Shed Base Costs UK — What to Charge for Concrete, Paving and Grid Bases in 2026

Why a Proper Base Matters

The base is the single most important part of any garden building. A shed, summerhouse or log cabin is only as good as what it sits on. Put a timber building on uneven, soft or poorly drained ground and the problems are predictable: the frame twists, the door and windows jam, the cladding pulls apart at the joints, and the floor bearers sit in damp and rot out within a few years.

Almost every shed and cabin manufacturer states in their warranty terms that the building must be erected on a firm, level, well-drained base of the correct size. Skip that and the warranty is void. When you explain this to a customer, the better base sells itself — nobody wants to put a £3,000 log cabin on a few wobbly slabs and lose the guarantee. Your job is to give them a base that is firm, dead level, free-draining and slightly larger than the building footprint. Get that right and the building lasts decades.

Base Types and What to Charge

There are several ways to build a shed base, and the right one depends on the size and weight of the building, the ground conditions and the customer's budget. Here's a breakdown of the main types with current UK price ranges for a typical small-to-medium shed.

Concrete Base — the Gold Standard

A poured concrete slab is the strongest, longest-lasting base you can build, and the one to recommend for anything heavy or permanent. The method: dig out the area, lay and compact a sub-base of MOT Type 1 (typically 100mm), set up timber shuttering to the right level with falls, lay a damp-proof membrane, then pour and tamp a C20–C25 concrete slab around 100mm thick. For larger or heavier buildings you add steel mesh or rebar to stop the slab cracking.

For an average 8x6 to 10x8 shed this lands at £400–£900 supplied and laid, depending on access, ground and how much spoil has to go. As a per-m² figure, concrete bases work out at roughly £80–£140/m². Price toward the top of the range for poor access, sloping ground or where you're reinforcing the slab.

• Average 8x6–10x8 shed base: £400–£900
• Per m² supplied and laid: £80–£140/m²

Paving Slab / Patio Slab Base

Laying paving slabs on a compacted sub-base and bedding mortar is a popular middle-ground option. It gives a firm, level platform that's perfectly adequate for most timber sheds and summerhouses, and it's cheaper and quicker than a full concrete pour because you're not waiting on shuttering and curing. You still dig out, compact a Type 1 sub-base and bed the slabs on a sand-and-cement mix, leaving small gaps and falls for drainage.

Expect to charge £300–£600 for an average shed-sized paving slab base. It's a good upsell from a grid base and a sensible recommendation where the customer wants something solid but doesn't need the strength of concrete.

• Average shed paving slab base: £300–£600

Plastic Grid Base (EcoBase / ProBase)

Recycled plastic grid systems — sold under names like EcoBase and ProBase — are the fastest-growing shed base type in the UK. You lay a weed membrane, set the interlocking plastic grid out level, and fill it with gravel. The result is a firm, permeable base that drains freely and goes down in a fraction of the time of concrete. It's DIY-friendly, which means some customers buy the kit themselves — but plenty would rather pay you to dig out, level and fit it properly, and that's where your margin sits.

Charge £150–£350 for a fitted grid base on an average shed, or roughly £30–£55/m² including the dig-out, levelling and gravel fill. The grid kit and gravel are inexpensive, so the price is mostly your labour — which is exactly what makes these jobs profitable when you do them well.

• Average fitted grid base: £150–£350
• Per m² fitted: £30–£55/m²

Timber Bearer Frame Base

A pressure-treated timber frame sitting on concrete pads or paving slabs is sometimes used for smaller, lighter sheds, particularly where the ground is reasonably level and you want to lift the building clear of the soil. It's quick and keeps the floor well ventilated, but it relies on a firm, level set of pads underneath — the timber frame is only as good as what it sits on. Typically charged at £200–£450 depending on size and how much groundwork the pads need.

Gravel / Type 1 Base

At the budget end, a simple compacted MOT Type 1 or gravel base within a timber edging frame is the cheapest option, usually £120–£300. It drains well and is fine for lightweight sheds and bin stores, but it doesn't give a hard, level surface for the building to bolt down to. Recommend it only for light, temporary or small structures.

The Groundwork Breakdown That Drives Cost

Whatever base type you build, most of the cost — and most of the time — is in the groundwork underneath, not the finished surface. Understanding this breakdown stops you underquoting. The stages on a typical base are:

• Marking out and levelling: Setting out the base square and to size, with the right overhang, and establishing levels and falls.
• Excavation and spoil removal: Digging out the topsoil and any soft ground to the depth needed for the sub-base and slab. The dug-out spoil has to go somewhere — skip hire or grab-away disposal is a real, often-forgotten cost.
• Compacting the sub-base: Laying MOT Type 1 hardcore and compacting it in layers with a wacker plate. A properly compacted sub-base is what stops the base settling and cracking later.
• Shuttering and DPM: Setting timber shuttering to level for a concrete pour, and laying a damp-proof membrane to keep ground moisture out of the slab.
• The slab or surface itself: Pouring and tamping the concrete, bedding the slabs, or filling the grid.

Notice that the excavation, spoil disposal and sub-base happen on almost every job regardless of finish. That's why even a "cheap" grid base still has a sensible minimum price — the digging and disposal don't get cheaper just because the top layer does.

Concrete Quantities and Materials

For a concrete base, knowing your materials cost is how you see your margin. As a rough guide for an average 8x6 shed (around 4.5m²) with a 100mm slab on a 100mm sub-base:

• MOT Type 1 hardcore: roughly half a tonne to a tonne, around £30–£60 delivered.
• Concrete: about 0.45m³ of C20–C25. Mixing on site from sand, ballast and cement costs £70–£120 in materials; ready-mix delivered is more convenient on larger pours but carries a minimum-load charge that pushes small jobs up.
• Shuttering timber: a few lengths of treated timber and pegs, £20–£40.
• Damp-proof membrane: a roll covers several jobs, a few pounds per base.
• Mesh or rebar: only on larger or reinforced slabs, £25–£60 for a small base.

All in, materials on a small concrete base often come to £150–£280. Set against a £400–£900 price, that's a healthy margin for a day's work — provided you've priced the spoil disposal and any awkward access into the job.

Labour and Time

Most small shed bases are a one-day job for one or two people. A grid or paving base on level, easy ground can be done by a single experienced operator in a day; a concrete base is more comfortable with two so one can mix or barrow while the other lays and tamps. Larger summerhouses, sloping sites or log cabins needing a thicker reinforced slab can run to a day and a half or two days, sometimes split across visits to let the concrete cure before the building goes up. Price your labour at your normal day rate and don't let the small footprint fool you into undercharging — the digging and disposal are the same hard graft as a bigger job.

What Adds Cost

The base price assumes reasonable conditions. Several factors push the price up, and you need to spot them at the site visit rather than discover them when you turn up to start:

• Sloping or uneven ground: Extra excavation on the high side and built-up sub-base on the low side, plus shuttering to retain it. A slope can easily add half a day.
• Soft or clay ground: Needs digging out deeper and a thicker sub-base to get a stable foundation. Waterlogged clay is the worst offender.
• Poor access: If concrete and materials have to be barrowed through a house, a narrow side gate or a long garden, your time goes up sharply. No driveway access for a ready-mix wagon means hand-balling everything.
• Removing an old base: Breaking out and disposing of an existing concrete or slab base is a job in itself — price the breaking, the skip and the muck-away.
• Larger log cabins: Need a bigger, thicker, often reinforced slab, which means more dig, more concrete and more time.
• Distance to the pour: The further the concrete has to travel from the wagon or mixer to the base, the more barrowing and the more labour.

Log Cabin and Summerhouse Bases

Log cabins and large summerhouses are a different proposition to a basic shed. They're much heavier, so they need a bigger, thicker and usually reinforced concrete base — commonly a 100–150mm slab with steel mesh on a well-compacted sub-base. Crucially, the base must be slightly larger than the building footprint, not smaller, so the cabin sits fully supported with the walls landing on solid concrete and a small overhang of base all round.

That overhang isn't just for support — it keeps rainwater running off the building from soaking the timber at the foot of the walls. Get the size, thickness and reinforcement right and you can charge accordingly: log cabin bases frequently run £700–£1,500+ depending on size and ground. These are exactly the jobs where a careful site survey and a properly built slab pay for themselves.

Drainage and Finishing

A good base manages water. It should sit slightly proud of the surrounding ground so surface water runs away from it rather than pooling underneath the building. Build in a gentle fall — a few millimetres per metre — so any water on the surface drains off. Leave a small gap between the base and the building's cladding so the timber isn't sitting in trapped damp, and keep soil, bark and planting away from the foot of the walls. A base that traps moisture against the building defeats the whole point of building it properly. Finishing well here is what separates a base that lasts twenty years from one that causes a rot complaint in three.

A Quick Note on Building Regs

Most domestic sheds and garden buildings fall under permitted development and don't require building regulations approval or planning permission, provided they stay within the usual size, height and use limits — broadly single-storey, not too tall, not covering too much of the garden, and not used as living or sleeping accommodation. Larger buildings, anything close to a boundary, anything used as habitable space, or properties in conservation areas can be a different story. It's not your job to sign off planning, but it's worth a quick word with the customer to check the building is within permitted development — and to suggest they confirm with the local authority if there's any doubt.

Quoting Tips

Shed base quotes go wrong when they're priced over the phone off a customer's description. A short site visit removes nearly all the risk. Before you commit a price, check the following:

• View the site: Always see the actual spot. Photos and descriptions hide slopes, soft ground and access problems.
• Check ground type and slope: Probe for soft or clay ground and gauge the fall across the base. This drives your dig depth and build-up.
• Measure and add the overhang: Build the base slightly larger than the building footprint. Get the building's dimensions from the customer's order and size the base accordingly.
• Identify access for materials: Can a ready-mix wagon get near, or is everything barrowed? Access is the biggest hidden cost on base jobs.
• Price spoil disposal: Work out how much you're digging out and where it goes. Skip or grab-away has to be in the number.
• Fixed price, clearly specified: Quote a fixed price stating the base type, dimensions and thickness in writing, so there's no argument about what was included.
• Upsell the better base: Show the customer why concrete or slabs protect their warranty and their building versus the cheapest option. Most will happily pay the difference once it's explained.

Quick Reference: Shed Base Prices UK 2026