Preliminaries and General Items in Construction

Introduction

Preliminaries are the costs of running a construction project that cannot be attributed to specific measured items of permanent work. They cover everything from site management and welfare facilities to tower cranes, scaffolding, insurance, and waste disposal. On a typical UK project, preliminaries account for 10–15% of the contract sum — a significant budget line that the quantity surveyor must understand, price, monitor, and challenge throughout the project lifecycle.

Under RICS NRM 2, preliminaries are classified as Group 1: Preliminaries / General Conditions, separated from measured works in the bill of quantities to ensure consistent pricing and transparent cost management across the industry.

What Preliminaries Cover

NRM 2 Group 1 organises preliminaries into three broad categories. Employer’s requirements include insurances, bonds, warranties, building control fees, and any site constraints or compliance obligations imposed by the contract. Main contractor’s cost items cover the practical costs of running the site — management and staff, site establishment, temporary works, mechanical plant, cleaning, and waste removal. Information and requirements describe the project context (contract period, site conditions, access restrictions) that influences how the contractor prices the other items.

The most cost-significant items within a typical preliminaries breakdown are management and supervision (site manager, foreman, site-based QS), site establishment (offices, welfare facilities, storage compounds, security), mechanical plant (tower cranes, hoists, telehandlers), temporary works (scaffolding, hoardings, temporary roads, weather protection), temporary services (electricity, water, drainage), and cleaning and waste management (skip hire, dust suppression, final clean).

Fixed Charges vs. Time-Related Charges

NRM 2 requires contractors to distinguish between fixed charges and time-related charges within their preliminaries pricing. Fixed charges are one-off costs that do not vary with project duration — for example, site establishment (setting up offices, erecting hoardings), crane installation and dismantling, and final cleaning. Time-related charges are ongoing costs that increase proportionally with the contract period — site supervision, plant hire, scaffold hire, welfare facility running costs, and temporary services.

This distinction is critical for the QS because it determines how preliminaries are valued during interim payments and, importantly, how they are adjusted if the contract period changes. If the project is granted an extension of time, time-related preliminaries increase but fixed charges do not. A contractor who has front-loaded their fixed charges and under-priced time-related items will appear cheaper at tender but may submit inflated claims when delays occur.

How Preliminaries Are Priced

Contractors price preliminaries using one of three approaches. The most transparent is a detailed breakdown — each item priced individually with resource, duration, and rate stated (e.g., site manager: £1,200/week × 52 weeks = £62,400). Some contractors price on a percentage basis, applying a single percentage to the measured works total. Others submit a lump sum with minimal breakdown. The QS should always insist on a detailed breakdown at tender stage — it is the only way to verify whether the preliminaries are realistic and to value them accurately in interim certificates.

Typical preliminaries as a percentage of contract sum range from 10–15% for building projects, though this varies with project type, complexity, and duration. Short, intense projects (refurbishment, fit-out) tend to have higher preliminaries percentages because fixed establishment costs are spread over a smaller measured works value. Long-duration projects may have lower percentages but higher absolute costs.

Cost-Significant Items

Scaffolding is often the single largest preliminaries item, typically 3–5% of contract sum on medium-rise projects. It is priced as a fixed charge for erection and dismantling plus a time-related hire charge. The QS must track scaffold duration against the programme — if scaffolding remains erected longer than planned (due to delays or phasing changes), the cost escalates rapidly.

Tower cranes cost £8,000–£15,000 per month for hire alone, with additional costs for erection, dismantling, operator, and base construction. On multi-storey projects, the crane is often on the critical path — its removal date directly affects programme and cost. Site supervision (site manager, foreman, general foreman) typically represents £150,000–£250,000 per annum depending on project size. Site accommodation (offices, canteen, welfare) incurs both delivery/removal (fixed) and hire/running costs (time-related).

Valuing Preliminaries in Interim Payments

The QS values preliminaries at each interim certificate using one of three methods depending on contract arrangement and the nature of the item. Time-related items are valued pro rata to the programme period elapsed — if the contract is 12 months and 6 months have passed, 50% of time-related preliminaries are due. Fixed charge items are valued when the event occurs — site establishment costs are due once the site is set up, crane erection when the crane is erected, final clean when it is completed. Value-related items (less common) are valued pro rata to the percentage of measured work completed.

The QS should never simply apply a blanket percentage to the measured works value. Each item should be valued according to its nature, and the total checked against the contractor’s preliminaries breakdown submitted at tender.

Preliminaries Under Different Contract Forms

Under JCT contracts with quantities, preliminaries are priced separately in the BOQ as a distinct section, giving full transparency. Under NEC4, preliminaries are embedded within the activity schedule (Option A) or form part of Defined Cost (Options C/D/E) — the QS must understand where preliminaries sit within the pricing structure to value them correctly. Under design and build contracts, preliminaries are typically absorbed into the contractor’s lump sum price with limited breakdown visibility, making tender analysis and interim valuation more challenging.

Common Mistakes

Not checking preliminaries against the programme. A contractor pricing 12 months of supervision on a 15-month programme is either making an error or planning to under-resource the site. The QS must cross-reference every time-related item against the contract period.

Allowing front-loading. Contractors sometimes inflate fixed charges and early preliminaries items to improve cash flow in the first few months. The QS should compare the preliminaries breakdown against industry benchmarks and challenge disproportionate early payments.

Not adjusting for extensions of time. When an EOT is granted, time-related preliminaries increase. The QS must recalculate and advise the client on the cost implication — a common source of claims that catches junior staff off guard.

Double-counting with measured rates. Some items can appear in both preliminaries and measured works — for example, scaffolding priced in preliminaries but also included within brickwork rates. The QS must check for duplication at tender analysis.

Practical Tips

Always request a detailed preliminaries breakdown at tender. A lump sum figure is not sufficient for cost management purposes. Insist on resource, duration, and rate for every item.

Maintain a separate preliminaries tracker. Track each item independently, comparing actual spend or elapsed time against the tender allowance. This is particularly important for high-value items like scaffolding, cranes, and supervision.

Challenge scaffold and crane durations. These are the items most likely to overrun. Compare the contractor’s programme against the priced durations and flag any discrepancy.

Adjust for EOT promptly. When an extension of time is granted, update the preliminaries forecast immediately. Do not wait until the final account to address time-related cost increases.

APC Relevance

Preliminaries sit within the RICS APC competencies of Quantification and Costing (understanding how preliminaries are measured, priced, and valued) and Contract Practice (how different contract forms treat preliminaries, and how extensions of time affect costs). APC candidates should be able to explain the fixed vs. time-related distinction, describe how preliminaries are valued in interim certificates, and discuss the risks of front-loading.

Further Reading on ProQS

For more on related QS skills, see these ProQS articles:

Elemental Cost Planning — how preliminaries are estimated and allocated within cost plans at each RIBA stage.

Contractor Estimating and Tender Pricing — how contractors build up their preliminaries pricing from first principles.

NRM 2 Practical Measurement Guide — the measurement framework that governs how preliminaries are described and structured.

Interim Valuations and Payment Applications — how preliminaries are valued within the monthly interim payment process.

Key References

RICS NRM 2: Detailed Measurement for Building Works — the standard measurement framework including Group 1 preliminaries classification.

Designing Buildings Wiki: Preliminaries — comprehensive reference covering types, pricing, and management of preliminaries.

RICS: Interim Valuations and Payment — professional guidance on valuing preliminaries within interim certificates.

JCT Contracts — the Joint Contracts Tribunal standard forms governing preliminaries pricing in BOQs.

NEC Contracts — the NEC4 suite including activity schedule and defined cost treatment of preliminaries.