Garage Base Costs | ConcreteMaths.com

Estimate the cost of a single, double or prefab garage base in the UK with concrete volume, slab thickness, sub-base, reinforcement, labour, delivery and VAT-style budget ranges — updated for 2026 pricing and practical UK site conditions.

Enter the planned garage base size, slab thickness and specification. The guide estimates concrete volume, ready-mix cost, sub-base allowance, labour range and a practical installed budget. It is designed for early pricing, supplier quotes and self-build planning, not structural design.

18.00 m²

2.48 m³

£300–£420

£540–£810

£720–£1,080

Do Not Price a Garage Base from Concrete Volume Alone

The concrete is only one part of the bill. A proper garage base normally includes excavation, waste removal, compacted granular sub-base, shuttering, damp proof membrane, possible reinforcement, concrete supply, placing, levelling, finishing, curing and access management. A cheap quote that ignores ground preparation can become expensive later if the slab cracks, settles or sits too high for the garage door threshold.

Garage Base Type: Small prefab garage base; Typical Size: 2.7m × 5.0m = 13.5m²; Concrete Volume*: 1.5–2.2m³; Typical 2026 Installed Cost: £1,250–£2,250; Best For: Compact prefab concrete garage, light car, garden storage
Garage Base Type: Single garage base; Typical Size: 3.0m × 6.0m = 18m²; Concrete Volume*: 2.0–3.0m³; Typical 2026 Installed Cost: £1,700–£3,000; Best For: Most domestic single garages and sectional garages
Garage Base Type: Double garage base; Typical Size: 6.0m × 6.0m = 36m²; Concrete Volume*: 4.0–6.0m³; Typical 2026 Installed Cost: £3,400–£6,000; Best For: Two-car garage, workshop, larger detached outbuilding
Garage Base Type: Reinforced garage/workshop slab; Typical Size: 25–50m²; Concrete Volume*: 3.5–8.5m³; Typical 2026 Installed Cost: £130–£190 per m²; Best For: Heavier vehicles, lifts, machinery, motorcycles, resources
Garage Base Type: Difficult access garage base; Typical Size: Any size; Concrete Volume*: Varies; Typical 2026 Installed Cost: +£300–£1,200 extra; Best For: Long barrow run, pump hire, narrow driveway, restricted delivery

*Concrete volume assumes 100–150mm slab thickness plus a normal waste allowance. Final slab design depends on ground conditions, vehicle loading, drainage and garage supplier requirements.

A garage base looks simple from the outside: dig out the ground, add hardcore, pour concrete and let it cure. In practice, the price can vary widely because the base has to do several jobs at the same time. It must support the weight of the garage, resist vehicle loads, stay level enough for the garage door to close, keep water away from the slab, avoid damp problems and provide a stable platform for fixings or wall panels. That is why the cheapest “concrete only” price is rarely the true installed cost of a garage base.

For 2026 budgeting, a typical UK garage base commonly falls around£95–£160 per square metrewhen excavation, sub-base, shuttering, membrane, concrete, labour and basic finishing are included. Small bases can be more expensive per square metre because delivery, mobilisation and labour setup costs are spread over fewer metres. Larger bases usually get better concrete efficiency but may require more labour, reinforcement, drainage details or Building Control involvement.

The most reliable way to budget is to separate the base into layers: ground preparation, sub-base, membrane, reinforcement, concrete and finishing. A 100mm slab may look cheaper at first, but a garage used for a vehicle, van, home gym, workshop bench or storage racking often benefits from 125mm or 150mm. The extra concrete volume is usually a modest part of the total price, while the improvement in robustness can be valuable over the life of the garage.

What Is Included in a Proper Garage Base Quote?

A good quote should describe more than “concrete slab”. It should explain the base size, finished level, excavation depth, sub-base thickness, membrane, reinforcement, concrete grade, surface finish, curing approach and waste removal. If the quote does not mention these items, you may be comparing an incomplete allowance against a proper installed base.

1. Excavation and spoil removal

Grass, topsoil, soft ground and old paving normally need to be removed. Disposal costs rise if spoil must be taken off site rather than reused elsewhere in the garden.

2. Compacted MOT Type 1 sub-base

A garage slab is only as reliable as the ground below it. A compacted granular layer spreads loads and reduces settlement risk.

3. Damp proof membrane

A DPM helps reduce moisture rising through the concrete. This matters for stored resources, vehicles, gym equipment and timber wall plates.

4. Concrete, placing and finish

Ready-mix concrete must be discharged, placed, levelled and finished while workable. Poor access can add pumping or barrowing labour.

When checking a quote, ask whether VAT is included, whether the concrete supplier’s short-load or delivery fees are included, who pays for any extra concrete ordered on the day and whether the price assumes direct chute discharge from the mixer truck. A garage behind a house or down a narrow side passage can be more expensive than the same base at the front of a driveway because the concrete must be moved by barrow, dumper or pump.

Cost Item: Excavation; Typical 2026 Range: £20–£45 per m²; What It Covers: Digging out topsoil, old slab, soft spots and levelling formation; Cost Notes: Higher if access is tight or old concrete must be broken out
Cost Item: Waste removal; Typical 2026 Range: £150–£600+; What It Covers: Skip, grab lorry, spoil disposal or rubble removal; Cost Notes: Old concrete, clay and contaminated spoil can increase cost
Cost Item: MOT Type 1 sub-base; Typical 2026 Range: £25–£55 per m²; What It Covers: Supply, spread and compact granular hardcore layer; Cost Notes: 100–150mm compacted thickness is common for domestic bases
Cost Item: DPM and shuttering; Typical 2026 Range: £8–£22 per m²; What It Covers: Membrane, timber formwork, levels and edge restraint; Cost Notes: More for complex shapes, steps, thresholds or thickened edges
Cost Item: Concrete supply; Typical 2026 Range: £105–£150 per m³; What It Covers: Ready-mix concrete, commonly C25/30 or C30/37 for garage slabs; Cost Notes: Short loads, delivery and admixtures can add to the headline rate
Cost Item: Mesh reinforcement; Typical 2026 Range: £12–£35 per m²; What It Covers: A142/A193 style mesh, spacers and fixing where specified; Cost Notes: Useful for workshops, heavier loads and crack-control strategies
Cost Item: Labour and finishing; Typical 2026 Range: £35–£75 per m²; What It Covers: Placing, screeding, tamping, edge work, curing and tidying; Cost Notes: Rises with poor access, hot weather, pump use or tight schedules

How Thick Should a Garage Base Be?

For a domestic garage floor,100mmis often treated as the practical minimum slab thickness for light-duty use. Many UK installers prefer125mmfor a more robust everyday garage base, while150mmis commonly selected when the garage will hold a heavier car, van, motorcycles, racking, gym kit or workshop equipment. Some engineered slabs, commercial use cases or poor ground conditions can require thicker concrete, mesh, thickened edges or separate foundations.

Thickness should not be selected in isolation. A 150mm slab placed over soft, uncompacted ground can still fail. A well-prepared 125mm slab over a properly compacted sub-base may perform far better than a thicker slab poured over weak ground. The ground should be excavated to a stable formation, soft spots should be removed, and the granular sub-base should be compacted in layers. The slab level should also work with drainage, garage door clearance and surrounding paths or driveway levels.

Ready-mix suppliers and manufacturers often publish practical guidance for concrete garage floors. For example, major UK concrete guidance commonly refers to a minimum around 100mm for standard domestic use, with thicker slabs such as 150–200mm where heavier vehicles or more demanding use are expected. Always follow your garage supplier’s base drawing where one is provided, because sectional and prefab garages often need exact base dimensions and edge details.

100mm slab

Budget domestic garage base where ground is good, loading is light and the garage is not used as a heavy workshop.

125mm slab

Good all-round choice for a single or double domestic garage with a normal car and occasional storage.

150mm slab

Common upgrade for heavier vehicles, vans, larger double garages, resource storage and workshop loads.

Engineered slab

Required where loads, ground conditions, retaining edges or structural requirements go beyond standard domestic assumptions.

Best Concrete Grade for a Garage Base

Most domestic garage bases are specified aroundC25/30, although C20/25 may be seen on light-duty non-structural slabs and C30/37 is often chosen for a stronger or more durable garage floor. The grade is only one part of the specification. Consistence, aggregate size, exposure class, fibres or mesh, curing and finish all affect the final performance of the slab.

The UK normally uses BS EN 206 with the UK complementary standard BS 8500 for specifying concrete. A concrete grade such as C25/30 refers to characteristic compressive strength, with the first number referring to cylinder strength and the second to cube strength. Homeowners do not need to memorise the standard, but the quote should still state the concrete grade clearly. “Concrete for garage base” is too vague if the base is important, supports a vehicle or will be used for a workshop.

If the slab will be exposed to de-icing salts, frequent wetting, freeze-thaw conditions or heavy wear, ask the supplier or designer whether a durability specification is required. A garage attached to a house, a sloping driveway, poor drainage or a high water table can change the right solution. Stronger concrete alone does not fix poor drainage or inadequate sub-base preparation.

Concrete Grade: C20/25; Use for Garage Base?: Sometimes; Typical Role: Light-duty domestic slabs, paths, simple bases where loading is low; 2026 Cost Impact: Lower concrete cost, but may not be ideal for vehicle-heavy use
Concrete Grade: C25/30; Use for Garage Base?: Recommended Standard; Typical Role: Common domestic garage slabs, single garages, double garages and prefab bases; 2026 Cost Impact: Balanced cost and strength for most home garage projects
Concrete Grade: C30/37; Use for Garage Base?: Stronger Option; Typical Role: Heavier vehicles, workshops, reinforced slabs, higher durability preference; 2026 Cost Impact: Usually a modest extra cost per m³ compared with C25/30
Concrete Grade: C35/45+; Use for Garage Base?: Specialist; Typical Role: Engineered or commercial slabs where specified by a designer; 2026 Cost Impact: Higher cement content and stricter specification increase cost

Single Garage Base Cost Example

A common single garage base is about 3m wide by 6m long, giving a floor area of 18m². At 125mm thick, the concrete volume is 2.25m³ before waste and about 2.48m³ with a 10% allowance. The ready-mix concrete itself may only represent a few hundred pounds of the project, but the installed base includes excavation, stone, compaction, shuttering, DPM, labour, finishing and waste handling.

For 2026 planning, a straightforward single garage base may sit around£1,700–£3,000. The lower end assumes clear access, no old slab removal, good ground, direct concrete discharge and a simple rectangular base. The higher end allows for more difficult access, higher labour time, more sub-base, mesh reinforcement, concrete delivery charges or local price pressure.

If you are ordering a prefab garage, check whether the supplier wants the base to be exactly the garage footprint, slightly larger, or formed with a rebated edge. Some prefab garages require bolt-down fixings and precise level tolerances. The base should normally be square, flat, properly cured and set at a level that does not channel water under the garage door.

Double Garage Base Cost Example

A typical double garage base might be 6m × 6m, or 36m². At 125mm thick, that is 4.5m³ before waste and roughly 4.95m³ with a 10% allowance. At 150mm thick, it becomes about 5.94m³ with waste. That difference matters because it can move the order closer to a part-load threshold or a full ready-mix delivery.

For 2026, a double garage base commonly budgets at about£3,400–£6,000, depending on specification. A double garage is not just twice the concrete of a single; it often needs more careful screeding, more joints or crack-control planning, more sub-base compaction and more attention to drainage. If the slab will be used as a workshop, gym or storage area, many homeowners upgrade to 150mm and consider mesh reinforcement.

Large slabs should be planned with movement and crack control in mind. Concrete shrinks as it cures, so saw cuts, construction joints or reinforcement may be used to manage where cracks form. The right approach depends on slab size, shape, loading and finish expectations. A neat garage base does not have to look polished, but it should drain correctly, remain stable and provide a durable wearing surface for everyday use.

Planning Permission, Building Regulations and Structural Checks

A garage base may seem like landscaping, but it can sit inside a wider building project. Detached garages, attached garages, larger outbuildings and garages near boundaries can trigger planning or Building Regulations questions. Rules differ between England, Wales, Scotland and Northern Ireland, and local circumstances such as conservation areas, listed buildings, drainage restrictions and shared access can change what is required.

The safest approach is to check official guidance before work starts. In England,Approved Document Acovers structural safety principles for buildings, while thePlanning Portal foundation guidanceexplains that foundations should transmit loads safely to the ground. For concrete specification, the relevant standards background includesBS EN 206and the UK complementary BS 8500 guidance discussed by the Concrete Centre.

For a simple domestic prefab garage, the supplier may provide a base drawing. For an attached garage, retaining wall, poor ground, sloping site, tree influence or a slab carrying heavier machinery, a structural engineer or Building Control advice may be needed. Paying for the right base specification is cheaper than cutting out and replacing a cracked or settled slab later.

What Makes a Garage Base More Expensive?

The headline cost per square metre is useful, but it hides the items that can push a quote higher. Site access is one of the biggest. If a concrete truck can reverse close to the base and discharge by chute, placing is faster. If concrete must be barrowed 30 metres through a side gate, labour and risk increase. If a pump is required, the concrete placement can be faster but the pump has a separate charge and may need extra setup space.

Ground conditions are another major variable. Soft clay, filled ground, tree roots, old drains, buried rubble or a sloping site can increase excavation depth and sub-base thickness. Where water sits on the surface, drainage improvements may be needed before pouring the slab. A base that is too low can flood; a base that is too high can create a trip hazard, block the garage door opening or breach surrounding levels.

The chosen garage type also matters. A lightweight timber garage may have different requirements from a sectional concrete garage. A steel-framed garage may need pad details or anchor bolts. A garage that will later receive insulation, a resin coating, tiles or a workshop floor may need a better finish and better moisture control than a basic storage garage.

Old slab removal:breaking, loading and disposal can add hundreds of pounds.
Long concrete run:barrowing or pumping increases labour and placement cost.
Short-load concrete:small orders may attract part-load charges.
Reinforcement:mesh, spacers and extra labour increase the price but can improve crack control.
Drainage:gullies, channels, falls or soakaway work may be required where water collects.
Regional costs:London and the South East often carry higher labour, delivery and disposal rates.

Garage Base Build-Up: From Ground to Finished Slab

A typical garage base build-up begins with excavation to a suitable depth. This depth must allow for the finished concrete level, slab thickness, sub-base thickness and sometimes a sand blinding layer or membrane protection. The ground should be firm and stable before stone is placed. If the ground is soft or disturbed, the weak material should be removed and replaced or the base redesigned.

The sub-base is normally compacted MOT Type 1 or similar granular material. It should be placed in layers and compacted with a plate compactor or roller. The damp proof membrane is then laid with appropriate laps and protection from punctures. Shuttering forms the slab edges and sets the final level. Reinforcement mesh, where used, should be supported on spacers so it sits in the right zone of the concrete rather than lying directly on the membrane.

Concrete should be ordered with enough time to place and finish it while workable. In hot weather, delays can be costly because concrete stiffens faster. The team should be ready before the truck arrives. After placing, the slab should be finished to the required texture and then protected while it cures. Avoid loading the slab too early, and check the garage supplier’s curing requirements before installing the garage.

How to Get a Better Garage Base Quote

Before asking for prices, measure the base accurately and decide whether the size is internal garage size, external garage size or the supplier’s required concrete pad size. A common mistake is pricing a base that is slightly too small for the garage walls or too narrow for door tracks and fixings. If your garage supplier provides drawings, send those drawings to the contractor.

Ask every contractor to price the same specification. That makes quotes easier to compare and reduces the risk of hidden extras. A useful quote request might say: “Please price a 6m × 3m garage base, 125mm C25/30 concrete, 100–150mm compacted MOT Type 1 sub-base, DPM, shuttering, waste removal and tamped finish. Please include access assumptions and state whether VAT, concrete delivery and short-load charges are included.”

It is also wise to ask how long before the garage can be installed. Concrete gains strength over time, and while light foot traffic may be possible earlier, heavy loading and fixing a garage should follow the installer’s curing advice. For a neat job, confirm who is responsible for protecting the slab from rain, frost, hot sun, pets, footprints and accidental vehicle traffic during curing.

Common Garage Base Mistakes That Increase Long-Term Cost

The most expensive garage base problems are usually not caused by choosing C25 instead of C30. They are caused by poor setting-out, weak ground preparation, bad drainage or rushing the pour. A base that is too small may leave wall panels overhanging the slab. A base that is not square can make garage installation difficult. A slab that is too high can send rainwater toward the building, while a slab that is too low can collect water at the garage door.

Another common mistake is forgetting the threshold detail. Garage doors, side doors and ramps need finished levels that work with the driveway and surrounding ground. If you plan to add a resin floor, tiles, insulation or a timber floating floor later, allow for the extra build-up before concrete is poured. Correcting levels after the garage is built is much harder than setting them correctly at the start.

Finally, do not remove curing time from the programme. Concrete may look hard after a day or two, but it continues gaining strength. Protecting the slab from rapid drying, frost, standing water and early heavy loads helps reduce cracking and surface weakness. A careful curing plan costs very little compared with the cost of repairing a damaged garage floor.

£95–£160 per m²

£1,700–£3,000

£3,400–£6,000

100mm

125mm

150mm

C25/30

C30/37