What Information Should You Have Before Requesting a Groundworks Quote?

Before requesting a groundworks quote, you should ideally have:

• Building Regulations drawings (or equivalent tender-ready design)
• Ground investigation report
• Foundation design
• Drainage layout
• Site access information
• Existing utility information
• Programme
• Clear scope of works

Incomplete information forces contractors to price risk. You then either receive a high quote padded for every eventuality, or a low quote that excludes critical items and generates variations later. Neither outcome helps the project.

This guide sets out what to gather before approaching groundworks contractors or commercial groundworks teams — so quotations are accurate, comparable and commercially useful. For how the wider package is planned, see Planning a Groundworks Package for a Commercial Development.

Provide the full postal address with postcode. If the site is hard to identify from the street, add a what3words location or a marked-up location plan.

Why this matters:

• Travel distance for plant and materials affects prelims and mobilisation
• Local ground conditions, flood risk and planning constraints vary by area
• Access routes — low bridges, narrow lanes, weight limits — change logistics and cost
• Building Control expectations can differ between authorities

What contractors need:

• Full postal address with postcode
• OS grid reference if available
• Site location plan (1:1250 or 1:2500)
• Directions highlighting access constraints
• Nearest landmark or notable junction where useful

Drawings are the single most important document in a groundworks quotation pack. Without them, contractors are pricing blind.

The minimum drawing set should include:

• Site layout plan — building position relative to boundaries, existing structures and site features
• Floor plans at 1:50 or 1:100 — internal layout and dimensions
• Elevations — finished ground levels and floor levels
• Section drawings — foundation depths, construction build-ups and ground levels
• Drainage layout — proposed runs, inspection chambers and connections
• Services plan — incoming utilities and known existing services

Where available, also issue the structural engineer's drawings for foundation design, reinforcement and loads. A groundworker should not have to interpret planning drawings to price foundation work. If you are seeking prices, drawings should be at Building Regulations stage or equivalent.

Issuing concept sketches as tender drawings. Vague sketches produce vague pricing. Contractors either load risk or exclude work. You cannot compare those returns fairly, and variations become almost inevitable once design firms up.

Key points:

• Foundation type and depth follow structural requirements and ground conditions
• Drainage must align with building footprint and finished floor levels
• Setting-out dimensions must be clear — positioning errors are expensive to correct

Ground conditions are the largest pricing variable on most groundworks packages. Without a proper site investigation, contractors have no reliable basis for foundation rates.

You should ideally hold:

• Desk study — historical maps, mining records and environmental data
• Site walkover — visible features, vegetation, existing structures and access
• Intrusive investigation — trial pits or boreholes for soil types, water table, contamination, bearing capacity and depth to competent strata
• Laboratory testing — classification, strength, contamination, sulfate content and volume-change potential where clay is present

Ground conditions determine foundation design. Chalk, clay and made ground demand different solutions. For investigation scope and sequencing, see ground investigation services. Where shallow foundations are unsuitable, mini piling or other piled options may follow from the GI and structural design — see Mini Piling vs Traditional Foundations.

Why this matters. Without GI, contractors typically over-specify to protect themselves, under-specify and create structural risk, or build large contingencies for unexpected ground. You fund that uncertainty either in the tender price or through later variations.

Allow time for investigation. A borehole package often needs two to three weeks for results before foundation design and tender can proceed on firm information.

Optional download — Groundworks Quote Preparation Checklist (PDF). A one-page checklist covering drawings, GI, foundation design, drainage, access, utilities, programme and scope helps the project team confirm readiness before invitations to tender go out. Keep a shared copy with the tender pack so every contractor prices from the same baseline.

Groundworks form the interface between the ground and the building above. Contractors need the structural demands on the foundations, not only a building outline.

What contractors need:

• Structural engineer's foundation design — type, depth, width and reinforcement
• Column loads and point-load positions
• Wall loading details
• Basement or undercroft requirements
• Temporary works requirements during construction
• Structural openings or transfer structures affecting the substructure

A steel-framed building with point loads needs a different foundation solution to masonry on strip footings. Foundation contractors price from design information — not from assumptions about the frame above.

Programme directly affects how contractors price labour, plant and sequencing.

• Proposed start date
• Required groundworks completion date
• Key milestone dates
• Whether work can be phased
• Periods when work cannot take place — restricted hours, school holidays, events
• Delivery dates for SIPs, timber frame or other prefabricated elements where relevant

Key points:

• Plant, labour and materials often need booking weeks or months ahead
• Out-of-hours or weekend working to hit a tight programme costs more
• Groundworks delay has a knock-on effect on every following trade — especially where prefabricated components are programmed for delivery

Issuing an aggressive programme with no float. Tight programmes with no slack become stressful and expensive when weather, utilities or ground conditions intervene. State the real constraints — do not invent an optimistic end date and expect contractors to absorb the risk silently.

How plant and materials get onto site — and how spoil leaves — is a core pricing input, not a site detail to sort later.

What contractors need:

• Vehicle access width and height
• Weight restrictions on approach roads
• Whether a concrete mixer or aggregate lorry can reach the pour or stockpile area
• Hardstanding for plant and site accommodation
• Turning circles for delivery vehicles
• Neighbour access rights or shared access requirements
• Site storage space for materials and spoil
• Waste management and disposal arrangements
• Restricted working hours — including planning conditions

Why this matters. If a 32-tonne mixer cannot access the pour, concrete must be pumped or transferred — both add cost. No spoil storage means higher muck-away frequency. Restricted hours extend duration and prelims. Weight-restricted bridges or roads often force double-handling of aggregates in smaller vehicles, which lengthens programme and increases haulage cost.

Underground services are among the most common sources of delay, damage and variation during excavation.

• Utility plans for water, gas, electricity, telecoms and drainage
• CCTV survey results for existing drainage — condition, position, depth and invert levels
• Meter locations and service entry points
• Records of private drainage or services on site
• Any diversions already agreed with utility providers

Key points:

• Unknown services force hand digging, on-site location surveys, or unacceptable strike risk
• Drainage invert levels are critical — new runs must connect with correct fall
• Hitting a buried service is a safety issue as well as a cost and programme issue

Drainage is often the most complex and variation-prone element of a groundworks package. Unclear drainage design is a frequent cause of mid-contract redesign.

What contractors need:

• Proposed drainage layout — runs, gradients and connection points
• Design calculations — flow rates and pipe sizing
• Foul and surface water requirements, including sewer connections
• SuDS requirements
• Soakaway design where applicable
• Pumping station requirements if levels demand it
• Existing connection details and invert levels
• Testing requirements — air test or water test — before backfilling

Building Control expects drainage to be tested before backfilling. Contractors need the test method in the tender information so it is programmed and priced. For system design and installation context, see the construction drainage guides; for soakaways specifically, see soakaway installation.

Leaving soakaway or SuDS design unresolved at tender. If infiltration rates, attenuation volume or adoption status are still open, contractors cannot price drainage with confidence. You will compare returns built on different assumptions.

Planning permissions often carry conditions that directly constrain groundworks. Relevant conditions should be identified — and preferably discharged — before work is priced as ready to start.

• Tree protection — Root Protection Areas, fencing and arboricultural supervision
• Archaeology — watching briefs or excavation requirements
• Contaminated land — remediation, validation or verification
• Ecological constraints — seasonal working and protected species
• Hours of operation
• Construction management plan requirements — dust, noise and traffic
• CEMP requirements where specified

Why this matters. Undischarged conditions can stop a start on site or force more expensive working methods. Tree Protection Orders commonly drive deeper foundations, root barriers or a change of foundation type — all of which belong in the tender pack, not as a surprise after award.

New or upgraded utility connections are a substantial part of many groundworks packages and are frequently under-briefed at pricing stage.

• Water connection point and requirements
• Gas connection point if required
• Electricity supply point and capacity
• Telecoms connection requirements
• Off-site works — road openings, trenching, highway permits
• Utility provider quotes for connection charges where available

Statutory undertakers control specifications and lead-in times. A groundworks contractor cannot trench for a gas main without provider approval on design. Connection quotations often take around four weeks once drawings and information are with the utility — start early.

Mismatched scope is one of the most common causes of dispute after award. Define inclusions and exclusions before you request quotes.

• Extent of excavation — how much, how deep, where
• Site clearance and enabling works responsibility
• Spoil disposal responsibility and cost
• Materials — supply and fix, or labour only
• Foundation type — strip, trench fill, piled, raft or pad
• Completion level — to DPC, to slab, or to finished ground level
• Backfilling responsibility
• Plant provision — excavators, concrete pumps and other equipment
• Finishing standard
• Demolition or specialist subcontracted works, including piling

Comparing quotes that price different scopes. One contractor may price excavation to formation only. Another may price through to DPC including drainage and backfill. Without a written scope boundary, the cheaper return is often the less complete one.

The variation trap. Incomplete drawings and vague scope make variations almost inevitable. Each variation adds cost and programme time, and Building Control approvals can be affected if works proceed without proper design sign-off.

Optional download — Groundworks Tender Information Checklist (Excel). A shared spreadsheet listing every drawing, report, assumption and exclusion issued with the invitation to tender helps keep returns comparable. Use it as a living register: issue revision, date received, and whether the item is priced or provisional.

Groundworks quotations vary because contractors are rarely pricing identical information, identical risk or identical scope — even when they receive the same email. From a contractor's perspective, price differences usually come from how unknowns are treated.

A contractor who has walked the access route, read the GI and marked every exclusion will often look more expensive than one pricing from a site address and a planning drawing. The cheaper return may simply have left more risk with you.

For indicative budgeting before tender, the groundworks cost calculator and groundworks cost guide can help frame expectations — they are not a substitute for a priced package based on drawings and GI.

Use this checklist before requesting quotations. Issue the same pack to every contractor so returns are comparable.

Complete tender information improves price accuracy, reduces variations, supports resource planning and lowers commercial risk.

Approach groundworks contractors when there is something concrete to price — not when design is still conceptual.

Do approach contractors when you have:

• Building Regulations drawings (or equivalent)
• Completed ground investigation
• Structural engineer's foundation designs
• Relevant planning conditions identified or discharged
• An agreed drainage strategy

Do not approach contractors when:

• You are still at concept / planning-drawing stage only
• Ground conditions have not been investigated
• Drainage design is unknown
• Scope of works is still unclear

Early contractor discussion can still be useful for buildability — but treat it as advice, not as a formal competitive quote. Formal quotations belong to a defined information pack.

When you do go out to tender, obtaining quotations from vetted commercial contractors helps produce more consistent pricing and a clearer view of delivery capability. The Mainline Network lists groundworks contractors so clients can shortlist firms with relevant commercial experience rather than comparing returns from businesses of very different capacity and risk appetite.

Building Control approval. Foundation work requires Building Control approval. Confirm the approval route — Local Authority Building Control, a registered building control approver, or arrangements agreed with the contractor — before work starts.

Contracts and payment terms. Once you have chosen a contractor, put a written contract in place covering scope, payment terms (including stage payments and retention), variations procedure, programme, insurance and defects liability. Do not rely on verbal agreements.

Expect residual unknowns. Even with good preparation, groundworks can reveal issues. A competent contractor will stop, assess, price the change and seek approval before continuing. When comparing quotes, weigh the quality of questions and clarity of exclusions as carefully as the headline figure — thorough tenderers are usually more professional on site.

This guide is a practical resource for developers, self-builders, commercial clients and project managers seeking accurate, comparable groundworks quotations.

It reflects industry practice for tender information and pricing. It does not constitute legal, structural or professional advice. Always seek advice from qualified engineers, surveyors or legal professionals for project-specific requirements.