What Are Preliminaries in Construction? Costs & Examples (UK Guide)
Preliminaries are the indirect costs in a UK construction project — site setup, health and safety, project management, insurance, welfare facilities and temporary utilities — that enable the work to happen but aren’t part of the building itself. They typically account for 5–15% of total project cost, depending on site complexity, project size and duration.
This guide explains what’s included in preliminaries, how much they cost, and how to manage them properly so they don’t catch you out mid-project.
What’s included in preliminaries?
The specifics vary by project, but most UK building contracts include the following categories under preliminaries.
Site setup
Clearing the site, establishing access routes, parking arrangements, and fencing or hoarding to secure the site against trespassers and theft. On busy or public-facing sites this can also include CCTV, lighting and gated access.
Health and safety
Personal protective equipment, hazard signage, first-aid provision, and welfare facilities (toilets, washing stations, rest areas). Compliance with Health and Safety Executive (HSE) requirements is mandatory on UK sites — particularly larger or public-facing projects under the CDM Regulations 2015.
Project management and administration
Contract drafting and administration, programme scheduling, coordination of subcontractors and suppliers, and progress meetings with the client and design team. This is the layer that keeps everything moving — covered in more depth in our guide to what a building contractor does.
Permits, licences and surveys
Planning permission applications, Building Regulations submissions and inspections, structural surveys, environmental surveys, party wall agreements, and any local council permits required (for example, partial road closures for deliveries).
Temporary utilities
Power supply (mains connection or generator), water supply for drinking and trades, and sanitary facilities. On longer projects these can run for many months and add up substantially.
Insurance
Public liability insurance (typically £2–5 million), employer’s liability insurance, contract works insurance covering materials and partial structures during the build, and professional indemnity cover for any design responsibility carried by the contractor.
A seventh category — waste disposal and environmental management (skip hire, recycling, dust and noise control) — is sometimes itemised separately and sometimes folded into site setup, depending on the contractor. Worth confirming which approach your quote uses.
How much do preliminaries cost?
Preliminaries on UK residential and commercial construction projects typically account for 5–15% of total project cost. Where in that range a specific project falls depends on four main factors:
- Project size — smaller jobs carry higher percentages because fixed costs (insurance, supervision, welfare provision) make up a bigger share of the total
- Site complexity — restricted access, conservation areas, listed buildings, and public-facing sites all push preliminaries higher
- Project duration — longer programmes accumulate more weeks of skip hire, security, scaffolding and welfare costs
- Location — urban sites with restricted access and parking often need additional measures (traffic management, road closures, time-restricted deliveries)
Worked examples
The table below shows what 5%, 10% and 15% preliminaries look like across typical UK project values.
| Project value | Simple site (5%) | Typical site (10%) | Complex / restricted site (15%) |
|---|---|---|---|
| £50,000 | £2,500 | £5,000 | £7,500 |
| £100,000 | £5,000 | £10,000 | £15,000 |
| £250,000 | £12,500 | £25,000 | £37,500 |
| £500,000 | £25,000 | £50,000 | £75,000 |
These figures cover the preliminary items themselves. They’re separate from the contingency you should hold for unforeseen issues during the build (typically a further 10–15% of project cost).
Where preliminaries sit in the overall budget
Preliminaries are one of five main cost categories on most construction projects. The table below shows typical proportions for UK residential work.
| Cost category | Typical share of total budget |
|---|---|
| Preliminaries | 5–15% |
| Labour and subcontractors | 30–40% |
| Materials | 30–40% |
| Professional fees (architect, engineer, surveys) | 5–10% |
| Contingency | 5–10% |
The percentages are indicative and shift by project type. Heritage and listed building work tends to push preliminaries and professional fees higher; volume new-build sees lower preliminaries due to economies of scale. (Source: BCIS benchmarking data and NRM2 measurement standards.)
Why preliminaries matter (and why they’re often missed)
Three reasons preliminaries deserve serious attention from clients:
Cost transparency
When preliminaries are bundled into a single lump sum on a quote, you can’t see what you’re paying for or compare quotes meaningfully. Itemised preliminaries — fencing, scaffolding, welfare, insurance — let you spot underpricing, identify omissions, and challenge anything that looks off. A reputable contractor should present them as line items, not bury them in a headline figure. We’ve covered this distinction in more depth in our guide to quality builders versus budget builders.
Risk and compliance
Many preliminaries — particularly health and safety provisions and insurance — exist because they’re legally required, not because the contractor wants to bill for them. Cutting corners on PPE, signage, welfare facilities or HSE-compliant fencing exposes everyone on site to physical risk, and exposes both contractor and client to legal and financial consequences. Under the CDM Regulations 2015, the client carries specific duties on construction projects. These aren’t optional.
Project flow
Most expensive delays on construction sites trace back to weak preliminaries. Trades can’t start because access isn’t ready. Materials can’t be delivered because the site isn’t set up. Inspections fail because permits weren’t filed. Strong preliminaries pay for themselves by preventing the downtime that small contractors charge for and large contractors absorb into next month’s invoice — either way, the client pays.
Illustrative example
The following scenario is illustrative — not a specific project — but reflects realistic figures for the type of work and location described.
A homeowner planning a £120,000 kitchen extension in central Oxford finds that preliminaries for their project come to £14,000, towards the higher end of the typical range. The drivers:
- The site sits next to a busy pedestrian walkway, requiring full hoarding rather than standard fencing
- The access road needs a partial closure permit for skip and material deliveries
- The property is in a conservation area, triggering additional planning conditions and surveys
- Site welfare for a four-month programme runs to several thousand pounds across portable toilets, washing facilities and a small welfare cabin
Itemising these costs at quote stage means the homeowner budgets £14,000 alongside the £106,000 for materials, labour and finishes — plus a separate 10% contingency. Without that breakdown, the same homeowner might have signed a £120,000 lump-sum contract assuming everything was included, then found themselves £14,000 short at first-fix.
How to manage preliminaries (for clients)
Six practical points for keeping preliminaries under control:
- Always request itemised quotes. Lump-sum preliminaries hide both genuine costs and missing scope. If a contractor won’t break them down, that’s information about the contractor.
- Plan permit applications early. Planning permission can take 8 weeks; some council permits longer. Submitting late means waiting at the start of your programme rather than during it.
- Hold a 5–10% contingency on top of the preliminaries budget. Site conditions surprise. Programmes extend. Permits get rejected and resubmitted. A contingency separate from the main project contingency gives you flexibility.
- Confirm in writing who’s responsible for what. If you’re supplying any preliminary items yourself — PPE, welfare, skip hire — document it. Assumptions cause disputes.
- Document scope changes immediately. Any change to the project — adding a room, relocating an extension — may push preliminaries up. Capture the cost impact at the point of change, not at the end of the job.
- Review preliminary spend at site meetings. If skip hire was budgeted for six weeks and you’re at week eight, somebody needs to flag it. Regular reviews prevent end-of-project shocks.
For a comprehensive checklist covering preliminaries and the broader planning process, see our free construction planning checklist.
Frequently asked questions
How much do preliminaries cost on a UK construction project?
Preliminaries typically account for 5–15% of total project cost on UK residential and commercial work. On a £100,000 project that’s £5,000–£15,000; on a £500,000 project, £25,000–£75,000. Smaller, complex, or restricted sites sit at the higher end; larger or simpler sites at the lower end.
What’s the difference between preliminaries and contingency?
Preliminaries are known costs for project enablement — site setup, insurance, welfare, project management — that you budget for upfront. Contingency is a separate fund (usually 10–15% of project cost) held back to cover genuinely unforeseen issues during the build. They serve different purposes and shouldn’t be conflated. Both are needed.
Why are preliminaries sometimes not shown separately on a quote?
Some contractors bundle preliminaries into their headline price for simplicity. While this can produce a cleaner-looking quote, it makes meaningful comparison between contractors much harder and obscures whether items have been missed. Always request an itemised breakdown.
Can I supply some preliminary items myself to save money?
Sometimes — for example, if you have a long-term skip hire arrangement or can supply PPE through another business. Discuss this with your contractor at quote stage so responsibilities are clear in the contract. Don’t assume you can supply items unilaterally; some preliminaries (HSE-compliant signage, certified scaffolding) need to meet specific standards the contractor is responsible for.
Do preliminaries change if the project scope changes mid-build?
Yes. Adding rooms, relocating elements, or changing materials can affect site setup, programme length, additional surveys, and insurance cover. A well-drafted contract sets out a variations procedure that captures these cost impacts in writing as changes are agreed — not at the end of the project.
Are preliminaries the same on every project?
No. They vary substantially based on site complexity, location, project duration and project type. A new build on an open rural plot will have different preliminaries to a renovation in a city centre conservation area. The 5–15% range is indicative; expect your specific project to sit somewhere within it based on its conditions.
