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Measuring Variations for UK QSs: NRM2 From Instruction to Record

October 17, 2026
Measuring Variations for UK QSs: NRM2 From Instruction to Record

Measuring variations means quantifying contractually instructed changes for valuation and final account purposes. Start by confirming the written instruction and the clause authorising it, then establish whether the contractor's tender rates apply. Your controlling references are the RICS final account procedures and the measurement rules in NRM2.

TL;DR:

  • Only changes formally instructed under the contract can adjust the contract sum; verify the signer, date, authority clause, and affected drawings before valuation.
  • Check the Contract Particulars first: they may assign measurement to the Contract Administrator, contractor, or split duties by value; missed deadlines can delay certification.
  • Tender rates apply when work and conditions are similar, regardless of current market prices; otherwise, document a fair and reasonable assessment, derived rate, or contractual daywork.
  • When an instruction affects progress, assess directly resulting loss and expense alongside cost, while logging time effects, updating cash flow, and tracking contingency.
  • Tie each measured line to one drawing revision, retain signed daywork sheets and measurement calculations, and reconcile variations with provisional sums, setoffs, and interim payments.
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Table of Contents

What counts as a variation and where do you look in the contract?

A change is a variation only when it has been formally instructed under the contract. The RICS Final account procedures treat a variation as any change to the contract specifications or drawings that was formally instructed, and only those changes entitle the contractor to an adjustment of the contract sum. Contractors sometimes claim variations that nobody instructed, so at final account stage you need to separate the claimed from the instructed before any valuation begins.

Contract forms set out their own procedures for creating and recording instructions. Under JCT-style wording, the architect or contract administrator issues the instruction. The contract extracts we reviewed set out separate sections on variations, valuation, daywork and derived rates, and they expect measurement and valuation to follow the contract's own clauses.

When someone alerts you to a claimed change, run this checklist:

  • Locate the written instruction and check who signed it.
  • Record its date and reference.
  • Identify the clause that authorises it.
  • Check whether it amends the employer's requirements or only the contractor's proposals.
  • Confirm whether it changes the specification, the drawings, or both.

Who measures variations, and what must you check in the contract particulars?

Measurement responsibility is set in the contract, not assumed. In the contract clauses we reviewed, the Contract Particulars allocate measurement responsibility. They may require the Contract Administrator to measure all Orders or Orders above a stated value threshold, or name the Contractor to measure all Orders. A measured term contract sets out progress and final payments for both the case where the Contract Administrator measures and values and the case where the Contractor does.

Read the particulars before you pick up a scale rule, then act on what they say:

  • Invite the contractor to attend measurement and record that the invitation was made.
  • Keep signed measurement returns where the contract uses them.
  • Diarise the contractual timescales for certificates and applications for payment.

Misreading who is responsible has practical consequences. A valuation produced by the wrong party, or outside the stated timescale, can delay interim certification and leave the final account open longer than it needs to be.

Valuation principles: when do you use contract rates, derived rates or daywork?

The RICS Change control and management guidance sets the hierarchy. Value variations from the contractor's tender rates where the work is of similar nature and carried out under similar conditions. Where the original rates do not apply, assess the value on a fair and reasonable basis. Tender rates stay in play even when they differ from today's market rates, so a judgement about whether the work is still "similar" matters more than a rate check against current prices.

Work through the valuation in this order:

  1. Contract rates. Apply the tender rate where nature and conditions match.
  2. Other valuation basis. Where the tender rate does not apply, assess the value on a fair and reasonable basis and record the reasoning.
  3. Derived rates. Where no tender rate fits, check the contract's valuation provisions and document the basis used. NRM2 deals with derived rates.
  4. Daywork. Check the contract's provisions for daywork and follow them when valuing the work.
  5. Fair and reasonable assessment. Use this where no priced document gives a useful basis, and document the reasoning.

Document the evidence and assumptions supporting the valuation. For daywork, check the contract's requirements for records and supporting evidence.

Pro Tip: Try to agree the value before the work is done. The contract guidance expects the parties to endeavour to agree a price first, and a note of the chosen valuation approach on file saves argument later.

How do you measure a variation step by step under NRM2?

Follow the same sequence on every variation so that the record looks the same from one change to the next. This workflow draws on NRM2, the standard measurement framework for bills of quantities, and on the RICS guidance above.

  1. Confirm the instruction. Capture the written instruction, its revision and date, and the clause that authorises it.
  2. Map scope to the bill. Identify the affected bill of quantities items or create new NRM2 items. Decide whether the change is remeasured or sits against a provisional or prime cost sum.
  3. Measure the change. Apply NRM2 rules, measure to the drawings or model output, and tie each measurement to a single drawing revision. Where you are remeasuring after an issue of revised drawings, our guide to remeasuring after revisions gives a practical checklist.
  4. Select the valuation basis. Choose contract rate, derived rate or daywork. Prepare a transparent build-up and note any adjustment for conditions that differ from the tender assumptions.
  5. Assemble the evidence. Gather drawings, photographs, daywork sheets, subcontractor quotations, purchase orders and any programme revisions.
  6. Submit, negotiate and record. Log the agreed value, or the disputed status, in the change register, then update the cashflow forecast and the final account.

Pro Tip: Name each measurement line after the drawing revision it came from. If a later revision lands, you can see in seconds which lines it touches.

What belongs in the variation record and final account substantiation?

Every variation in the final account should be traceable back to a formal instruction. The RICS final account procedures and change control guidance treat documenting instructions and valuing changes as core parts of managing change. A complete record usually holds:

  • The formal instruction, with its clause reference.
  • Revised drawings and the bill of quantities line references they affect.
  • Quantified build-ups showing the NRM2 rules applied.
  • Daywork records, quotations and invoices.
  • A note of any adjustment for administrative cost of the change, which the RICS guidance says valuations should include.

In the final account itself, reconcile adjustments to provisional sums, show set-offs, and state how each variation has fed through interim payments. Cross-reference each measured line to one controlling document or drawing revision. Our note on NRM2 takeoff rules for audit-ready bills covers that traceability in more detail.

A valuation rule worth printing: under the RICS Change control and management guidance, tender rates apply where the work and conditions match, otherwise value on a fair and reasonable basis. That single rule decides most disputes about rate.

How do you manage the programme, cost and risk consequences?

A variation rarely changes cost alone. The RICS guidance asks you to log each change in the risk register and assess its combined time and cost effects, then draw on contingency set up in the early stages to pay for changes that were predicted or turn out to be unpredictable. Where the instruction affects progress, the contract guidance says the valuation should also include loss and expense directly arising from that effect.

In practice:

  • Record every variation in the change register on the day it is instructed.
  • Assess extension of time and loss and expense alongside the cost valuation, not afterwards.
  • Update the cashflow forecast once a value is agreed, and tell the client what has moved.
  • Draw on contingency for predictable changes and report the remaining balance.
  • Pursue a pre-agreed value first. If that fails, document the valuation method and the evidence behind it.

What do different variations look like when measured?

The examples below illustrate how to approach different types of variation.

Four variation types and their measurement approaches

An omission and substitution. An instruction deletes one floor finish and substitutes another. Measure the omission against the original bill item, then measure the substitute as a new item. Check the contract's valuation provisions to determine which rates apply.

An addition with no matching item. An extra partition appears on a revised drawing. Measure it to NRM2 and check the bill for a comparable partition. Where one exists in similar conditions, use its rate. Where none does, build a derived rate from labour, board, studwork and finishes.

Work that cannot be measured. Unforeseen making good around services is recorded as daywork. Value it from signed daywork sheets and the contract's daywork rates, and attach the sheets to the valuation.

A provisional sum adjustment. An instruction defines work previously held under a provisional sum. Omit the sum, then value the instructed work. The net figure is what moves the contract sum.

Where do AI tools like QuantiFlow fit into variation measurement?

AI tools sit at the measurement stage and nowhere else. Our own product, QuantiFlow, is in development: it reads construction drawings and produces a draft Bill of Quantities for a quantity surveyor to review and sign off. For variations, a surveyor can review the draft Bill of Quantities alongside the relevant drawings and decide what the instruction changes.

The judgement stays with you. Confirming the instruction, choosing the valuation basis, deciding whether tender conditions still apply, and negotiating the outcome are professional calls that no draft can make. Any draft measurement needs the same checks you would apply to your own: is each line tied to one drawing revision, does it follow NRM2, and does it reconcile to the bill?

If you use a tool like this, keep the audit trail intact. Record which drawing revision produced each draft line and who reviewed it. Our NRM2 explainer summarises the rules a reviewer will check against.

How should surveyors, contractors and architects collaborate on variation measurement?

Most variation disputes start with someone not knowing what has been instructed. The RICS Change control and management guidance asks professionals to understand the change control procedures and digital portals in each contract form and to be aware of every party's obligations under it. Good collaboration starts there.

  • Agree at the first meeting who issues instructions, who measures, and how revisions are numbered.
  • Ask the architect to issue every change as a formal instruction with a drawing revision.
  • Share measurement build-ups with the contractor before submitting, and invite comment.
  • Hold a short, regular change meeting so values are agreed while the work is fresh.
  • Where visual material helps substantiate a scope change, commission it early. A specialist such as Visual Trick produces architectural visuals that can support a revised design.
  • If addenda arrive during tender, our triage for tender addendum quantities shows how to keep the bill current.

FAQ

Is every change on site a variation?

No. Under the RICS final account procedures, only changes formally instructed under the contract adjust the contract sum. A change the contractor makes or claims without instruction needs verification before any valuation.

Who measures a variation?

The contract decides. The Contract Particulars can name the Contract Administrator, split responsibility by value, or name the Contractor, as in the contract clauses we reviewed. Check them before measuring.

Which rates do you use to value a variation?

Use the contractor's tender rates where the work is similar in nature and conditions, as the RICS guidance requires. Where they do not apply, value on a fair and reasonable basis and document your reasoning.

What measurement standard applies to variations?

NRM2 is the standard measurement framework for bills of quantities, so it is the appropriate basis for quantifying changes to a measured contract. Apply its rules to any new items you create.

Can a valuation include loss and expense?

Where the instruction affects progress, yes. The contract guidance says valuation can include loss and expense directly arising from that effect, so assess it alongside the cost.

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.