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Concrete Slab Cost Calculator 2026 | UK Slab Price Estimator

Concrete Slab Cost Calculator 2026

Calculate Floor Slab Costs Instantly

Complete UK Slab Material and Labour Estimator

Concrete floor slabs are fundamental construction elements for residential, commercial, and industrial buildings. Our concrete slab cost calculator provides accurate estimates for materials, labour, and total project costs based on 2026 UK pricing. Calculate concrete volume, reinforcement requirements, sub-base materials, and installation costs for any slab dimension.

Typical UK concrete slab costs range from £65-£95 per square metre for basic ground floor slabs including materials and labour. Prices vary by slab thickness (100-300mm), concrete grade (C25-C35), reinforcement type, and ground conditions. Our calculator follows Building Regulations standards for accurate cost estimation.

📐 Concrete Slab Calculator

Calculate complete slab costs including concrete, reinforcement, and labour

Slab Dimensions

Materials Specification

Sub-base & Labour

Concrete Slab Cost Guide UK 2026

Understanding concrete slab costs involves multiple components including excavation, sub-base preparation, DPM installation, insulation, reinforcement, concrete supply, and finishing labour. Our comprehensive guide breaks down all cost elements for accurate budgeting based on RICS standards.

Complete Slab Costs per Square Metre

Slab Type Thickness Cost per m² Typical Application
Basic Ground Slab 100mm £55 - £70 Sheds, garages, light storage
Standard Residential 125-150mm £65 - £85 Houses, domestic extensions
Insulated Ground Floor 150mm + 100mm insulation £85 - £110 New build homes (Building Regs)
Commercial Floor 175-200mm £95 - £125 Retail units, offices, workshops
Industrial Heavy Duty 200-250mm £120 - £160 Warehouses, factories, loading areas
Raft Foundation 250-300mm £145 - £195 Poor ground, structural foundation
Suspended Slab 150-200mm £110 - £150 First floor, over voids, beam & block
Polished Concrete Floor 150mm + polishing £130 - £180 Modern homes, showrooms, retail

Basic Ground Slab

Thickness 100mm
Cost £55 - £70/m²
Use Garages, storage

Standard Residential

Thickness 125-150mm
Cost £65 - £85/m²
Use House extensions

Insulated Ground Floor

Thickness 150mm + insulation
Cost £85 - £110/m²
Use New build homes

Industrial Heavy Duty

Thickness 200-250mm
Cost £120 - £160/m²
Use Warehouses, factories

Material Cost Breakdown

Concrete slab construction requires multiple materials working together to create a durable, stable floor system. Each component serves a specific purpose and contributes to overall project costs.

Ready-Mix Concrete

C20/25: £95-£105/m³ (light duty only)

C25/30: £105-£115/m³ (standard residential)

C30/37: £115-£130/m³ (recommended for floors)

C35/45: £130-£145/m³ (commercial/industrial)

150mm slab: 0.15m³ per m² (approx)

Wastage: Add 5-7% for standard projects

Reinforcement Mesh

A142 (6mm @ 200mm): £3.20-£3.80/m²

A193 (7mm @ 200mm): £4.00-£4.50/m²

A252 (8mm @ 200mm): £4.80-£5.40/m²

A393 (10mm @ 200mm): £6.50-£7.20/m²

Mesh size: 4.8m × 2.4m sheets typical

Overlap: 300-400mm lap at joints

DPM Membrane

Basic 300 gauge: £0.70-£0.90/m² + £0.10 tape

Standard 1200 gauge: £2.00-£2.50/m²

Reinforced 1200 gauge: £3.50-£4.50/m²

Gas membrane: £4.50-£6.00/m² (radon areas)

Overlap: 150mm minimum, sealed with tape

Wall upstand: 150mm above finished floor level

Floor Insulation

50mm PIR: £11-£13/m² (U-value 0.44)

75mm PIR: £15-£18/m² (U-value 0.30)

100mm PIR: £19-£22/m² (U-value 0.22)

150mm PIR: £27-£30/m² (U-value 0.15)

Building Regs: U-value ≤0.22 W/m²K (2022)

Placement: Above DPM, below concrete

Sub-base Materials

MOT Type 1: £22-£28/tonne delivered

150mm depth: Approx 2.2 tonnes/10m²

200mm depth: Approx 3.0 tonnes/10m²

Compaction: Mechanical plate compactor

Sand blinding: £35-£50/tonne (50mm layer)

Membrane sand: 25-30kg/m² for protection

Additional Materials

Edge formwork: £3-£6 per linear metre

Expansion joints: £8-£12/m (foam + sealant)

Spacers/chairs: £10-£18 per 100 units

Curing compound: £30-£45 per 5L

Concrete pump: £250-£450 (if needed)

Power float hire: £50-£80/day

Labour Costs and Installation Time

Labour represents a significant portion of concrete slab costs, typically 30-40% of total project expense. Installation time depends on slab area, ground conditions, access constraints, and finishing requirements.

✅ Labour Rates UK 2026:

  • General Labourer: £120-£180 per day (groundwork, materials handling)
  • Groundworker: £180-£250 per day (excavation, sub-base, formwork)
  • Concreter: £200-£280 per day (screeding, finishing, power floating)
  • Gang Rate (3 workers): £600-£850 per day (complete team for larger projects)
  • Regional Premium: London/Southeast +30-40%, Scotland +15-20%
  • Weekend Work: +50% rate typical for Saturday/Sunday work

Installation Timeline

Project Stage Small Slab (30m²) Medium Slab (80m²) Large Slab (150m²)
Excavation & Levelling 1 day 1-2 days 2-3 days
Sub-base Installation 1 day 1-2 days 2-3 days
DPM, Insulation, Mesh 0.5 day 1 day 1-2 days
Edge Formwork 0.5 day 1 day 1-1.5 days
Concrete Pour & Finish 1 day 1 day 1-2 days
Curing Period 7 days 7 days 7 days
Total Active Work 4 days 5-7 days 7-11 days
Project Duration 11 days 12-14 days 14-18 days

Small Slab (30m²)

Active Work 4 days
Including Curing 11 days total

Medium Slab (80m²)

Active Work 5-7 days
Including Curing 12-14 days total

Large Slab (150m²)

Active Work 7-11 days
Including Curing 14-18 days total

Slab Thickness Requirements

Correct slab thickness is critical for structural performance and longevity. Under-specification leads to cracking and failure; over-specification wastes money. Follow NHBC standards for residential slabs.

Thickness Selection Guide

  • 100mm: Minimum for light-duty applications only (sheds, garden buildings, pedestrian paths). Not suitable for vehicle traffic or heavy loads. Use C25/30 minimum with A142 mesh.
  • 125mm: Adequate for domestic garages (cars only), light workshops, storage areas with moderate foot traffic. C25/30 concrete with A193 mesh recommended.
  • 150mm: Standard residential ground floor slab thickness for houses, extensions, conservatories. Suitable for normal domestic loading. C30/37 with A193 mesh standard specification.
  • 175mm: Commercial applications including retail units, offices, light industrial units. Handles forklift traffic and moderate storage loads. C30/37 with A252 mesh minimum.
  • 200mm: Heavy-duty industrial floors, warehouses, loading bays, agricultural buildings. Withstands heavy vehicle traffic and racking systems. C35/45 with A393 mesh recommended.
  • 250mm+: Extra heavy-duty applications including heavy machinery, crane loads, multi-storey car parks. Requires full structural design. Specialist reinforcement beyond standard mesh.

⚠️ Common Slab Thickness Mistakes:

  • Under-thickness for vehicles: 100mm slabs crack under car weight; minimum 125mm for cars, 150mm for vans/trucks
  • No edge thickening: Perimeter needs 300mm depth or separate strip foundation for load-bearing walls
  • Suspended slab confusion: Suspended slabs need structural calculation; thickness depends on span not floor use
  • Ignoring ground conditions: Poor ground (clay, made ground) requires raft foundation or piled solution, not standard slab
  • Reinforcement omission: All structural slabs require mesh; plain concrete cracks excessively

Ground Floor Slab Construction Process

Proper construction sequence ensures slab durability and performance. Each stage must be completed correctly before proceeding to the next.

1. Site Preparation

Excavation: Remove topsoil, organic matter to formation level

Depth: Slab thickness + sub-base + blinding (typically 350-400mm total)

Level: Check with laser level or string lines

Services: Install drainage, utilities before slab pour

Ground Treatment: Compact subgrade to 95% MDD

2. Sub-base Installation

Material: MOT Type 1 or DOT Type 1 hardcore

Thickness: 150mm minimum, 200mm for poor ground

Compaction: Mechanical plate compactor in 100mm layers

Level Check: ±10mm tolerance across slab area

Blinding: 50mm sharp sand for smooth DPM surface

3. DPM & Insulation

DPM First: Lay damp proof membrane on blinding sand

Overlap: 150mm minimum, sealed with DPM tape

Wall Upstand: Turn up walls 150mm above finished level

Insulation: Rigid PIR boards laid over DPM (if specified)

Protection: Cover insulation immediately to prevent damage

4. Reinforcement Placement

Mesh Type: A193 minimum for residential, A252 commercial

Position: Mid-depth of slab (on spacers/chairs 70-75mm high)

Overlap: 400mm or 2 squares minimum at joints

Edge Distance: 50mm from all edges and openings

Secure: Tie laps with wire; ensure mesh doesn't sag during pour

5. Concrete Pour

Weather: Avoid pouring in rain, frost, or temperatures below 3°C

Pour Method: Direct chute, pump, or wheelbarrow (small areas)

Compaction: Vibrate or tamp to eliminate voids

Screeding: Level with timber screed board or power screed

Continuous: Complete pour without long breaks (cold joints)

6. Finishing & Curing

Tamping: Initial compaction with beam or power float

Trowelling: Steel trowel finish once surface water evaporates

Power Floating: Optional smooth finish with machine

Curing: Apply curing compound or cover with polythene

Protection: No foot traffic 24 hours, loading after 7 days

Building Regulations Compliance

Ground floor slabs in England and Wales must comply with Building Regulations Approved Documents. Key requirements include thermal performance, damp proofing, and structural adequacy.

📋 Key Building Regulations Requirements:

  • Part A (Structure): Slab must support dead and live loads safely; structural calculations required for suspended slabs or unusual conditions
  • Part C (Resistance to Moisture): DPM minimum 300 micron (1200 micron recommended), continuous with wall DPC, lapped and sealed joints
  • Part L (Conservation of Fuel & Power): U-value ≤0.22 W/m²K for ground floors (typically requires 100-150mm insulation)
  • Part M (Access): Level thresholds for accessible entrances; maximum 15mm upstand where DPM meets doors
  • Radon Protection: Radon sumps and membranes required in affected areas (check UKRadon maps)

Concrete Slab Calculator FAQs

How much does a concrete slab cost per square metre?
A standard 150mm residential concrete slab costs £65-£85 per m² including all materials and labour (sub-base, DPM, mesh, concrete, finishing). Basic 100mm garage slabs cost £55-£70/m², while insulated ground floors with 100mm PIR cost £85-£110/m². Commercial 200mm slabs range £95-£125/m², and industrial heavy-duty slabs cost £120-£160/m².
What thickness concrete slab do I need for a house?
Standard residential ground floor slabs are 150mm thick using C30/37 concrete with A193 mesh reinforcement. This suits all normal domestic loading. Garage slabs can be 125mm for cars only. Extensions and conservatories typically use 150mm. Always follow structural engineer specifications for suspended slabs or unusual conditions.
Do I need insulation in my ground floor slab?
Yes, for habitable buildings (houses, extensions). Building Regulations Part L requires U-value ≤0.22 W/m²K, achieved with 100mm PIR insulation (or 75mm with improved products). Unheated garages and storage buildings don't legally require insulation but benefit from reduced condensation. Insulation adds £19-£22/m² but saves heating costs long-term.
Can I lay concrete directly on soil?
No, never pour concrete directly on soil or clay. Always install sub-base (150mm MOT Type 1 minimum) for load distribution and drainage, plus sand blinding layer (50mm) for smooth surface. Without sub-base, ground movement causes severe cracking. Also requires DPM (damp proof membrane) over sub-base to prevent moisture rising into slab.
What reinforcement mesh do I need?
A193 mesh (7mm bars @ 200mm centers) is standard for residential slabs. A142 acceptable for very light duty (garden rooms). A252 needed for commercial use with forklifts or heavy storage. A393 for industrial heavy-duty floors. Mesh must sit at mid-depth of slab on proper spacers (70-75mm high for 150mm slab).
How long before I can walk on new concrete?
Wait 24 hours minimum before walking on new concrete, 3-5 days for light equipment, and 7 days before normal loading (furniture, vehicles). Concrete reaches approximately 70% strength at 7 days and full strength at 28 days. Cold weather extends curing time. Protect from frost, rain, and direct sunlight during first week.
Do I need Building Control approval for a concrete slab?
Yes, for all habitable buildings and extensions. Submit Building Notice or Full Plans application showing slab specification, insulation U-value calculations, and DPM details. Building Control inspects foundation excavation, DPM/insulation installation before concrete pour, and again after completion. Exempt for some detached garages/sheds under 30m² (check specifics).
What happens if I don't use DPM?
Without DPM, ground moisture rises through concrete via capillary action causing damp floors, mold growth, floor covering failure (lifting tiles, rotting wood), and failed Building Regulations inspection. DPM is mandatory for all habitable buildings and strongly recommended for garages. Use minimum 1200 gauge polyethylene, properly lapped (150mm) and sealed with tape.
How do I calculate concrete volume for a slab?
Volume (m³) = Length (m) × Width (m) × Thickness (m). Example: 10m × 8m × 0.15m = 12m³. Always add 5-7% wastage, so order 12.6-12.8m³. For irregular shapes, break into rectangles and sum. Use our calculator above for automatic calculations including all materials needed.
Can I pour a large slab in sections?
Yes, use construction joints (vertical division) for large areas. Install temporary formwork, pour first section, remove formwork after 2-3 days, pour adjacent section. Ensure good key between sections (roughen edge or use bonding agent). For domestic slabs, aim to pour in one session where possible. Cold joints (unplanned breaks) create weakness and should be avoided.

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