Minimum cover for mechanical compaction

150 mm

Before mechanical compaction of trench backfill, a minimum of 150mm of material should be placed above the pipe to prevent direct damage.

Basis in regulation

BS EN 1610
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How to check it on site

Verify that there is at least 150mm of cover over the pipe before any mechanical compaction is started.

Common failure

Starting mechanical compaction too early, damaging the installed pipe.

Last updated 23 August 2026. This is our editorial summary of publicly available regulation, not building control approval or a warranty determination.

Related dimensions at this stage

Minimum

Gradient of a 100 mm foul drain

1 in 80 (steeper for runs with fewer appliances)

100 mm foul drain serving at least one WC

Minimum

Depth of cover to a buried drain

600 mm under gardens and other areas not subject to vehicles; 900 mm under roads and driveways

Buried foul or surface water drain outside the building footprint

Minimum

Distance from a soakaway to a building

5 m

Surface water soakaway serving a dwelling

Minimum

Height of a ventilating stack terminal above an opening

900 mm above the top of any opening within 3 m horizontally

Open ventilating stack terminating at roof level or on an external wall

Maximum

Spacing between drainage access points

45 m

Straight run of buried drain between access points

exact

Backfill compaction protocols

300 mm

Trench backfill must be well compacted in layers no deeper than 300mm to achieve stable ground