Rates are UK national (non-London): central London and constrained urban sites typically run dearer — adjust the labour, plant and access lines in the build-up accordingly.
Trench excavation
per m³ · excavate to stockpile
£6 – £23 / m³
What is it
The machine excavation of trenches for strip and pad foundations and for buried services, dug with a 13–20 t tracked 360° excavator on a narrow trenching bucket and trimmed by an in-trench banksman, priced per in-situ (bank) m³ of excavated material. This headline is a dig-to-stockpile rate — spoil is cast alongside the trench to re-use as backfill, not carted away. Output, the main driver, is set by the trench context, in three bands:
Wide / open — a foundation trench with open machine access, dug fast to stockpile.
Standard — a typical foundation or service trench; the default rate.
Confined / supported — deep, around services or boarded / battered, worked slowly.
Rate range by dig context
Wide / open£6 – £8 / m³
Standard£9 – £12 / m³
Confined / supported£18 – £23 / m³
Budget rate per m³.
3 key cost drivers
Trench context & depth
Output is the main lever of the rate. An open foundation trench digs fast to stockpile; a deep, confined or supported trench worked around services runs at a fraction of that output, lifting the cost per m³.
Ground & dig difficulty
Soft to firm soil is the default. Stiff clay, made ground or rock slows the machine and drops the achievable output a class, moving the dig to a lower-output row.
Location
London and the South East typically add around 20% to labour and plant.
Estimator
Budget rate generator
£9 – £12 / m³
Covers the excavator, its two-man gang and O&P, dug to on-site stockpile · excl. cart-away, support, prelims & VAT
Exclusions
Carting spoil away — muck-away haulage & tip fees, on the bulked volume (a separately priced disposal item)
Earthwork support — trench-box / timbering hire (an attendance for deep or unstable trenches)
Site dumper & forward haul / distribution of arisings (an attendance, in main-contractor prelims)