Quantity Surveying Glossary

For most students entering the profession, the Bill of Quantities (BoQ) is the single most important term to understand, because it underpins both measurement practice and contract administration. The BoQ is the document that turns design drawings into a priced schedule used for tendering, valuation and final account. Understanding how a BoQ is prepared – using NRM2 rules, organised into work sections, including provisional sums and prime cost sums – gives you the framework to understand almost every other term in this glossary. Once you understand the BoQ, the cost plan (the pre-tender budget tool) and the final account (the post-contract financial settlement) both follow logically. The NRM2 Measurement Guide explains the full BoQ preparation process step by step.

A cost plan is a pre-design estimate prepared under NRM1, structured by elements (substructure, superstructure, finishes, MEP, externals), and used by the client's QS team to control the budget during design development – typically from RIBA Stage 1 (Preparation and Brief) through to Stage 3 (Spatial Coordination). A Bill of Quantities is prepared under NRM2 after the design is sufficiently developed (RIBA Stage 4), is structured by work sections rather than elements, and is the document given to tendering contractors to price. The cost plan is an internal management tool; the BoQ is a contractual document. In practice, the QS prepares both – the cost plan at each design gate to keep the client informed, and the BoQ to obtain competitive tender prices. See the full guide to construction cost management for how these documents fit within the RIBA Plan of Work.

JCT (Joint Contracts Tribunal, 1931) is traditional, legally drafted, and used on approximately 70% of UK private-sector building projects – it is the default choice for commercial, residential, and retail construction. NEC (New Engineering Contract, now NEC4, published 1993 and updated 2017) takes a project-management approach, using plain English, early warning notices, and a collaborative risk register instead of adversarial contractual mechanisms; it dominates UK public sector infrastructure including Highways England, Network Rail, and HS2. The fundamental operational difference: under JCT, a contractor makes a loss and expense claim retrospectively; under NEC4, a contractor must notify a compensation event within 8 weeks or lose entitlement entirely. For a full side-by-side comparison see the JCT vs NEC guide.

BIM Level 2 (now formally referred to as ISO 19650 compliance) requires all project information to be produced, shared, and managed in a federated environment using a Common Data Environment (CDE). It has been mandatory on UK central government projects above the OJEU threshold since April 2016. For quantity surveyors, BIM Level 2 means that geometric models from architects and structural engineers can be used to assist with measurement – but NRM2 rules still govern how items must be described and grouped. 5D BIM takes this further by linking cost data directly to the 3D model, enabling real-time cost reporting and automated quantity extraction using software such as CostX, RIB iTWO, or Autodesk Quantity Takeoff. The learndirect Level 5 Diploma covers BIM fundamentals in the Digital Construction unit, ensuring graduates understand both the technology and its practical limits for QS work.

Both are allowances in a BoQ for work not fully defined at tender, but they differ in purpose. A provisional sum is used for work whose full extent is genuinely uncertain – for example, ground investigation works or complex specialist installations. NRM2 distinguishes between “defined” provisional sums (where the contractor is expected to programme for the work and include it in their overhead and profit calculations) and “undefined” provisional sums (where the contractor makes no programming allowance until instructed). A prime cost (PC) sum is a historic mechanism used for the supply of materials or goods by a nominated supplier – the “prime cost” being the net supply price before the main contractor's attendance and profit. Under modern procurement practice, PC sums are rarely used because nominated supplier arrangements create contractual complexity; provisional sums and performance specifications are preferred instead.

A fluctuation clause (also called an escalation clause) allows the contract sum to be adjusted to reflect changes in the cost of labour, materials, and other inputs during the construction period. JCT contracts contain three options: Option A (fixed price – no adjustment), Option B (labour and materials cost changes – limited adjustment based on defined fluctuation items), and Option C (formula adjustment – using RICS/BCIS price adjustment formulae). Most projects up to 18 months use Option A (fixed price), but on longer contracts – particularly those spanning significant inflationary periods, such as post-2021 UK construction – Option B or C provides important financial protection for contractors. The BCIS (Building Cost Information Service) publishes the tender price indices used in formula fluctuation calculations.

The RICS NRM suite is available from the RICS standards and guidance page. NRM1, NRM2, and NRM3 are available for purchase as printed books and PDF downloads from the RICS bookshop; RICS members receive a discount. Many university libraries and employer organisations hold institutional copies. For students on the learndirect QS Diploma, the key measurement rules are covered in the Measurement 1 and Measurement 2 units, which provide structured learning around the most commonly examined NRM2 work sections. The RICS also publishes free-to-access guidance notes and information papers on specific measurement topics – these are listed in the RICS Professional Standards section under Construction. For cost data, the BCIS (a subsidiary of RICS) provides subscription-based access to elemental cost analyses, tender price indices, and regional cost modifiers.

The two most widely referenced texts for QS terminology are Quantity Surveying Practice by Ivor Seeley (Palgrave Macmillan) and Willis's Practice and Procedure for the Quantity Surveyor by Allan Ashworth, Keith Hogg and Catherine Higgs (Wiley-Blackwell, 13th edition). For pure terminology reference, the RICS Black Book series and the BCIS Elemental Standard Form of Cost Analysis contain the most precise and current definitions used in professional practice. The RICS also publishes a Glossary of Construction Terms which is freely accessible on the RICS website. For contract-specific terminology, Keating on Construction Contracts (Sweet & Maxwell) is the legal authority, while the NEC4 Guidance Notes provide the definitive explanation of NEC-specific terms. Learndirect's QS Diploma curriculum references these sources throughout the 12 units of study. For those beginning their journey, the guide to becoming a quantity surveyor provides additional reading recommendations.