Work out what size skip, how many skips, or how many grab lorry loads you need for the soil you're digging out.
Soil takes up more room once it's dug: about 30% more for clay, 20% for chalk and 15% for sand or gravel. We work out the loose volume from what's in the ground.
We estimate the weight from the volume in the ground: about 1.8 t/m³ for clay and 1.6 t/m³ for chalk or sand.
UK skips are sold in cubic yards (1 yard ≈ 0.76 m³). Soil is only allowed in skips up to 8 yards, and each has a weight limit of roughly 1 tonne per yard. We find the fewest skips that hold the spoil by both volume and weight. A grab lorry takes about 16 t a load.
These are estimates for ordering materials, not a structural design. Check site conditions, and anything unusual, with a qualified builder or engineer.
Usually a 4- or 6-yard skip. Soil is so heavy that most firms won't let you fill anything bigger than 8 yards with it, and even then often only three-quarters full.
A 6-yard skip holds about 4.6 m³ of loose soil. With clay you'll usually hit its weight limit (about 6 tonnes) first, at roughly 3.3 m³ dug out of the ground.
For more than about 8–10 tonnes of soil, often yes. A grab lorry takes around 16 tonnes in one load and needs no road permit if it can reach from the road.
Only if it goes on the road or pavement. The hire firm usually arranges the council permit for a fee. On your own drive, no permit is needed.