NRM2 item coding is the codification system the RICS sets out for bills of quantities (BoQs). Each item gets a hierarchical code that identifies the project, the bill, the element of the building and, at the finest levels, the component and subcomponent you are measuring. Levels 2 to 4 are fixed by NRM1, and levels 5 and 6 are yours to define. This guide explains how the code is built, walks through a worked example, and covers the mistakes that make a coded BoQ hard to reconcile with the cost plan.
TL;DR
- NRM2 codification runs from level 0 (project) to level 6 (subcomponent), and the code is read left to right from the general to the specific.
- In an elemental BoQ, levels 2 to 4 (group element, element, sub-element) come from NRM1. Levels 5 and 6 are user-defined.
- You choose one of three breakdown structures first: elemental, work section or works package. The structure decides how the code is built.
- The most common failure is a BoQ code that does not match the cost plan code, so cost reconciliation turns into manual re-mapping.
- Keep your level 5 and 6 codes short, distinct and used the same way across the whole BoQ.
Table of Contents
- What NRM2 item coding is for
- The seven levels of an NRM2 code
- A worked example: pile cap excavation
- Choose the breakdown structure before you code
- How to apply a code, step by step
- Common coding mistakes and how to avoid them
- How NRM2 coding differs from other UK measurement standards
- Applying the coding to a small project
- Where software fits
- FAQ
- Sources
What NRM2 item coding is for
NRM2 is the RICS standard of detailed rules for measuring and describing building works so that you can prepare a BoQ or a quantified schedule of works. It sits alongside NRM1 (cost planning) and NRM3 (maintenance). The measurement rules tell you what to measure and how to describe it. The coding tells you where each measured item lives in the project's structure.
According to the RICS guidance note on NRM2 (2nd edition, effective 1 December 2021), codification is used to identify and organise building components and subcomponents logically. The aim is better cost management, cost control and information retrieval across the life of the project.
In practice, a good code does three jobs:
- Identifies each line uniquely, so a rate, a revision or a query can point to one item and no other.
- Groups lines so that totals roll up to elements and group elements.
- Connects the BoQ to the cost plan, so that variances can be traced between estimate, tender and final account.
If you want the wider background to the standard first, our explainer on NRM2 and the RICS standard for measuring building works covers what the rules include and who uses them.
The seven levels of an NRM2 code
The RICS guidance describes a hierarchical code running from level 0 to level 6. Each level adds detail to the one before it.
| Level | What it identifies | Who defines it (elemental BoQ) |
|---|---|---|
| 0 | Project | You (project number or reference) |
| 1 | Bill number | You |
| 2 | Group element | NRM1 |
| 3 | Element | NRM1 |
| 4 | Sub-element | NRM1 |
| 5 | Component | User-defined |
| 6 | Subcomponent | User-defined |
This split, with NRM1 setting levels 2 to 4 and the user setting levels 5 and 6, is set out in the RICS guidance.
The practical consequence is useful. Because levels 2 to 4 are shared with NRM1, an elemental BoQ and an NRM1 cost plan speak the same language down to sub-element. Your own judgement only comes in at levels 5 and 6, where you decide how finely to split the work.
Reading a code left to right
A code is read like an address: project, then bill, then element, then the detail. You can stop reading at any level and still know where the item sits. That is what makes roll-ups possible. A total at level 3 is simply every line sharing the same first four segments.
A worked example: pile cap excavation
The RICS guidance gives a worked code for excavation of a pile cap: DPB27-3.1.1.2.1.1. Here is how it breaks down:
| Segment | Level | Meaning |
|---|---|---|
| DPB27 | 0 | The project |
| 3 | 1 | The bill number |
| 1 | 2 | Substructure (group element) |
| 1 | 3 | Foundations (element) |
| 2 | 4 | Piled foundations (sub-element) |
| 1 | 5 | Pile cap (component) |
| 1 | 6 | Excavation (subcomponent) |
The example comes from the RICS guidance note. Two points are worth taking from it.
First, the code says what the item is and where it belongs, but not how much of it there is or in what unit. The unit comes from the measurement rule for the relevant work section in NRM2, and the description carries the detail the rule requires. Some rules ask for dimensioned descriptions and proprietary references, for example for metal fixings and fastenings, as the published NRM2 extract shows.
Second, levels 5 and 6 here (pile cap, excavation) are the only parts a surveyor chose. Everything before them follows from the structure of the project and from NRM1. If another surveyor on your team codes a pile cap as component 3 on the next job, you have already made reconciliation harder. Decide your level 5 and 6 conventions once and write them down.
Choose the breakdown structure before you code
Codes are only meaningful relative to a structure. The RICS guidance sets out three principal breakdown structures for an NRM2 BoQ:
- Elemental: ordered by group elements, which mirror the NRM1 cost plan.
- Work section: divided into the work sections defined in Part 3 of NRM2.
- Works package: defined by the client or contractor to suit how the job will be procured and let.
The RICS guidance is the source for these three options.
When each tends to fit
Elemental suits projects where the cost plan is the control document and the client wants to see where the money goes by building element. Coding is the most direct, because levels 2 to 4 are predefined.
Work section suits a BoQ that will be priced by trades, because the sections follow the order a contractor or subcontractor thinks in. Your code needs to reflect the work section rather than the NRM1 element, so confirm the convention you are using before you start measuring.
Works package suits procurement routes where the client or contractor has already split the job into packages. The package structure comes from them, so agree it in writing before you code.
If you are unsure which layout suits the job, our piece on which bill of quantities format to use goes through the trade-offs.
How to apply a code, step by step
The RICS guidance supports a straightforward order of work. Here it is as a checklist you can use on any BoQ.
- Fix the breakdown structure. Decide elemental, work section or works package with the client or contractor, and record it.
- Set levels 0 and 1. Use the project reference and the bill number.
- Map each item to NRM1 levels 2 to 4. For an elemental BoQ, find the group element, element and sub-element the item belongs to.
- Define level 5. Name the component, for example a pile cap, a strip footing or a ground-floor slab, and give it a code.
- Define level 6. Name the subcomponent, such as excavation, formwork, reinforcement or concrete, and give it a code.
- Write the description and unit from the NRM2 rule. The measurement rule for that work section tells you what the description must contain and which unit applies.
- Record the source. Note the drawing and revision the quantity came from, so any query can be traced.
Step 3 is where most of the thinking sits. A wall can plausibly belong to more than one element if you are not careful about the boundary, so check the NRM1 element definitions rather than coding from memory.
Keeping a user-defined convention
Since levels 5 and 6 are yours, a short internal convention pays for itself. A simple approach, offered as an illustration and not as an NRM2 requirement:
- Keep a list of components you use often, each with a fixed number.
- Keep a list of subcomponents, again with fixed numbers, so that excavation is always the same digit wherever it appears.
- Never reuse a number for something different on another job within the same practice.
Then a code like the pile cap example reads the same way on every project you do.
Common coding mistakes and how to avoid them
The RICS guidance points to a few areas where codification goes wrong.
The BoQ code does not match the cost plan
This is the main one. If the cost plan is codified one way and the BoQ another, reconciling the two becomes a manual exercise. Agree the codification at the start, and keep the same group elements, elements and sub-elements in both documents.
The wrong breakdown structure for the job
Mixing elemental and work section logic inside one BoQ produces totals that do not roll up. Pick one structure for the bill and keep to it. If a client later asks for a different view, produce it as a separate output and do not re-code the original.
Unclear level 5 and 6 codes
User-defined levels should be clear, distinct and applied consistently across the whole BoQ. Two components with near-identical names and neighbouring numbers are an invitation for a mis-keyed line.
Codes that drift between revisions
When drawings are revised, quantities change, and sometimes an item moves from one component to another. Keep the code stable where the item is the same, and add new codes for genuinely new items. Retired codes should be marked, not reused. Linking each line back to its source drawing helps here, and our note on linking each BoQ line to its drawing revision sets out a way to do it.
Coding without checking the measurement rule
A correct code attached to a description that does not meet the NRM2 rule still gives you a poor line. Check the description and unit against the rule for the work section, then code. Our overview of NRM2 take-off rules for audit-ready BoQs goes into the rules that most often catch people out.
How NRM2 coding differs from other UK measurement standards
NRM2 replaced the Standard Method of Measurement, 7th edition (SMM7) for building work, as Designing Buildings notes. If a contract still names SMM7, you measure to SMM7 and do not mix rule sets.
The difference that matters for coding is the link to cost planning. NRM2 belongs to a suite in which NRM1 provides the element structure for estimating and cost planning, and the NRM2 elemental BoQ reuses levels 2 to 4 of that structure. That is why an NRM2 BoQ can reconcile with an NRM1 cost plan more directly than a BoQ prepared under an older method. Other standards, such as those used for civil engineering, have their own rules and their own structures, so check which one the contract names before you start.
For trade-specific work, the same principles apply. Services measured to NRM2 still need a coded structure that matches the cost plan, and the MEP quantity take-off steps show how that looks in practice.
Applying the coding to a small project
For a house extension, the elements you are likely to code include substructure, frame or walls, roof, windows and doors, finishes and services. Work down the elements and, within each, list the components you can see on the drawings. Then add the subcomponents the measurement rules need you to separate.
A few habits make this faster and cleaner:
- Code from the drawings in a fixed order, such as substructure upwards, so you do not skip elements.
- Keep a running list of the components you have created so you do not duplicate them.
- Check section and elevation quantities against the plan before you finalise codes. Our section and elevation worked examples show how.
- Review the coded BoQ as a whole. Sort by code and scan for gaps, duplicates and lines that sit in the wrong element.
The house extension take-off checks apply the same approach to a full small project.
Where software fits
Codification is tedious to do by hand and easy to get slightly wrong, which is why most surveyors keep a template. QuantiFlow is a platform in development that reads construction drawings and produces a draft Bill of Quantities for a quantity surveyor to review and sign off. The coding decisions, the structure and the final judgement stay with you. You can see the plans and details on the QuantiFlow site.
FAQ
What is the difference between NRM1 and NRM2 codes?
NRM1 sets the element structure for estimating and cost planning. NRM2 uses the same group element, element and sub-element levels (levels 2 to 4) in an elemental BoQ, then adds user-defined component and subcomponent levels for detailed measurement.
Do I have to use the NRM2 coding structure on every BoQ?
NRM2 offers three principal breakdown structures: elemental, work section and works package. Which you use depends on the project and on what the client or contractor needs, so agree it before you start measuring and keep to it.
Who defines levels 5 and 6?
You do. In an elemental BoQ, NRM1 predefines levels 2 to 4, and the surveyor sets the component and subcomponent codes. They should be clear, distinct and applied consistently across the whole BoQ.
Does the code tell me the unit of measurement?
No. The code identifies where an item sits in the structure. The unit and the required description come from the NRM2 measurement rule for the relevant work section.
Sources
- RICS guidance note: New rules of measurement (NRM2, 2nd edition, 2021)
- NRM 2: Detailed measurement for building works, extract
- Standard Method of Measurement SMM7, Designing Buildings
Recommended
- NRM2 takeoff rules to make BoQs audit ready for UK quantity surveyors
- NRM2 explained: the RICS standard for measuring building works
- Require Contractor Breakdowns: NRM2 Preliminaries for UK QSs
- 6 Fields to Standardize BoQ Items for UK QSs with NRM2 and Uniclass
This article is for general information only and is not professional, legal or commercial advice. Quantity surveying decisions should be taken by a qualified professional with reference to the specific project, drawings and contract in question. Content is produced with AI assistance and reviewed before publication. QuantiFlow Ltd accepts no liability for reliance on it.