Soil and Hardcore Skip Cost UK 2026: Inert Rates Save 20-30%
Soil and hardcore are the two most expensive types of waste to dispose of through a standard mixed skip, because they are heavy enough to fill the weight limit before the visible volume looks half full. The skip-hire industry has a specific answer to this problem: the inert-only skip. By accepting only clean inert material (soil, brick, block, concrete rubble, broken paving, ceramic tiles, glass), the operator can route the entire load through the much cheaper inert-waste landfill stream rather than the standard mixed-waste stream, and pass most of the saving back as a lower headline price.
The saving is structural, not promotional. HMRC Landfill Tax operates two rates: the standard rate (£103.70 per tonne from April 2025) for general mixed and biodegradable waste, and the lower rate (£3.30 per tonne from April 2025) for naturally occurring inert materials and inactive construction waste. A 6-yard inert skip filled to its 4 to 5 tonne capacity pays roughly £15 in landfill tax. A 6-yard mixed skip filled to its 3 tonne capacity pays roughly £310 in landfill tax. That difference is the engine behind the 20 to 30 per cent inert-only discount you see in operator quotes.
The catch is strictness. The transfer station classifies a load as inert only if it is genuinely uncontaminated. Even small quantities of wood, plastic, plasterboard, or biodegradable material reclassify the entire load to standard mixed waste, attracting both the full landfill tax and typically a contamination surcharge of £80 to £200. Inert-only skips are therefore best used when you are confident you can run a clean stream, ideally with separate disposal arrangements for any non-inert waste from the same project.
Inert-Only vs Mixed Skip Pricing
| Skip size | Mixed waste price | Inert-only price | Saving |
|---|---|---|---|
| 4 Yard (Midi) Inert | £100-180 | £80-145 | ~20% |
| 6 Yard (Builders) Inert | £150-250 | £120-200 | ~20-25% |
| 8 Yard (Large) Inert | £200-350 | £160-275 | ~20-25% |
| 12 Yard (Maxi) Inert | £250-450 | £200-365 | ~20-25% |
Inert skips are available in all standard sizes but most commonly stocked at 4, 6, and 8-yard because these match the practical weight capacity for a single inert load. London inert pricing runs 30 to 40 per cent above the national average, mirroring the mixed-waste regional pattern.
What Counts as Inert vs Not
Accepted as inert
- Clean soil and subsoil
- Brick rubble (clean, no mortar contamination is fine)
- Concrete rubble (broken slabs, blocks, kerbs)
- Broken paving and kerb stones
- Ceramic tiles (un-bonded, no adhesive residue beyond surface)
- Stone and natural masonry rubble
- Sand and gravel
- Broken glass (clean, free of frames)
Not accepted in inert skip
- Plasterboard (gypsum, separate rules: see plasterboard guide)
- Wood (any timber, even clean offcuts)
- Plastic of any kind (sheeting, packaging, plant pots)
- Carpet, underlay, fabric
- Metal items beyond incidental fixings
- Vegetation, soil with significant root mass, turf
- Contaminated soil (oil, fuel, paint residue, chemical staining)
- Asbestos-containing materials (separate hazardous route)
The classification system follows the European Waste Catalogue codes used in the Defra waste classification technical guidance. Inert-accepted material falls under EWC chapter 17 (construction and demolition waste) for clean fractions. Contaminated soil falls under chapter 17 05 03 (soils and stones containing hazardous substances) and is not accepted in inert skips.
Weight Reality: What Fits in an Inert Skip
Inert skips have higher weight ratings than mixed-waste skips of the same volume, but they are still bounded by the lorry's safe lifting capacity. Practical capacity by material:
- Soil (topsoil): roughly 1.5 tonnes per cubic metre. A 6-yard inert (4.5 m³) at 4-5 tonne rating handles around 3 cubic metres of soil. The skip looks two-thirds full visually.
- Brick rubble: roughly 1.9 tonnes per cubic metre. A 6-yard inert handles around 2.3 cubic metres of brick. The skip looks half full visually.
- Concrete rubble: roughly 2.4 tonnes per cubic metre. A 6-yard inert handles around 1.9 cubic metres of concrete. The skip looks 40 per cent full visually.
- Mixed soil and rubble: roughly 1.8 tonnes per cubic metre on average. A 6-yard inert handles around 2.5 cubic metres. The skip looks 55 per cent full visually.
The visual emptiness at weight limit is the most common cause of overweight surcharges. Always confirm the weight rating with the operator at booking, and stop loading at the rated weight rather than the visual top. Operators sometimes provide a load-monitoring strap or a skip-mounted weighing system on commercial sites for accurate fill management.
Projects Where Inert-Only Saves Money
Driveway lift and re-lay
Block-paving or tarmac lift on a typical 4 to 6-car driveway generates 2 to 4 cubic metres of clean inert rubble. An inert 6-yard saves £30 to £60 versus mixed.
Patio break-up
Lifting a 20 to 40 square-metre patio generates 1.5 to 3 cubic metres of clean slab rubble. Inert 4 or 6-yard works well.
Garden landscaping with level change
Excavating to lower a garden level generates significant soil volume. Inert 8 or 12-yard saves materially on the soil disposal cost.
Single-storey demolition
Garage or outbuilding demolition generates a clean rubble fraction (brick walls, concrete base, roof tiles) that suits inert-only routing. Separate the timber roof rafters into a wood-waste skip for the cleanest segregation.
Wall removal (internal masonry)
Removing a load-bearing internal masonry wall generates clean rubble that suits inert-only. Strip out the plasterboard skim separately if present.
Foundation excavation
New-build foundation digs generate large soil volumes. Inert disposal is essentially the only economically viable route at this scale; some sites also negotiate beneficial-use diversion if the soil is clean and a nearby landscaping project can take it.
Grab Lorry Threshold
For inert-only loads over around 8 to 10 tonnes, a grab lorry is usually cheaper per tonne than an inert skip. A grab takes 10 to 12 tonnes in a single 30 to 60 minute visit at £250 to £500 nationally, no hire period and no permit. See our skip vs grab lorry guide for the full economics.
Frequently Asked Questions
How much does an inert-only skip cost?
An inert-only skip (soil-only, hardcore-only, or clean rubble-only) typically costs £120 to £200 for a 6-yard nationally as of May 2026, 20 to 30 per cent below a mixed-waste 6-yard at £150 to £250. The saving comes from the much lower landfill tax rate that applies to clean inert waste (£3.30 per tonne lower rate vs £103.70 per tonne standard rate at April 2025) and the simpler processing route at the transfer station.
What counts as inert waste?
Inert waste is material that does not break down, react chemically, or contaminate other waste under normal landfill conditions. The standard inert waste categories accepted in inert-only skips are: clean soil and subsoil; brick, block, and concrete rubble; broken paving slabs and kerb stones; ceramic tiles (un-bonded); broken glass; and clean uncontaminated hardcore. Anything mixed with plasterboard, wood, plastic, organic matter, or contaminated soil is no longer classed as inert and goes in a mixed-waste skip.
What is the heavy weight limit on a soil-only skip?
Inert-only skips are engineered for the weight of inert material, which means they have a higher weight rating than the mixed-waste version of the same size. A 6-yard inert skip typically rates at 4 to 5 tonnes (versus 1.2 tonnes heavy limit on a mixed 6-yard), an 8-yard inert at 5 to 7 tonnes. This means you can fill an inert skip almost to the visual top with soil or rubble without hitting weight limit, where a mixed 6-yard hits its heavy limit at roughly one-third full.
Can I put a small amount of wood in an inert skip?
No. Inert skips are strictly inert-only at the transfer station because contamination breaks the classification and forces the load to be reclassified to mixed waste, attracting the full landfill tax rate. Even small quantities of wood, plastic, or biodegradable material will trigger reclassification and a contamination surcharge (typically £80 to £200 per load). If your project has any non-inert waste, either run an inert skip alongside a mixed skip or accept the mixed-waste pricing throughout.
Is an inert skip cheaper than a grab lorry?
For small to medium volumes (up to around 5 tonnes), an inert skip is typically cheaper because the delivery and collection costs are amortised over a hire period that you control. For larger volumes (10+ tonnes), a grab lorry is usually cheaper per tonne because it can take 10 to 12 tonnes in a single load with no hire period. Crossover point depends on your local market: in most regions, grab lorries win above 8 to 10 tonnes of clean inert.