Leading manufacturer and supplier of ready mix concrete, liquid screed and concrete pumps for the South West

Types of Concrete Mix and Their Uses

 

Concrete comes in many different forms, but can broadly be sorted into four categories: standard concrete, designated concrete, designed concrete, and proprietary concrete. There are a number of different grades within these categories.

The ‘best’ concrete to buy depends on the application you plan to use it for. Choosing the correct type is important because it ensures that your new build will be hard-wearing and stand the test of time.

Wright Readymix are one of the UK’s leading concrete specialists. We supply high-quality concrete solutions to the South West of England and South Wales, including ready-mixed concrete, liquid screed, and concrete pumps. In this guide, we cover everything you need to know about the different types of concrete, including their various strengths and applications.

Standardised Concrete

 

Standardised Prescribed Concretes (SPCs) are made with a prescribed quantity of materials issued by the British Standards body.

Relatively simple mixes, they are typically used for small scale jobs and mixed on site or obtained from a supplier. They have no strength guarantee or defined quality standards. There are five types:

Also known as wet lean mix concrete, this versatile mix is commonly used for a wide variety of non-structural applications.

Strength: Estimated at 7.5N/mm2 after 28 days

Uses:

  • Drainage works
  • Backing
  • Haunching
  • Kerb bedding
  • Blinding
  • Cavity filling

A multipurpose mix used for unreinforced building and housing applications. When combined with a liquid screed finish, it is an excellent choice for house foundations and bases.

Strength: Estimated at 10N/mm2 after 28 days

Uses:

  • Foundations for houses and extensions
  • Non-structural mass concrete
  • Unreinforced strip footings
  • Footings for fence posts
  • Small bases for patios
  • Drainage works
  • Blinding

Although ST3 is unsuitable as a wearing surface, it is frequently used for light domestic applications and bases. It can be used for internal floor slabs and house floors with no permanent finish flooring.

Strength: Estimated at 15N/mm2 after 28 days

Uses:

  • Foundations for sheds, garages, greenhouses, and walls
  • Paving for patios
  • Trench filling
  • Blinding house floors

ST4 can be used as a wearing surface for light foot traffic. It is used for a range of domestic, industrial, and agricultural applications.

Strength: Estimated at 20N/mm2 after 28 days

Uses:

  • Drain bedding
  • Benching to chambers
  • Unreinforced garage floors
  • Workshop and shed bases
  • Internal floor slabs

ST5 can be used in domestic, commercial, and agricultural projects, but only for light foot traffic applications.

Strength: Estimated at 25N/mm2 after 28 days

Uses:

  • Foundations for columns and posts
  • Equipment storage spaces
  • Building ground floor slabs

Designated Concrete

 

Designated concretes are identified by their application, whether agricultural, industrial, or structural. They provide peace of mind that the chosen concrete will perform as needed, letting you skip the long process of specifying a designed concrete.

Providers of designated concrete must hold the appropriate level of product conformity certification, as approved by the BSI Standards Policy and Strategy Committee.

Designated concretes are sorted into General (GEN), Reinforced (RC), Foundation (FND), and Pavement (PAV) categories, each designed for a variety of applications.

General

 

GEN concrete is used for domestic and non-structural applications. It has a relatively low strength and durability level. The requirements specify a minimum quantity of cement to be included, but no water cement ratio.

Unless fully encased or covered,GEN concretes should only ever be used for internal applications.

GEN0 is a wet lean mix concrete often used in both commercial and housing projects.

Strength: Estimated at 7.5N/mm2 after 28 days

Uses:

  • Domestic foundations
  • Cavity filling
  • Mass filling
  • Kerb bedding
  • Benching
  • Haunching

GEN1 is multifunctional concrete used for general building and housing applications.

Strength: Estimated at 10N/mm2 after 28 days

Uses:

  • Foundations for conservatories, sheds, walls, and steps
  • Trench filling
  • Cavity filling
  • Mass filling
  • Blinding house floors
  • Kerbing
  • Drainage works
  • Haunching

GEN2 is perfect for domestic floors where no permanent finish will be installed, but carpeting or tiling will be.

Strength: Estimated at 15N/mm2 after 28 days

Uses:

  • Trench fill foundations
  • Foundations for conservatories, sheds, and walls
  • Unreinforced strip footings
  • Unreinforced mass concrete fill
  • Paving for paths
  • Blinding

GEN3 can be used for light duty domestic foundations and applications. It can be used for domestic garage floors and to build unembedded internal floor slabs that will be covered by tiles, carpet, or laminate flooring.

Strength: Estimated at 20N/mm2 after 28 days

Uses:

  • Foundations for houses, garages, and walls
  • Bases for driveways and sheds
  • Unreinforced bases and oversites for conservatories and greenhouses
  • Domestic garage floors (with no embedded metal)
  • Under paving for patios
  • Mass concrete fill
  • Trench fill foundations
  • Blinding

Designated Reinforced Concretes

 

Reinforced concretes are composites pre-stressed or embedded with steel. They are strengthened with added components to prevent cracking or corrosion.

Reinforced concretes have specified requirements for minimum cementitious content .and maximum water-concrete ratios. They are ideal for builds that will be exposed to highly demanding conditions.

RC25 concrete mixes can be used in parts of a building that require steel reinforcement.

Strength: Estimated at 25N/mm2 after 28 days

Uses:

  • Lightly reinforced house or garage floors
  • Foundations, footings, and basement floors
  • Bases for sheds or outbuildings
  • Infill to insulated concrete formwork located above ground

This mix is suitable for mild exposure conditions, like pavements and driveways.

Strength: Estimated at 30N/mm2 after 28 days

Uses:

  • Driveways, walkways, paths, stables, and patios
  • Internal areas for light foot and trolley traffic
  • Slabbing
  • Some reinforced foundations

RC28/35 is a strengthened concrete ideal for moderate exposure conditions.

Strength: Estimated at 35N/mm2 after 28 days

Uses:

  • External slabbing, column bases, walls, and beams
  • Garages and workshops
  • Livestock and crop storage floors
  • Piling
  • Tank fill

RC32/40 is suitable for moderate to high exposure conditions.

Strength: Estimated at 40N/mm2 after 28 days

Uses:

  • Agricultural tracks and roads
  • Floors and walls for slurry and manure storage
  • Cavity infill to reinforced masonry
  • Farmyards
  • Factory floors

RC35/45 is appropriate for high demanding exposure conditions.

Strength: Estimated at 45N/mm2 after 28 days

Uses:

  • Toppings for floors in parlours and dairies
  • Floors and walls for silage or grain stores
  • Stable floors

RC40/50 is the hardiest of reinforced concretes, making it suitable for severe exposure conditions.

Strength: Estimated 50N/mm2 after 28 days

Uses:

  • External yards
  • Heavy traffic areas
  • Stable floors
  • Toppings for floors in parlours and dairies
  • Floors and walls for silage or grain stores

Designated Paving Concrete

 

PAV1 and PAV2 concretes include freeze-thaw resistance and are intended for heavy-duty parking and drives. They are not suitable for power float finishes.

PAV1 mixes are frequently used for domestic pavement construction. They contain an additive that creates micro-sized air bubbles in the concrete, helping protect the surface from freeze-thaw cycles.

Strength: Estimated at 35N/mm2 on 28 days

Uses:

  • Domestic pavements, parking, and carports (where no de-icing salts are used)
  • Reinforced and unreinforced bases for workshops and houses
  • Reinforced and unreinforced hard standings
  • Paved areas such as walkways and patios
  • External paving
  • House driveways

PAV2 is a heavy-duty concrete suitable for commercial and industrial use. It is resistant to frost and can be used with de-icing salts.

Strength: Estimated at 40N/mm2 after 28 days

Uses:

  • Reinforced bases for commercial buildings and agricultural storage
  • Slabbing and paving with heavy vehicle and machinery traffic
  • External yards and roads subject to occasional de-icing salts
  • Heavy-duty outdoor driveways, pavements, and forecourts
  • Industrial external car parks
  • Mass concrete fills

Designated Foundation Concretes

 

As the name suggests, foundation concrete is used in foundations, specifically in those where the ground soil contains sulphates. Sulphates can cause normal concrete to soften, decay, or crack; foundation concrete is designed to withstand this deterioration.

FND2, FND3, and FND4 can be used in all types of un-reinforced foundations. Each is designed for a different soil type.

Strength: Estimated at 30N/mm2 after 28 days

Designed Concretes

 

As directed by European Standards, designed concretes are mixed to achieve a specific strength required for an application. Unlike standardised and designated concretes, they don’t specify the cement to water mix ratios.

Proprietary Concretes

 

Proprietary concretes are custom mixed by the producer for a specific application. They are used where high-performance or specific qualities are required. The producer will provide you with a performance guarantee.

 

Get a Quote From our Concrete Specialists 

 

Wright Readymix have been supplying premium concrete mixes to the South and Wales for over two decades. We can supply your project with ready-mix concrete of all types, as well as heavy-duty concrete pumps and equipment. No matter the size or scope of your project, you can rely on us for quality materials and a top-notch service.

Get a quote online or by calling us on 0117 958 2090. We’re happy to talk through your requirements and offer our recommendations on the best concrete type for your project.

Concrete Mixes FAQs

 

We suggest concrete mixes depending on application requirements and ground conditions. Contact a member of our expert team to discuss the details of your project and we will be able to suggest the best concrete mix to suit your needs.

This will depend totally on the size of your lay site. Use our useful concrete volume calculator to find out how much concrete mix you’ll require for your project.

If you do not have a credit account with us, then our preferred method of payment is by credit or debit card.

Cure time will depend on a number of factors, such as the type of concrete mix being used and external weather conditions, however, you should have at least between 1-2 hours in which to lay the mix. We will be able to advise you more accurately once we have more details, so don’t hesitate to contact us. 

All of our concrete delivery vehicles come with chutes that can deliver ready mix concrete up to approximately 2.4m away from the rear of the vehicle and 1.2m from the side. If your lay site has restricted access that would make delivery by normal means impossible, then one of our concrete pumps for hire would be able to transport the concrete to your lay site with ease.

The minimum width required for our vehicles is 2.7m or 8ft 10 inches. If you believe that entry to your site would be particularly tricky for one of our delivery vehicles, then we would be happy to arrange for one of our team to inspect your site beforehand. You can also request delivery through our mini pump, which is perfect for accessing lay sites that are too hard to navigate for larger vehicles.

If you wish to move the concrete mix yourself i.e. with a wheelbarrow or dump truck, then you should request your ready mix concrete at a lower slump. This will mean that it is drier and therefore easier to transport manually. Please let us know in advance if you wish for our concrete mixers to offload directly into your wheelbarrow, so that we can schedule appropriately.

Our delivery trucks remain on site for an allotted time of 30 minutes. If you require the delivery truck for longer than this time, then this may incur you a waiting time charge.

Yes – without tamping, vibrating, or compacting, air pockets would remain trapped inside the wet concrete mix. These air pockets could seriously weaken the overall structure of the concrete, making it weaker and less durable than it would be if the concrete was made denser. When reinforcing metal is used, this method also ensures that the concrete best bonds to the metal.

Concrete mixes can be harmful if not handled correctly. That is why we always suggest wearing the appropriate safety gear and following these guidelines when handling our ready mix concrete or liquid screed:

  • Fresh concrete or screed can cause burns to the skin and eyes, so wear protective clothing (impervious boots, goggles, gloves, long sleeves and trousers)
  • If concrete makes contact with your skin or eye, then wash it off thoroughly or rinse from your eye immediately.
  • Do not swallow. If any concrete mix is ingested, seek immediate medical advice.
  • Once finished, remove your clothing and wash it thoroughly before reuse.

     

We have a large fleet of delivery vehicles in a range of sizes and capacities (length + width + height = capacity):
6.5m + 2.5m + 4m = 4m3
7.5m + 2.5m + 4m = 6m3
8.7m + 2.5m + 4m = 7.5m3

We are the right people for you – let’s work together!
Contact us on 0117 958 2090 today to get a quote or to find out more.

News
Is It Cheaper to Pour Concrete or Use Concrete Blocks?
22nd April 2026

When the budget is tight, the question of cheaper concrete comes up early. Should you pour ready mix concrete or lay a concrete block wall? Both methods use concrete, but the costs behind them are quite different. Concrete costs catch many builders out. You price up materials, forget about equipment hire, underestimate the labour, and suddenly a job that looked affordable is running over budget.

Material prices, labour rates, equipment hire, even long-term maintenance... these all affect the calculation for your project. A driveway and a garden wall do not follow the same cost logic, and choosing the wrong method can add hundreds to a job that should have been straightforward. Use our concrete volume calculator below to determine the exact amount of concrete required for your project.

This article covers the full cost breakdown, with realistic UK figures to guide your decision before work starts on site.

What Do Concrete Materials Actually Cost?

Ready-mix concrete is priced per cubic metre. According to Checkatrade, the average cost of ready-mix concrete in the UK is around £120 per m³, with prices ranging from £100 to £160 per m³ depending on your region, grade, and supplier. Delivery adds a further £100-£200 on top of that. For a typical domestic foundation measuring 6m x 0.6m x 0.3m, you would need roughly 1.1m³, putting material and delivery costs combined at around £210 to £375 before any equipment or labour is factored in [1].

Concrete blocks are priced per unit. A standard 440 x 215 x 100mm dense aggregate block costs between £1.50 and £2.50 at builders' merchant prices. For the same foundation run, you would need considerably more blocks than that figure suggests once you account for mortar, waste, and coursing. At a small project scale, the per-unit cost of blockwork can appear lower, but the volume required often closes that gap quickly.

At medium scale, poured concrete becomes more cost-efficient. Ready-mix is ordered in bulk and priced accordingly, so larger pours benefit from a lower effective cost per m³. Blockwork does not scale in the same way, and material costs rise proportionally with each additional course.

For a more detailed look at how ready-mix concrete is priced in the UK, including grade variations and supplier considerations, our ready mix concrete prices guide covers the full breakdown.

The Real Cost Difference Sits in Labour & Equipment

Pouring concrete requires less skilled labour than laying blocks, but carries higher equipment costs. Hiring a mixer, vibrating poker, and shuttering can add £150-£300 or more to a domestic job, with pump hire pushing costs higher still. The work is also faster, which keeps day-rate labour costs lower overall.

Blockwork is more labour-intensive and requires a skilled tradesperson, typically charging £150-£250 per day. A job that takes one operative a day in poured concrete could take two days of skilled blockwork. According to the Building Cost Information Service (BCIS), construction labour costs are forecast to rise 15% between Q1 2026 and Q1 2031, with 62% of professionals surveyed expecting an uplift in the next 12 months. A shrinking skilled workforce is a key driver, and blocklaying sits squarely in the trades most affected [2].

For DIY projects, blockwork is more forgiving than managing a ready-mix pour, which has a narrow working window and less room for error. However, if you are weighing up whether to manage the pour yourself or bring in a professional, our guide to the dangers of DIY concrete pouring is worth reading before you commit.

Maintenance & Durability Catches Builders Out Long Term

Poured concrete, when correctly specified, has a long service life with minimal maintenance. According to the Concrete Centre's (CC) guide to BS 8500, concrete is designed for intended working lives of 50 or 100 years, with many project specifications adopting 60 years as standard. Achieving that lifespan depends on selecting the right exposure class, strength grade, and cement type for the conditions the structure will face. Get those decisions wrong, and maintenance costs will follow [3].

Concrete blocks perform well in above-ground applications such as walls and retaining structures. Individual units can be replaced without disturbing the surrounding structure, making localised repair more straightforward than remedying a cracked slab. However, mortar joints are a potential weak point over time, particularly in exposed or wet conditions where freeze-thaw cycling can accelerate deterioration.

For both methods, the long-term cost case is the same: correct specification at the outset is cheaper than remedial work later. For a practical look at the most common causes of concrete deterioration and how to address them, our guide, troubleshooting concrete cracking: common causes & fixes, covers the key failure points.

Proven Tips to Keep Your Build Costs Down

There are practical steps you can take to keep costs down, whichever method you choose.

Use these three principles to control costs on site:

  • Plan your pour volume carefully to avoid ordering more concrete than the job requires.
  • Combine methods where it makes sense, such as pouring a concrete base and using blocks for the wall above it.
  • Choose the correct mix grade or block type for the application rather than over-specifying.

Ordering ready-mix concrete in a single pour is more cost-efficient than splitting delivery across multiple smaller loads. Each delivery carries a minimum charge, so consolidating your order saves money. For blockwork, buying in full packs from a builders' merchant reduces waste and unit cost compared to buying loose.

So, Which Method is Cheaper?

Before the figures are available, it is easy to assume that one method is simply cheaper than the other. Once you account for materials, labour, equipment, and the structure's lifetime, the answer depends on what you are building and at what scale. For larger pours, foundations, and slabs, ready-mix concrete is usually the more cost-efficient choice once labour time and equipment are factored in. For smaller above-ground structures or projects where a skilled labourer is already on site, blockwork can be cost-competitive.

Wright Readymix supplies ready-mix concrete and concrete blocks to domestic and commercial projects across Bristol, Avonmouth, Newport, Cheddar, and Paignton. With five concrete plants across the South West and South Wales, a 24/7 team, and the backing of The LGW Group, we are well placed to advise on mix specification, volume, and the most cost-effective approach for your project.

Call 0117 958 2090 or get in touch to discuss which option suits your project and budget.

External Sources

[1] Checkatrade, What Is the Cost of Ready Mix Concrete per M³: https://www.checkatrade.com/blog/cost-guides/ready-mix-concrete-cost/

[2] Building Cost Information Service (BCIS), Beyond Materials: Why Labour Costs Remain a Key Pressure Point for Construction: https://www.bcis.co.uk/insight/beyond-materials-why-labour-costs-remain-a-key-pressure-point-for-construction/

[3] Concrete Centre (CC), How To Design Concrete Structures Using Eurocode 2, BS 8500 for Building and Civil Structures: https://www.concretecentre.com/getmedia/89d9767b-4a4b-468c-8f78-cd05c8294b21/MB_FD_HowToGuide_Feb24.aspx

Read more
Is Cast-In-Place Concrete Better Than Precast Concrete Blocks?
13th April 2026

Concrete or concrete blocks? It's one of the most common specification debates in UK construction, and one of the most consequential. Get it wrong, and you're dealing with mortar joint failure, differential settlement, or foundations that aren't suited to your ground conditions. These are costly problems that are far harder to fix once the build is underway.

Both materials have a legitimate place on-site. The real question is which is right for your specific application, ground type, and programme. Cast-in-place concrete and precast concrete blocks perform very differently below ground versus above it. Understanding that distinction is what separates a sound specification from an expensive one.

This guide covers strength, build time, cost, and foundation suitability, so you can make the right call before work starts.

What is Cast-in-Place Concrete?

Cast-in-place concrete, also known as poured or in-situ concrete, is batched at a plant, delivered by mixer truck, and poured directly into formwork on site. Once set, it forms a single, continuous structure with no joints or bonding interfaces. This gives it a significant structural advantage for foundations, retaining walls, and ground slabs.

Ready-mix concrete can be specified across a wide range of applications, from trench-fill foundation work to high-strength structural pours. The British Ready Mixed Concrete Association (BRMCA) requires members to hold product conformity certification under either the Quality Scheme for Ready-Mixed Concrete (QSRMC) or the British Standards Kitemark Scheme, both approved to BS EN ISO 9001, ensuring every pour is produced and tested to an independently verified standard [1].

What Are Concrete Blocks?

Concrete blocks are precast units manufactured off-site and delivered ready to lay. They're a familiar material for groundworkers and bricklayers, and are widely used in:

  • Cavity wall construction
  • Below-ground masonry and retaining walls
  • Internal partition walls
  • Above-ground load-bearing walls

Blocks vary considerably in density and compressive strength. Dense aggregate blocks are suited to structural and load-bearing applications, while lightweight thermal blocks are typically used above ground where insulation values matter.

Concrete blocks are also manufactured using recycled aggregates in many cases. This makes them one of the more environmentally considered masonry options in above-ground construction. Our team supplies dense aggregate and lightweight blocks, each tested to British Standards for compressive strength, fire performance, and thermal value, so the right specification is straightforward regardless of application.

Strength, Durability, & Build Time. Which Material Actually Performs?

For most structural applications, cast-in-place concrete has a clear performance advantage. A well-specified pour produces a monolithic structure capable of resisting hydrostatic pressure and differential ground movement. These are two failure conditions that mortar-jointed construction is significantly more vulnerable to, particularly in below-ground applications.

The National House Building Council (NHBC) Standards 2024 (Chapter 4.3) specify designated mix GEN1 ST2 as the minimum concrete grade for strip and trench fill foundations. Plain unreinforced concrete must cure for at least four days before substructure masonry can proceed. However, reinforced concrete mixes require a full seven days without loading. These are Technical Requirements that NHBC-registered builders must meet, not advisory benchmarks [2].

Above ground, dense aggregate blocks offer a further advantage that is often overlooked: fire resistance. Dense concrete blocks are tested to BS EN 771-3 for aggregate concrete masonry units and are widely specified for party walls, compartment walls, and other above-ground applications where Building Regulations Approved Document B fire performance requirements apply [3].

On programme, the two methods suit different stages:

  • Both methods are sensitive to cold weather, but only ready-mix concrete can be ordered with accelerated mixes or admixtures to maintain workability and strength gain in low temperatures.
  • Blocks require no formwork. Laying can begin as soon as materials arrive, a genuine advantage for above-ground work.
  • Cast-in-place concrete requires formwork to be struck and NHBC curing periods observed before loading.
  • For irregular or non-standard designs, poured concrete is more adaptable and often faster overall.

Our article on can you pour ready mix concrete in the rain? outlines practical steps for working in marginal site conditions.

What Concrete & Blocks Actually Cost to Build With

Block and poured concrete costs depend on more than the price per unit. Concrete blocks typically have a lower material cost, but the overall project cost depends on:

  • Labour time and skill level required for laying.
  • Supervision requirements to maintain line and level.
  • Formwork materials and, where needed, pump hire for poured concrete.
  • Programme length and associated preliminaries.

For larger pours, ready-mix concrete offers meaningful economies of scale. A single delivery can cover a substantial area far more quickly than an equivalent block-laying programme. Our ready mix concrete prices guide sets out the key factors that influence material costs and how to approach budgeting.

Before committing to a specification, our concrete volume calculator can help you estimate quantities accurately and avoid over-ordering. For smaller domestic pours where a full ready-mix delivery would exceed requirements, we also offer a MiniMix service. This is a practical solution that keeps waste and costs to a minimum.

Suitability for Different Foundations & Ground Conditions

For the majority of UK foundation applications, cast-in-place concrete is the standard specification. Approved Document A (Structure) requires foundations to transmit loads safely without excessive settlement, specifying concrete at grade ST2 or GEN1 to BS 8500-2 in non-aggressive soils [4]. Strip and trench fill foundations must have a minimum thickness of 150mm and be taken to at least 450mm depth to avoid frost action, with greater depths required on shrinkable clays:

  • 750mm on low-shrinkage clay.
  • 900mm on medium-shrinkage clay.
  • 1,000mm on high-shrinkage clay.

Concrete blocks can be used in certain foundation wall applications, but ground conditions are a deciding factor. In soils with:

  • Poor drainage or high-water tables.
  • Shrinkable subsoils with a Modified Plasticity Index of 10% or greater.
  • Uneven load distribution across the footprint.

Differential movement at mortar joints makes block construction a less reliable choice below ground. Where non-engineered fill or significant ground condition variation exists, specialist design is required regardless of the material. Our concrete for foundations page covers foundation types and specifications in more detail.

Above ground, blocks are well-established for cavity walls, partition walls, and retaining structures where conditions are stable. A competent contractor will typically use poured concrete below ground and blocks above. Where there is any uncertainty around load-bearing design or ground conditions, consult a structural engineer before committing to a specification.

Which Concrete Solution Is Right for Your Project?

Choosing between cast-in-place concrete and concrete blocks doesn't have to be complicated, but it does require the right information at the right stage of the project. Specify early, specify correctly, and the material will do exactly what it's designed to do. Leave it too late or default to habit, and the cost of correcting the decision rarely stays within the original budget.

Wright Readymix supplies ready-mix concrete for domestic and commercial projects across Bristol, Avonmouth, Weston-Super-Mare, and the surrounding region. We combine local knowledge of site conditions with the supply capability of the wider LGW Group. For further guidance on mix selection, the concrete grades guide is a useful next step.

Call 0117 958 2090 or get in touch to discuss your concrete specification and project requirements directly with our team.

External Sources

[1] British Ready Mixed Concrete Association (BRMCA), Technical Excellence: https://brmca.org.uk/quality_assurance.php

[2] National House Building Council (NHBC), The NHBC Standards 2024 (Chapter 4.3): https://nhbcprod.blob.core.windows.net/shared/CC2981-NHBC-Standards-2024-aw-digital-version-lr-151223.pdf

[3] GOV.UK, Ministry of Housing, Communities and Local Government, Department for Levelling Up, Housing and Communities and Ministry of Housing, Communities & Local Government (2018 to 2021), Fire Safety: Approved Document B: https://www.gov.uk/government/publications/fire-safety-approved-document-b

[4] GOV.UK, Ministry of Housing, Communities and Local Government and Ministry of Housing, Communities & Local Government (2018 to 2021), Structure: Approved Document A: https://www.gov.uk/government/publications/structure-approved-document-a

Read more
How to Prepare the Ground for a Concrete Shed Base Step by Step
25th March 2026

A concrete shed base relies on the condition of the ground beneath it. If the area is not prepared correctly, the slab can crack, settle unevenly, or hold water, leading to repair work and reduced lifespan.

These issues are usually caused by weak ground, inconsistent excavation, or poor compaction before the concrete is placed. Preparing the base properly ensures the slab can support the load and cure evenly once poured.

Preparing the ground involves:

  • Setting out the area
  • Excavating to the correct depth
  • Installing a stable sub-base
  • Compacting the surface before pouring

This guide explains each stage clearly, so the finished base is level, stable, and ready for concrete.

Why Ground Preparation Is So Important

Ground preparation determines whether the base can carry the load of the shed and the concrete used. Planning Portal (PP) guidance states that foundations must transfer loads safely to the ground, with design influenced by soil type, nearby structures, trees, and drainage conditions [1].

For shed bases, the ground must be firm and undisturbed. Some soils, particularly clay, expand and contract with moisture changes within the top 0.75 metres, which can affect how the slab performs over time.

Preparation should focus on:

  • Reaching stable, undisturbed ground.
  • Removing soft or previously filled material.
  • Accounting for drainage and surrounding ground conditions.

For more details, this guide on troubleshooting concrete cracking: common causes & fixes explains how movement beneath the slab affects performance.

Marking Out & Excavating the Area

Marking out defines the size of the shed base, while excavation creates the depth required for the sub-base and concrete. Accuracy at this stage helps ensure the slab can be poured level.

Set out the footprint using stakes and string lines, then check diagonals to confirm the area is square. Remove topsoil, roots, and soft material, and excavate to a consistent depth, typically around 100-150mm depending on ground conditions.

Keep in mind:

  • Maintain an even excavation depth across the area.
  • Remove all unstable or organic material.
  • Keep excavated spoil away from the edges to prevent collapse.

Health and Safety Executive (HSE) guidance states that soil can exceed 1.5 tonnes per cubic metre and that excavation work should account for ground conditions, nearby services, and stability during digging [2].

Sub-Base & Compaction

The sub-base supports the concrete shed base and provides a stable surface for pouring. If it is not compacted properly, the slab can settle unevenly or develop weak areas after curing.

MOT Type 1 or crushed hardcore is typically used because it compacts into a dense, load-bearing layer. This helps distribute weight evenly and reduces the risk of movement beneath the concrete.

To achieve a reliable base:

  • Use graded aggregates that compact tightly.
  • Build up the layer in stages rather than one fill.
  • Compact each layer thoroughly to remove air gaps.
  • Check levels before pouring to maintain consistent thickness.

Our bulk bag aggregates and gravels page outlines suitable materials for shed bases and sub-bases.

Government guidance highlights that poor soil handling can lead to drainage failure and long-term defects. One case study reported remedial work costing £90,000 due to surface ponding caused by poor ground preparation [3].

Do You Need a Damp Proof Membrane?

A damp-proof membrane controls moisture from the ground and helps protect the concrete during curing and over time. Approved Document C states that floors in contact with the ground should resist moisture, prevent groundwater damage, and limit the passage of ground gases where required [4].

For shed bases, this is typically achieved by placing a membrane over a compacted hardcore layer before pouring. This helps maintain consistent curing conditions and reduces the risk of moisture affecting the slab.

Installation should follow key requirements:

  • Use polythene at least 300µm thick (1200 gauge).
  • Overlap and seal joints to maintain a continuous barrier.
  • Lay the membrane on a smooth surface to avoid punctures.

For more details, this guide on how to prepare your site for a smooth concrete delivery explains how preparation affects the finished slab.

Final Checks Before Pouring Your Concrete

Before pouring a concrete shed base, the site should be fully prepared for delivery and placement. Any issues at this stage can affect how the concrete is placed, levelled, and finished.

PP guidance highlights that site preparation should account for ground conditions, moisture, vegetation, and existing structures. It also notes that drainage should be in place to prevent moisture from affecting the slab [5].

Before pouring:

  • Confirm the base is level and ready for an even pour.
  • Check access for delivery vehicles or pumps.
  • Ensure formwork is secure and correctly positioned.
  • Remove debris, soft spots, and standing water.

If you are handling the job yourself, our ready-mix concrete for DIY builds is perfect for managing concrete on smaller projects.

Getting Your Shed Base Right from the Start

Preparing the ground correctly ensures the base is ready to support both the structure and the concrete being used. Once excavation, sub-base installation, and compaction are completed properly, the slab can be poured with greater accuracy and consistency.

Wright Readymix supplies concrete for shed bases across the South West, with reliable delivery, consistent quality, and practical advice on the right mix and volume for the job. This helps keep projects on schedule and reduces uncertainty at the point of pouring.

Call 0117 958 2090 or get in touch to arrange concrete for your shed base and get advice on the right specification for your project.

External Sources

[1] Planning Portal (PP), Outbuildings, Building Regulations: Foundations: https://www.planningportal.co.uk/permission/common-projects/outbuildings/building-regulations-foundations

[2] Health and Safety Executive (HSE), Excavations: https://www.hse.gov.uk/construction/safetytopics/excavations.htm

[3] GOV.UK, Department for Environment, Food & Rural Affairs (DEFRA), Construction Code of Practice for the Sustainable Use of Soils on Construction Sites: https://assets.publishing.service.gov.uk/media/5b2264ff40f0b634cfb50650/pb13298-code-of-practice-090910.pdf

[4] GOV.UK, Ministry of Housing, Communities and Local Government (MHCLG), Ministry of Housing, Communities & Local Government (2018 to 2021), Approved Document C: https://www.gov.uk/government/publications/site-preparation-and-resistance-to-contaminates-and-moisture-approved-document-c

[5] Planning Portal (PP), Part C – Site Preparation and Resistance to Contaminants and Moisture, Approved Document C: https://www.planningportal.co.uk/applications/building-control-applications/building-control/approved-documents/part-c-site-preparation-and-resistance-to-contaminants-and-moisture/approved-document-c

Read more
What Depth of Gravel Is Needed for Drives, Paths & Bases?
17th March 2026

Most projects require a depth of gravel between 50 mm and 200 mm, depending on how the surface will be used. Garden paths generally need shallower layers, while driveways and load-bearing areas require deeper construction over a compacted sub-base.

We supply bulk bag aggregates and gravel suitable for driveways, paths, and base preparation across domestic and commercial sites.

Selecting the right gravel depth helps prevent common problems such as rutting, shifting, or uneven ground. When the layer is too shallow, pressure from foot traffic or vehicles can push stones into the ground beneath. When the depth is correct, the surface spreads weight across the base and remains more stable over time.

Gravel also supports natural drainage. Water passes through the spaces between stones and filters into the ground below rather than pooling on the surface.

This guide explains the correct gravel depths for common applications, with practical advice on preparing the base and managing drainage.

Recommended Gravel Depths for Different Applications

The correct depth of gravel depends on how the surface will be used, the ground conditions, and how water will drain through the construction. UK government guidance explains that gravel is considered a permeable surface for driveways. Planning permission is usually required if an impermeable driveway covers more than 5 m² and prevents water from draining to a permeable area [1].

Typical gravel construction layers include:

  • Decorative gravel surface of around 50 mm
  • Permeable sub-base of roughly 200 mm of open graded aggregate
  • Total construction depth of approximately 200-250 mm, including about 150 mm of compacted sub-base

Lighter surfaces, such as garden paths, can use shallower gravel layers because they carry minimal loads. A stable gravel layer is often used beneath slabs or concrete when installing shed bases or garden structures. Driveways and vehicle access areas require deeper construction to support the weight of cars and vans without movement.

Material choice also affects performance. MOT Type 1 contains fine particles that compact tightly but reduce permeability. Open-graded aggregates, such as Type 3 or 4/20, leave gaps between stones, allowing water to pass through the base while still providing structural support.

Build a Stable Base Beneath the Gravel

A properly prepared sub-base helps maintain the correct gravel depth and prevents the surface from shifting over time. Before installing aggregate layers, the ground should be cleared of materials that could affect stability, including topsoil, organic matter, or loose debris.

Approved Document C explains that ground used for construction should be reasonably free from substances that could affect stability. Where moisture or groundwater could affect the structure, suitable drainage may also be required [2].

Visit our guide on which aggregate should you use for your construction project? to help ensure the base material suits the demands of the project. For gravel paths and driveways, the sub-base forms the load-bearing foundation. Using the correct aggregate and compacting it properly helps distribute weight across the ground and reduce settlement.

When preparing a sub-base:

  • Remove topsoil and organic material before laying aggregate.
  • Install a compacted crushed aggregate layer to create a stable platform.
  • Compact the base in stages using a plate compactor.
  • Check levels before installing the surface gravel layer.

These steps help maintain consistent gravel depth and reduce movement once the surface begins carrying traffic.

Why Gravel Helps Water Drain Naturally

Different decorative gravel types are often used for paths and driveways because they allow rainwater to pass through the surface rather than running directly into drains.

The Royal Horticultural Society (RHS) notes that hard landscaping materials such as paving, concrete, and tarmac can increase rainwater runoff by up to 50%, which can contribute to localised flooding in built-up areas [3].

Gravel reduces this effect because water can filter through the gaps between stones and soak into the ground beneath. However, the depth of gravel and the soil conditions below both influence how effectively the surface drains.

For example:

  • Clay soils drain slowly and may require deeper gravel layers.
  • Sandy soils drain quickly and may need less base buildup.
  • Sloped ground may require edging to prevent gravel movement.

Considering these conditions helps ensure the gravel layer supports both drainage and long-term surface stability.

Practical Tips for DIYers & Contractors

Installing gravel at the correct depth requires careful preparation before materials are delivered. Measuring the area and calculating the volume of aggregate helps ensure the finished surface reaches the intended depth across the entire site.

Many landscaping projects combine gravel preparation with other groundwork, particularly when working on DIY Concrete projects. However, Planning Portal guidance explains that driveways made from permeable materials, such as gravel, normally do not require planning permission. This is, provided rainwater can drain naturally into the ground or into nearby borders [4].

When planning the installation, contractors also consider the grading and aggregate size, as these factors affect how stable the surface feels underfoot or under vehicle loads. Tools such as our concrete volume calculator can help estimate materials when preparing bases for slabs or foundations.

Key preparation steps include:

  • Measure the area and calculate the required gravel volume.
  • Excavate deep enough for the sub-base and gravel layers.
  • Install edging to prevent gravel from spreading beyond the surface.
  • Compact each layer thoroughly before adding the next.

These steps help maintain consistent gravel depth and ensure the finished surface performs reliably.

Get the Base Right Before You Lay Gravel

Getting the depth right from the start helps prevent problems such as rutting, shifting, or poor drainage later on. In most projects, garden paths require 50 to 75 mm of gravel, while driveways and vehicle access areas typically need 100 to 150 mm or more installed over a compacted sub-base.

Wright Readymix supplies reliable bulk bag aggregates and gravel suitable for paths, driveways, and base preparation across domestic and commercial projects. The team can advise on the most suitable materials for the ground conditions and intended use.

Call 0117 958 2090 or get in touch to discuss the right gravel for your project and arrange delivery.

External Sources

[1] GOV.UK, Ministry of Housing, Communities & Local Government (2018 to 2021), Guidance on the Permeable Surfacing of Front Gardens: https://www.gov.uk/government/publications/permeable-surfacing-of-front-gardens-guidance/guidance-on-the-permeable-surfacing-of-front-gardens

[2] GOV.UK, Ministry of Housing, Communities and Local Government, Ministry of Housing, Communities & Local Government (2018 to 2021), Site Preparation and Resistance to Contaminants and Moisture: Approved Document C: https://www.gov.uk/government/publications/site-preparation-and-resistance-to-contaminates-and-moisture-approved-document-c

[3] The Royal Horticultural Society (RHS), Front Gardens: Permeable Paving: https://www.rhs.org.uk/garden-design/permeable-paving

[4] Planning Portal, Paving Your Front Garden: https://www.planningportal.co.uk/permission/common-projects/paving-your-front-garden/planning-permission

Read more