UK construction glossary

A Bill of Quantities (BoQ) is a structured document listing measured quantities of every item of work required to build a project, used at tender stage to allow contractors to price like-for-like.

A compensation event is the NEC-contract equivalent of a variation — a defined event entitling the contractor to additional cost, time, or both, processed through a structured notification-and-quotation system.

Contingency is a cost reserve held in the project budget to cover risks that may materialise during the project. UK consultancies typically distinguish design contingency, construction contingency, and employer's contingency.

A cost plan is the consultancy's structured estimate of project cost, developed and refined through the design stages. It sits at the heart of pre-construction commercial work, evolving from order-of-magnitude at Stage 0 to detailed at Stage 4.

The Defects Liability Period (DLP) is the period after Practical Completion during which the contractor remains responsible for remedying defects in the work. Typically 12 months on UK building contracts.

The final account is the agreed total cost of a construction project, reached at project closeout. It comprises the original contract sum plus all approved variations, provisional sum reconciliation, and final adjustments.

JCT (Joint Contracts Tribunal) is the most widely used family of UK construction contracts, particularly in private-sector building projects. JCT 2024 is the current edition.

NEC (New Engineering Contract) is a family of standard-form construction contracts used widely in UK public-sector and infrastructure projects. NEC4 is the current edition.

Out-turn cost is the final actual cost of a construction project at completion, including all variations, contingency drawdown, and provisional sum reconciliation. Locked at project closeout.

A PCSR — Project Cost Summary Report — is the monthly cost report at the heart of how UK construction consultancies report on project commercial position. Committed, anticipated, forecast, and out-turn cost, summarised by package.

Practical Completion (PC) is the contractual milestone at which the construction works are deemed substantially complete and the building is handed over to the client. It triggers retention release and the start of the defects liability period.

A Pre-Construction Services Agreement (PCSA) is a contract between client and contractor covering the contractor's services during the pre-construction phase of a two-stage tender — typically including design input, buildability advice, and target cost development.

A procurement package is a defined parcel of construction work let to a single sub-contractor or supplier. A typical UK building project has 20–60 packages covering everything from groundworks to floor finishes.

A provisional sum is an allowance included in the contract sum for work that cannot be fully specified at tender. The actual cost is established later and substituted for the allowance at final account.

The RIBA Plan of Work is the UK construction industry's framework for organising the design and delivery of building projects, structured into 8 stages from strategic definition (0) through to use (7).

RIBA Stage 4 — Technical Design — is the stage at which design is fully resolved, tender documents are prepared, and cost certainty is established before procurement begins.

An S-curve is a graphical representation of cumulative project spend over time, named for its characteristic S-shape: slow at the start, rapid in the middle, slow at the end.

Snagging is the process of identifying minor defects in completed building work — typically just before practical completion — so the contractor can remedy them before the building is handed over to the client.

A tender is the process of inviting contractors or sub-contractors to price a defined scope of work. The tender pack is the document set issued to tenderers — drawings, specification, BoQ, contract terms, programme — and the response is their priced proposal.

A valuation is the monthly assessment of work executed on a construction project, used to certify the contractor's next interim payment. The QS calculates the value of work in place; the certifier issues the payment certificate.

A variation is a change to the contracted scope of work after the contract has been signed. Under JCT it's a "variation"; under NEC it's a "compensation event". Both adjust cost and programme.