Granite, limestone and gritstone aggregates are commonly specified depending on local supply. The material is delivered to site by bulk bag or tipper depending on quantity.
Drainage gravel (10 to 40mm)
Graded clean stone aggregate used as bedding and surround for drainage pipes.
