Maximum and minimum cover depths for twinwall installation

Advice and guidlines for installing JFC twinwall at maximum and minimum cover depths.

The following advice is recommended by JFC Manufacturing Ltd for installing JFC corripipe twinwall, available at JDP. For other brands of twinwall, installation advice may differ.

Minimum cover depths

Application Minimum cover depth
Non-trafficked areas 0.6 m
Trafficked areas not subject to Highways Agency or National Roads Authority requirements 0.9m to finished surface
Trafficked areas subject to Highways Agency or National Roads Authority requirements. 1.2m to finished surface

Maximum cover depths

Twinwall Pipe stacked up

Maximum cover depths are typically between 6-10 meters when installed in accordance with series 500 of MCDHW Volume 1.

The actual maximum allowable cover depth is often dependant on installation parameters, this is often well in excess of 6-10 meters. These parameters are:

  • The native soil stiffness
  • The pipe bed and surround stiffness
  • The size of the trench
  • The density of the overburden
  • Hydrostatic loading
  • Factor of Safety
  • Maximum allowable deflection limit

JDP’s technical support team can assist you with calculating installation depths for specific site conditions.

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