Types of Concrete in UK

Compare the main UK concrete types, mix designations, strength classes, exposure requirements and best-use cases for foundations, slabs, driveways, floors, reinforced concrete and specialist projects in 2026.

Types of Concrete in the UK — What the Names Really Mean

Concrete typecan mean several different things in the UK. A builder might say “foundation mix”, a ready-mix supplier might quoteGEN3orRC30, an engineer might specifyC32/40 XF3 DC-2 S3, and a DIY bag might simply say “multi-purpose concrete”. All of these descriptions refer to concrete, but they do not describe the same level of performance, durability or responsibility.

For 2026 UK construction, the most reliable way to understand concrete is to separate it into four layers: theuseof the concrete, thestrength class, thedurability exposure, and thespecification route. A garden path may only need a simple general concrete. A reinforced retaining wall needs a structural concrete with cover, reinforcement, exposure and crack-control considerations. A driveway exposed to frost and winter de-icing salts needs a mix designed for freeze-thaw and salt resistance rather than just a convenient compressive strength.

UK concrete specification is normally aligned withBS 8500andBS EN 206. BS 8500 is the UK complementary standard, providing UK national rules, designation systems, exposure class guidance and practical specification routes. It was substantially updated in 2023, with the 2026 market now strongly focused on compliant lower-carbon binders, improved durability selection and better ordering clarity.

2026 Practical Rule

Do not select concrete by strength alone. For external slabs, foundations, reinforced elements and chemically exposed areas, the exposure class, cement type, maximum water/cement ratio, minimum cement content, air entrainment and cover requirements may matter as much as the headline C-class strength.

Designated Concrete

Predefined BS 8500 mix names such as GEN, RC, FND and PAV. These are common for domestic and routine work because the supplier controls the detailed recipe.

Designed Concrete

Concrete specified by required strength, exposure, chloride class, consistence, aggregate size and other performance criteria. Used for engineered and durability-critical work.

Standardised Prescribed Concrete

Traditional ST mixes where the composition is prescribed rather than performance-designed. Useful for simple non-structural applications where appropriate.

Why UK Concrete Types Are Confusing

The same job can be described in different ways by different people. A “garage base mix” might be sold as GEN3, C20/25, RC25, or a local supplier’s own “garage slab mix”. A “driveway mix” might be adequate for a footpath but unsuitable for vehicles and winter salt. This is why a good concrete guide should not only list mix names but also explain the conditions each mix is designed to handle.

In simple terms, concrete becomes more demanding as load, exposure and risk increase. A light domestic slab may be low risk. A suspended reinforced slab is higher risk. A concrete yard exposed to manure, slurry, freeze-thaw and vehicle abrasion is a specialist durability problem. A coastal retaining wall is not just “strong concrete”; it needs chloride resistance, cover and crack-control design.

BS 8500 Designated Concrete Types in the UK

Designated concreteis widely used across UK housebuilding, small commercial projects and routine civil work because it gives a simple name to a pre-defined performance category. The buyer specifies the designation, and the producer supplies concrete that meets the standard requirements for that designation. This reduces ambiguity for common work, but it does not remove the need to select the right designation for the project environment.

• Concrete Family: GEN — General Concrete; Typical UK Uses: Blinding, kerb backing, domestic strip footings, shed bases, simple slabs; Common Designations: GEN0, GEN1, GEN2, GEN3; Typical Notes: ✓ Best for routine domestic work
• Concrete Family: RC — Reinforced Concrete; Typical UK Uses: Reinforced slabs, beams, walls, foundations, retaining structures; Common Designations: RC20/25, RC25/30, RC30/37, RC35/45, RC40/50; Typical Notes: Requires reinforcement and cover design
• Concrete Family: PAV — Paving Concrete; Typical UK Uses: Driveways, external slabs, yards, pavements and vehicle areas; Common Designations: PAV1, PAV2; Typical Notes: Select for frost and de-icing salt risk
• Concrete Family: FND — Foundation Concrete; Typical UK Uses: Foundations in ground where sulfate resistance must be considered; Common Designations: FND2, FND3, FND4, FND4Z; Typical Notes: Driven by ground investigation
• Concrete Family: DRC / Proprietary Mixes; Typical UK Uses: High-performance, waterproof, fibre, self-compacting or low-carbon concretes; Common Designations: Supplier-specific; Typical Notes: Confirm performance data

GEN Concrete Types

GEN concreteis the everyday general concrete family used for lower-risk domestic and building tasks. GEN0 and GEN1 are commonly used for blinding, kerb backing and non-structural fill. GEN2 and GEN3 are used where slightly greater strength or durability is required, such as domestic strip foundations, shed bases, garage bases or light external slabs. The exact suitability depends on thickness, load, ground conditions and exposure.

GEN concrete is useful because it is simple to order, widely available and familiar to ready-mix suppliers. However, it should not automatically be used for reinforced concrete or aggressive exposure. If reinforcement is present, if chloride exposure is possible, or if a structural engineer is providing working, a designatedRCmix or a designed concrete specification is usually more appropriate.

RC Concrete Types

RC concreteis designated for reinforced concrete. It is used where concrete and steel reinforcement work together to resist bending, shear, compression and tensile forces. Reinforced concrete requires more than a strength number: it needs correct cover to reinforcement, exposure class, crack control, compaction, curing and design detailing. A simple C25/30 strength is not enough information for a durable external reinforced slab if exposure classes are ignored.

For domestic projects, RC mixes may appear in structural raft slabs, reinforced ground beams, retaining walls, suspended slabs and engineered foundations. For commercial projects, RC concrete is central to frames, columns, slabs, pile caps, retaining structures and infrastructure works. Always follow the engineer’s specification rather than substituting a cheaper general mix.

PAV Concrete Types

PAV concreteis intended for paving, external slabs and vehicle areas. The key issue is not only vehicle loading but also freeze-thaw durability. External concrete can become saturated with water and then freeze. If de-icing salts are used, deterioration can accelerate. PAV mixes are commonly selected for driveways, parking bays, external hardstanding and industrial yards, but the correct choice depends on salt exposure, traffic level and finish.

FND Concrete Types

FND concreteis used for foundations where the ground contains sulfates or other conditions that affect durability. The correct FND class should be selected from ground investigation information, not guessed from the appearance of the soil. Clay soils, made ground, brownfield sites and some fill materials can require a higher durability specification than a standard domestic foundation mix.

Standardised Prescribed Concrete: ST Mixes Explained

Standardised prescribed concreteis often known by ST mix names such as ST1, ST2, ST3, ST4 and ST5. These mixes are not chosen in the same way as designed concrete. Instead of specifying full performance requirements, the mix proportions are prescribed within the standard. They are mainly suitable for straightforward applications where design responsibility and durability risk are limited.

ST mixes are still encountered in domestic building, small civil works and some site-mixed concrete references. However, many ready-mix suppliers and specifiers prefer designated or designed concrete because they provide clearer performance and durability alignment. In 2026, the safest approach is to use ST mixes only where the application is simple and non-critical, and to use BS 8500 designated or designed concrete for anything structural, reinforced, exposed or inspected by Building Control.

• ST Mix: ST1; Typical Use: Weak blinding, cavity fill, kerb backing, mass fill; Risk Level: Low; Modern Ordering Advice: Use only for non-structural applications
• ST Mix: ST2; Typical Use: General bedding, simple paths, low-duty domestic work; Risk Level: Low; Modern Ordering Advice: Often replaced by GEN1 or GEN2
• ST Mix: ST3; Typical Use: Light domestic slabs and footings where appropriate; Risk Level: Medium; Modern Ordering Advice: Check if GEN3 or RC mix is more suitable
• ST Mix: ST4; Typical Use: House floors, garage floors and lightly loaded slabs; Risk Level: Medium; Modern Ordering Advice: Use designated/design mix for exposure-critical work
• ST Mix: ST5; Typical Use: Higher-strength prescribed applications; Risk Level: Higher; Modern Ordering Advice: Designed concrete may be preferable

Do Not Treat ST Mixes as Universal Strength Classes

ST names are not the same as a complete designed concrete specification. For engineered work, order the exact mix specified by the designer or ready-mix technical department rather than converting loosely between ST, GEN and C-class labels.

Concrete Strength Classes: C8/10 to C50/60

Concrete strength classes describe compressive strength, normally tested at 28 days. A class such asC25/30includes two values: cylinder strength and cube strength. The first number is the cylinder strength in MPa, and the second number is the cube strength in MPa. UK site discussions often use the cube value because cube tests have long been common in British practice.

Strength class is important, but it does not fully define concrete. Two C30/37 mixes can behave differently if they have different water/cement ratios, cement combinations, aggregate grading, air entrainment, admixtures, consistence or exposure requirements. For durability-critical work, the exposure class and limiting values matter alongside the C-class.

• Strength Class: C8/10; Typical UK Use: Blinding and weak fill; Suitable For: Levelling layer below structural concrete; Specification Note: Non-structural
• Strength Class: C12/15; Typical UK Use: Light fill, bedding, kerb backing; Suitable For: Low-load support and general fill; Specification Note: Routine
• Strength Class: C16/20; Typical UK Use: Domestic footings, shed bases, simple slabs; Suitable For: Light domestic applications; Specification Note: Check exposure
• Strength Class: C20/25; Typical UK Use: Garage floors, house floors, domestic slabs; Suitable For: General building work; Specification Note: Common domestic grade
• Strength Class: C25/30; Typical UK Use: Driveways, reinforced slabs, foundations; Suitable For: Moderate structural and external work; Specification Note: Use correct exposure class
• Strength Class: C30/37; Typical UK Use: Structural RC, heavy driveways, retaining walls; Suitable For: Higher duty domestic/commercial work; Specification Note: Designer measurement advised
• Strength Class: C35/45+; Typical UK Use: Commercial slabs, frames, civil engineering; Suitable For: Engineered structures; Specification Note: Engineer specified

Specialist Types of Concrete Used in the UK

Beyond common GEN, RC, PAV and FND concretes, the UK market includes many specialist concretes designed for speed, placement, appearance, durability, sustainability or unusual exposure. These products are often supplier-specific, so the name may differ between ready-mix companies. Always confirm the performance data sheet, certification, curing requirements and compatibility with the structural design.

Waterproof Concrete

Used for basements, tanks, retaining walls and below-ground structures. It normally requires a full waterproofing design strategy, not just a waterproof admixture.

Fibre Reinforced Concrete

Contains steel, polypropylene or macro-synthetic fibres to help crack control, impact resistance or slab performance. It must be designed for the intended duty.

Self-Compacting Concrete

Flows around reinforcement and complex formwork with minimal vibration. Useful for congested reinforcement, architectural work and difficult pours.

Rapid-Strength Concrete

Formulated for early strength gain where fast opening, repair work or short possession time matters. Curing and temperature control remain critical.

Lower-Carbon Concrete

Uses cement combinations and supplementary cementitious materials to reduce embodied carbon while meeting BS 8500 performance requirements.

Decorative Concrete

Includes coloured, stamped, polished and exposed aggregate concrete. Appearance depends heavily on finishing, curing, sample panels and weather control.

Waterproof Concrete

Waterproof concrete is commonly used in basements, retaining walls, lift pits, swimming pools, tanks and below-ground plant rooms. The phrase can be misleading because watertight performance depends on design, joint detailing, crack width, waterbar installation, workmanship and curing. A waterproof admixture can help, but it cannot compensate for uncontrolled cracking, poor joints or incorrect cover.

Fibre Reinforced Concrete

Fibre reinforced concrete includes micro-synthetic fibres for plastic shrinkage control, macro-synthetic fibres for slab performance, and steel fibres for higher structural or impact requirements. Fibres can reduce the need for traditional mesh in some slabs, but substitution should only be made where the slab design and supplier technical data support it.

Foamed and Lightweight Concrete

Foamed concrete and lightweight concrete are used for void filling, trench reinstatement, roof falls, insulation layers, ground stabilisation and weight-sensitive construction. They are not chosen by ordinary C-class strength alone. Density, flow, thermal performance, drying shrinkage and compatibility with subsequent layers are central to the specification.

Architectural and Decorative Concrete

Decorative concrete may include pigment, exposed aggregate, polished surfaces, stamped patterns, acid-etched finishes or specialist formwork. The key risk is expectation mismatch. Always agree sample panels, colour tolerance, joint layout, curing method and sealing system before the pour. Decorative concrete is a finishing system as much as a structural material.

Exposure Classes: The Hidden Factor Behind Concrete Type Selection

Exposure class describes the environment the concrete must survive. It is one of the most important parts of concrete specification because many concrete failures are durability failures rather than simple strength failures. A slab can reach its 28-day strength yet still scale, crack or corrode reinforcement if it was not specified for frost, chlorides, sulfates or chemical attack.

• Exposure Class Family: XC; What It Means: Carbonation-induced corrosion risk; Common UK Examples: Reinforced internal and external concrete; Concrete Selection Impact: Controls cover and w/c ratio
• Exposure Class Family: XD; What It Means: Chlorides not from seawater; Common UK Examples: Car parks, roads, de-icing salts; Concrete Selection Impact: Requires chloride durability design
• Exposure Class Family: XS; What It Means: Seawater chlorides; Common UK Examples: Marine and coastal structures; Concrete Selection Impact: Specialist durability design
• Exposure Class Family: XF; What It Means: Freeze-thaw attack; Common UK Examples: Driveways, external slabs, saturated flatwork; Concrete Selection Impact: May need air entrainment and PAV mix
• Exposure Class Family: XA; What It Means: Chemical attack; Common UK Examples: Sulfate ground, aggressive soils, industrial exposure; Concrete Selection Impact: May require FND or designed mix

Exposure Can Override Strength

A higher strength number does not automatically make concrete durable. For example, external concrete exposed to freeze-thaw and de-icing salts may require air entrainment and an appropriate paving designation, not simply a stronger non-air-entrained slab mix.

Foundations and Ground Conditions

Foundation concrete should be selected after considering soil type, groundwater, sulfates and site contamination. For simple domestic foundations in non-aggressive ground, a common designated foundation mix may be suitable. Where aggressive ground is identified, FND concrete or a designed concrete specification should be used. Brownfield sites, made ground and unusual fill require more caution than clean natural ground.

Driveways and External Flatwork

Driveways are frequently under-specified because they appear simple. In reality they combine vehicle loading, surface water, freeze-thaw exposure, occasional de-icing salts, abrasion and finishing risk. For a long-lasting driveway, concrete type, thickness, reinforcement, sub-base, joints, curing and surface finish must all work together. Ordering a generic “C25 mix” without exposure and finishing guidance can lead to surface scaling or cracking.

Reinforced Concrete

Reinforced concrete is sensitive to cover, compaction and durability because the steel must be protected from corrosion. The concrete type must be compatible with the exposure class and the reinforcement detailing. If the structural drawings specify a designed concrete class, do not downgrade it to a cheaper general-purpose mix. The concrete is part of the structural safety system.

How to Order the Right Concrete Type in the UK

Ordering concrete correctly is not just about asking for “a strong mix”. A ready-mix supplier needs enough information to supply concrete that can be placed, finished and cured successfully while meeting the required performance. In 2026, the best orders include project use, concrete designation or designed class, exposure, consistence, maximum aggregate size, delivery method and quantity.

• Confirm the specification route:designated concrete, designed concrete, prescribed concrete or proprietary specialist product.
• State the element:foundation, slab, driveway, floor, retaining wall, beam, column, path or yard.
• State reinforcement:plain, mesh, rebar cage, fibres or heavily reinforced.
• Confirm exposure:internal, external, freeze-thaw, de-icing salts, sulfate ground, marine or chemical exposure.
• Choose consistence:S2, S3, S4 or flow class depending on placement, pumping and finishing needs.
• Confirm aggregate size:10mm may be needed for congested reinforcement; 20mm is common for general work.
• Work out quantity:order measured volume plus sensible waste allowance, normally 5–10% for simple pours and more for irregular excavations.
• Plan access:direct chute, barrow, dumper, pump or line pump. Placement method affects workability and timing.

Good Ordering Phrase

“I need 5.5m³ of PAV2 concrete for a domestic driveway, external freeze-thaw exposure, 100mm thick slab on compacted sub-base, mesh reinforcement, S3 consistence, 20mm aggregate, delivered by chute if access allows.”

Common Concrete Ordering Mistakes

The most common mistake is ordering by habit: “same as last time”, “C25 will do”, or “foundation mix please”. This can work for routine jobs but fails where the exposure or structural risk is different. Another common mistake is changing water content on site to make concrete easier to place. Adding water beyond the designed amount can reduce strength, increase shrinkage, weaken the surface and invalidate the supplied mix performance.

For small projects, also avoid under-ordering. A short load can be extremely expensive because a second lorry, delivery fee and delay may cost more than the small extra quantity you tried to save. For foundations and irregular ground, measure carefully and allow for overbreak. For slabs, check thickness at multiple points rather than assuming the sub-base is perfectly level.

Lower-Carbon Concrete Types in 2026

Lower-carbon concrete is no longer a niche topic. UK concrete suppliers now offer mixes using cement combinations, additions and supplementary cementitious materials to reduce embodied carbon while maintaining performance. The 2023 update to BS 8500 widened the ability to specify lower-carbon concretes, and by 2026 many public, commercial and domestic projects are asking for carbon information alongside price and strength.

Lower-carbon does not mean weaker or experimental when correctly specified. It means the cementitious system is chosen to reduce carbon while still meeting the required strength, durability, setting time and finish. However, lower-carbon binders can affect early strength gain, colour, finishing window and cold-weather performance. Contractors should discuss curing time, striking time and programme requirements before switching from a traditional mix.

GGBS / Slag Cement Blends

Can reduce embodied carbon and improve some durability properties, but may slow early strength gain, especially in cold weather.

Fly Ash / Pozzolanic Additions

Used where available to reduce clinker content and influence workability, heat of hydration and long-term strength development.

EPD-Based Ordering

Environmental Product Declarations help compare concrete carbon data, but mixes must still meet performance and durability requirements.

Concrete Type by UK Project

The table below is a practical starting point for selecting concrete types. It is not a substitute for drawings, structural design checks, ground investigation or supplier technical advice. It helps homeowners, builders and site managers understand the likely concrete family before confirming the final specification.

• Project: Blinding Layer; Likely Concrete Type: GEN0 / GEN1 / ST1; Typical Strength Range: C8/10 – C12/15; Important Checks: Non-structural levelling only
• Project: Domestic Strip Footing; Likely Concrete Type: GEN1–GEN3 or FND where required; Typical Strength Range: C12/15 – C20/25; Important Checks: Soil, sulfate, Building Control
• Project: Shed Base; Likely Concrete Type: GEN2 / GEN3; Typical Strength Range: C16/20 – C20/25; Important Checks: Sub-base and slab thickness
• Project: Garage Base; Likely Concrete Type: GEN3 / C20/25 / RC25; Typical Strength Range: C20/25 – C25/30; Important Checks: Vehicles, DPM, mesh, joints
• Project: Driveway; Likely Concrete Type: PAV1 / PAV2; Typical Strength Range: C25/30 – C30/37; Important Checks: Freeze-thaw, de-icing salts, finish
• Project: Retaining Wall; Likely Concrete Type: RC designed concrete; Typical Strength Range: C25/30+; Important Checks: Engineer design, drainage, cover
• Project: Industrial Floor; Likely Concrete Type: Designed concrete / fibre mix; Typical Strength Range: C30/37+; Important Checks: Abrasion, flatness, loading, joints
• Project: Agricultural Yard; Likely Concrete Type: PAV / designed chemical-resistant mix; Typical Strength Range: C30/37+; Important Checks: Manure, silage, abrasion, drainage

Concrete Type Selection Affects Safety, Durability and Cost

This guide explains common UK concrete types for planning and budgeting. For structural, reinforced, external, chemically exposed or Building Control projects, use the engineer’s specification or ask a qualified ready-mix technical team to confirm the correct BS 8500 concrete designation.

Types of Concrete UK — Frequently Asked Questions

Common questions about GEN, RC, PAV, FND, C-class concrete, ready-mix ordering and BS 8500 specifications in 2026.

For simple domestic strip foundations in non-aggressive ground, a GEN or suitable foundation-designated concrete is commonly used. However, the correct concrete depends on ground conditions, sulfate risk, foundation design, Building Control requirements and whether the foundation is reinforced. In made ground, clay with sulfate risk or brownfield conditions, an FND class or designed concrete may be required.

GEN concrete is a general-purpose designated concrete family used for routine domestic and non-structural or lightly structural applications. RC concrete is intended for reinforced concrete elements where steel reinforcement, cover, durability and structural performance are part of the specification. If reinforcement is present, especially in a structural element, RC or designed concrete should normally be used rather than a generic GEN mix.

No. C25/30 is a strength class, while GEN3 is a designated concrete type. They may overlap in some practical uses, but they are not the same specification. A complete concrete order should consider strength, exposure, consistence, aggregate size, reinforcement, delivery method and durability. Avoid replacing one label with another unless a supplier or designer confirms equivalence for the exact application.

Driveways usually need a paving concrete such as PAV1 or PAV2, depending on vehicle loading, freeze-thaw exposure and de-icing salt risk. For domestic cars on a well-prepared sub-base, PAV1 may be suitable in many cases. Where heavier vehicles, winter salts or more severe exposure are expected, PAV2 or a designed external slab mix may be needed. Thickness, reinforcement, joints and curing are just as important as the mix name.

FND concrete is used for foundations where the ground environment, especially sulfate content, requires a durability-specific foundation concrete. The correct FND class should come from ground investigation or site-specific advice. It is commonly relevant for clay soils, made ground, fill, brownfield sites and sites where aggressive chemical conditions may affect buried concrete.

Reinforced concrete should normally use an RC designated concrete or a designed concrete specification that states strength class, exposure class, chloride class, consistence, maximum aggregate size and any special requirements. The best type depends on the structural design and exposure. For retaining walls, beams, suspended slabs and heavily loaded elements, follow the engineer’s drawings and do not substitute a general-purpose mix.

Bagged concrete is useful for small repairs, posts, minor pads and very small slabs. Ready-mix concrete is usually better for foundations, driveways, garage slabs and larger pours because batching is controlled, delivery is faster and consistency is higher. For structural or Building Control work, check whether bagged concrete is acceptable and whether it can meet the required strength and durability specification.

S3 refers to consistence or slump/workability, not strength. It indicates how workable the concrete is when placed. S3 is common for many general pours, while S4 may be used where easier placement or pumping is required. Higher workability should be achieved by the correct mix or admixture, not by adding extra water on site.

Yes, lower-carbon concrete can be suitable for domestic work where it meets the required BS 8500 performance, strength and durability criteria. It may be used for foundations, slabs and other elements, but setting time and early strength gain can differ from traditional mixes. Discuss programme, weather, finishing and curing with the supplier before ordering.

Responsibility depends on the project. For simple domestic work, the builder and supplier may help select a suitable designated mix. For engineered, reinforced, structural, commercial or durability-critical work, the structural engineer or designer should specify the concrete. The supplier then produces concrete to that specification. The person ordering must ensure the order matches the approved drawings and design requirements.

Related UK Concrete Guides & Guides

Use these related resources to work out quantities, compare specifications and plan your next concrete order.