Drainage bed and manhole location
10 mm
Substructure drainage pipes must be laid on a suitable bed of granular material, such as 10mm pea gravel, to provide stable support and protect the pipes from ground movement
Substructure drainage pipes must be laid on a suitable bed of granular material, such as 10mm pea gravel, to provide stable support and protect the pipes from ground movement. Manholes should be strategically located to avoid disrupting future landscaping or paving layouts, ensuring ease of access.
Basis in regulation
BS EN 12056
Read the source
How to check it on site
Confirm drainage pipes are bedded on granular material and manhole positions avoid conflict with proposed external finishes.
Common failure
Drainage pipes are not adequately bedded, leading to potential damage or blockages, and manholes are poorly located, requiring expensive rework for landscaping.
Last updated 23 August 2026. This is our editorial summary of publicly available regulation, not building control approval or a warranty determination.