Measuring an Interim Valuation: From Site Measure to Certified Sum

How a monthly construction valuation is actually built: what is measured, how materials on site are treated, and what has to be agreed before a certificate can be issued.

An interim valuation is not a progress opinion. It is a measurement of work properly executed, plus any amounts the contract allows for materials, minus deductions the contract permits. Doing it in that order, with a record at each step, is what stops the monthly payment conversation becoming a negotiation. The sequence below is the one a disciplined quantity surveyor follows every month.

Before stage one

Before the first valuation you need an agreed measurement basis, an agreed breakdown of the contract sum, a diary date for the joint site measure and a shared understanding of what counts as work properly executed. If those are settled in month one, the remaining valuations are arithmetic. If they are not, every month reopens the same arguments. Contractual periods and procedural requirements differ between forms and are revised periodically, so read your own clauses rather than relying on habit.

• Confirm the agreed breakdown of the contract sum, whether a priced bill, an activity schedule or a payment schedule.
• Fix the monthly valuation date and the joint measurement appointment for the whole programme.
• Agree what evidence will support materials on site and whether off site goods are valued at all.
• Confirm the retention percentage, the limit if there is one, and when it steps down.
• Identify who issues the certificate and what the contract says about the time for doing so.

Stage 1: Walk the works and measure what exists

Attend site with the contractor surveyor and measure physically completed work against the agreed breakdown. Measure what is there, not what the programme says should be there. Where an element is part built, decide how it is apportioned and record the basis, for example a column cast but not stripped, or blockwork built but not yet rendered. Partial items are where most valuation disputes begin, so write the apportionment down and have both parties initial it.

• Deliverable: A measured record of completed and partly completed work, signed on site by both surveyors.
• Owner: The quantity surveyors for each party, jointly.
• Approval gate: No item is carried into the valuation without a measured basis or an agreed apportionment.

Stage 2: Separate work properly executed from work merely present

Work that is defective, not in accordance with the specification, or awaiting a required test is present but not properly executed. Check the inspection and test records before valuing an element: a concrete pour with no cube results, a waterproofing layer never witnessed, a pipe run never pressure tested. Valuing unproven work transfers the risk to you, and recovering it later means deducting from a future valuation, which is always a harder conversation than declining it now.

• Deliverable: A list of items held out of the valuation with the reason and the evidence needed to release them.
• Owner: The supervising engineer, with the quantity surveyor.
• Approval gate: Every held item has a stated route to being valued next month.

Stage 3: Value materials and goods under the contract rules

Most forms allow unfixed materials on site to be valued if they are properly stored, protected, not delivered prematurely and intended for the works. Off site goods are usually valued only if the contract specifically allows it and only against conditions such as identification, insurance and a vesting arrangement. Check the clause, then check the physical position: material stacked in the open and deteriorating is not properly protected, and valuing it funds its own damage.

• Deliverable: A materials schedule with quantities, invoices, location, storage condition and ownership evidence.
• Owner: The contractor surveyor, verified by the supervising team.
• Approval gate: Each valued material has an invoice, a physical check and a protection confirmation.

Stage 4: Add variations in their proper state

Variations enter the valuation at the value agreed, or at a fair interim valuation where the final figure is not yet settled. Keep agreed variations, submitted but unagreed variations and instructed but unpriced work in three separate columns. Mixing them hides how much of the valuation rests on numbers nobody has accepted, and that is precisely the figure you need to watch, because it is the forecast of your next dispute.

• Deliverable: A variation register with status, instructed value, agreed value and the amount included this month.
• Owner: The quantity surveyor.
• Approval gate: The register reconciles to the valuation and to the cost report.

Stage 5: Apply the contractual adjustments

Deduct retention at the stated percentage, recover the proportion of any advance payment due under the repayment schedule, add or deduct any fluctuation adjustment the contract provides, and apply anything the contract expressly permits you to set off. Each adjustment needs a clause reference. An adjustment without a clause behind it is a deduction the contractor can challenge, and it undermines the credibility of everything else in the certificate.

• Deliverable: An adjustment schedule with the clause reference and arithmetic for each line.
• Owner: The quantity surveyor.
• Approval gate: Every adjustment line cites the clause that authorises it.

Stage 6: Reconcile against the previous certificate

Build the valuation cumulatively, then show the movement: cumulative gross value, less previously certified, equals the amount now due. Reconciling monthly catches arithmetic errors, double counting of variations and items quietly valued twice under different headings. It also produces the audit trail that makes the final account straightforward, because the final account is nothing more than the last of these reconciliations with everything settled.

• Deliverable: A cumulative valuation statement showing this month movement and the running total.
• Owner: The quantity surveyor.
• Approval gate: The cumulative figures tie back to every previous certificate without a balancing adjustment.

Stage 7: Certify within the contractual period and state the reasons

Issue the certificate inside the period the contract allows, and where the certified sum differs from the application, state what was reduced and why. A certificate that silently cuts an application invites a formal dispute, while one that itemises the reductions turns the disagreement into a technical list that can be closed over the following month. Late certification is a common and avoidable breach, and it damages your position on everything else.

• Deliverable: A payment certificate with a reduction schedule attached.
• Owner: The person named in the contract as certifier.
• Approval gate: The certificate is issued on time and the reasons for every reduction are written down.

Stage 8: Close the month with a payment and a record

Ensure payment follows certification within the contractual period, and file the complete month pack together: the measured record, the materials schedule, the variation register, the adjustment schedule, the certificate and the reduction notes. This pack is the evidence base for the final account and for any claim. Filing it properly takes under an hour a month and saves weeks at the end of the job.

• Deliverable: A dated monthly commercial pack in a single location, accessible to both parties.
• Owner: The commercial manager.
• Approval gate: The pack is complete before the next valuation date.

Handovers between stages

The weak handover is between the site team and the commercial team. If the engineer holds items for quality reasons but never tells the surveyor, the items get valued; if the surveyor holds items but never tells the engineer, nobody chases the evidence that would release them. Fix it with a single held items list reviewed in the same meeting each month by both. The second handover is to accounts, where a certificate that does not match the invoice format causes a payment delay that looks like bad faith and is actually administration.

How you know it is finished

The valuation cycle is working when the contractor application and your certificate differ by a small, explainable amount each month, and when the difference is made up of items both parties already know about. A pattern of large reductions means the application is being inflated or your measurement basis is not agreed, and in either case the problem is upstream of the valuation itself. Keep the monthly packs; they are the only contemporaneous record of what was built and when.

Domira builds and supervises projects across Saudi Arabia, and the commercial discipline above is how its projects stay inside their budget and their programme. Send the drawings, the contract or the site and Domira will tell you where the risk actually sits.