Skip and Waste Estimator

Most single-storey extensions get through several builder's skips across the whole build, and one 6-yard load from a skip hire company hires for £200 – £400 at 2026 rates. This estimator turns your floor area, demolition scope, and strip-out work into a waste volume in cubic metres, then tells you how many skips that fills and what the hire is likely to cost.

Enter the extension floor area, add any internal walls being knocked through, tick the boxes for an old kitchen or bathroom coming out, and the tool recommends a skip size and shows the cost above. It is built for early planning, so you can budget for waste before the first delivery arrives and sanity-check whether your builder's quote covers it.

What drives your waste volume

Excavation soil is the biggest single waste stream on most extension projects. Digging the foundations throws up far more spoil than people expect, and it is heavy, so it fills skips fast. On top of that sits general construction waste (offcuts, packaging, broken blocks, and rubble) plus anything you strip out of the existing house before the new work starts.

The estimator adds those streams together and recommends a builder's skip for typical jobs. If the foundation dig produces a large volume of clay or spoil, a grab lorry is often the cheaper route: one load costs £150 – £420 and carries about the same weight as two 8-yard skips, which would run £500 – £1,000. Ask your builder whether they plan to muck away soil by grab lorry or tipper before you order skips for it.

Permits, welfare, and what the estimate leaves out

The figure above is skip hire only. If the skip has to stand on a public road or pavement you also need a skip permit from the council, which runs from £20 per week a week in cheaper areas up to £100 per week in London boroughs. Placing a skip on the highway without one is a criminal offence under the Highways Act 1980, so it is worth checking early. A skip that fits on your own driveway needs no permit.

Skip hire is one line in the wider site preliminaries: the upfront costs of getting the site ready, including welfare, access protection, and insurance. Across a whole extension, skip hire and basic welfare together typically land at £600 – £1,600, so treat the per-skip number as one part of that total.

A worked example

Take a 30m² single-storey rear extension where the old kitchen is being ripped out first. Enter the floor area, tick the kitchen strip-out, and the calculator combines the foundation spoil, the general construction waste, and the kitchen rip-out into one volume, then recommends a builder's skip and shows the count and cost above.

At £200 – £400 for a 6-yard load, or £250 – £500 for an 8-yard, the per-skip rate is the number to check against your builder's quote. If the dig turns up more clay than expected, moving that soil by grab lorry instead of skip usually saves money on the heaviest single stream. See skip hire and site setup for the full checklist of what to arrange before day one.