The short answer
Groundworks are the site preparation and below-ground construction needed before a building, extension, driveway or landscape structure can be built reliably. Depending on the project, they include clearance, setting out, excavation, foundations, drainage, service ducts, sub-bases and concrete preparation.
What is included in groundworks?
“Ground works” and “groundworks” usually describe the same construction activity. The important distinction is the written scope: not every contractor’s groundworks package includes every below-ground item. Ask where the package starts, where it ends and which design, approval and inspection responsibilities sit elsewhere.
- Site preparation: understand access, protect retained features and clear the agreed working area.
- Setting out: transfer positions and levels from the design to the site.
- Excavation: remove material to the required formation while controlling risks and spoil.
- Foundations: construct the specified support for the structure, subject to required inspections.
- Drainage and services: coordinate pipes, access chambers, ducts and their relationship with foundations.
- Slabs and external bases: prepare suitable layers, reinforcement and levels for the next construction stage.
Groundworks versus foundations
Foundations are one part of groundworks. A foundation transfers structural loads into suitable ground; the wider groundworks package may also manage water, access, formation levels and services. Paying attention only to the foundation trench can leave drainage conflicts or incorrect floor levels unresolved.
See our groundworks and foundations service for package scope, or the extension foundation guide for the questions that influence the designer’s choice.
The usual construction sequence
- Review the brief: confirm drawings, approvals, boundaries and the information still missing.
- Investigate the site: check levels, access, ground and buried services before choosing a method.
- Agree the scope: record quantities, assumptions, exclusions and inspection points.
- Prepare and excavate: set out, protect the site and manage excavation and waste safely.
- Inspect and construct: obtain required checks before pouring concrete or covering drainage.
- Record and hand over: retain relevant photographs, drainage routes and inspection information.
The order changes where temporary support, service diversions or ground improvement are needed. A construction programme should make those dependencies visible rather than promising the same sequence for every property.
How long do groundworks take?
There is no reliable standard duration for “groundworks”. A small paving base and an extension with deep foundations are not comparable. A programme needs the scope, quantities, access, inspections and ground information before a contractor can commit to dates.
Ask for separate allowances for mobilisation, excavation, inspections, drainage, concrete work and handover. Also ask which activities must wait: for example, foundation inspection before a pour or approval of a changed detail after unexpected ground is exposed. Weather, machine access and spoil collections can affect productive time without changing the measured area.
What affects the cost?
Depth and volume matter as well as area. Difficult access can change machine size and the number of movements needed to remove spoil. Trees, existing foundations, groundwater and shared drainage may add design or investigation requirements. A rate that excludes waste, concrete or drainage cannot be compared directly with a complete package.
Use the groundworks cost guide to structure a quotation and the excavation volume calculator for an initial quantity. Calculator outputs are planning aids, not structural designs or disposal instructions.
What we record during an A Jones groundworks survey
Our first site visit is used to replace assumptions with visible evidence. We record the route from the road to the work area, the narrowest access point, relevant thresholds and level changes, likely spoil-loading position, visible drainage and the relationship with nearby buildings, boundaries and retained trees. Drawings and statutory records are then checked against what can actually be seen on site.
| Evidence | Decision it informs |
|---|---|
| Access width, turns and loading point | Plant size, protection, haul route and spoil movements |
| Thresholds and measured level changes | Excavation, finished levels, falls and retaining needs |
| Visible drains, covers and water routes | Investigation, connection levels and construction sequence |
| Trees, boundaries and nearby structures | Design questions, temporary support and protection |
This record is not a ground investigation or structural design. It makes the next professional questions clearer and helps quotations state the same assumptions. Use the site-survey brief builder to collect the same evidence before contacting contractors.
Safety and inspection points
Excavations can collapse or undermine nearby structures. Planning support, access and protection is work for competent people, not a decision to make after someone enters a trench. HSE’s excavation guidance explains the principal risks. Its underground-services guidance covers planning and locating services before digging.
Agree Building Control and design-team inspection points before work starts. Do not cover work that needs checking. Foundation depth is site-specific: an online “minimum depth” does not account for the actual soil, trees, loading or neighbouring structures.
Prepare a useful contractor brief
Send the postcode, proposed work, current drawings, photographs, access width and known drainage information. Explain whether the property remains occupied, where materials can be delivered and which surfaces need reinstating. Make missing information explicit rather than asking several contractors to price different assumptions.
Our site-survey brief builder helps organise the first conversation. You can also review documented A Jones projects and our Surrey service areas before requesting a survey.
Frequently asked questions
Do groundworkers design foundations?
Construction and structural design are separate responsibilities unless a written appointment explicitly combines them. Confirm who provides the design and who can approve changes before excavation.
Does the quote include waste removal?
Not automatically. Ask what material, volume, loading and disposal are included and what happens if contamination or unexpected construction is found.
Can drainage be installed later?
Some work can be sequenced later, but routes, levels and connections should be coordinated early. Retrofitting a pipe through completed foundations or paving can cause avoidable disruption.
From the site
Groundworks in practice: before the surface goes back
The finished surface is only part of the job. A drainage package also needs the pipe route, levels, bedding, checks and reinstatement agreed. Our drainage and groundworks project shows the work behind the finish.
For an extension, check where the quote stops
One quote may end at the foundations; another may include drainage and the floor slab. Before comparing totals, ask whether each covers:
- Excavation, access protection, loading and removal of the agreed spoil.
- Foundations to the specified design, concrete and the required inspection stages.
- Drainage pipes, chambers, connections, checks and reinstatement.
- The oversite: which sub-base, membrane, insulation and concrete layers are included.
- How unexpected ground and extra quantities will be agreed and priced.
- Photographs and relevant inspection records before work is covered.
Use the groundworks quote comparison tool to record differences. This is a scope checklist, not a construction specification; the design and actual ground determine the work.
Planning locally? Read about our groundworks in Woking or our Guildford groundworks team, then send the postcode and a few photos to discuss your job.
Continue with the actual site
Related guides & services
Use the guide to frame the first questions, then compare them with the property’s ground, levels, access and drainage.
Check the site-specific details
General guidance cannot verify your ground, structure, drainage, permissions or site access. For statutory requirements, use the official Planning Portal, your local authority, Building Control and the relevant water company or designer.
