Why VOs Are Not Agreed: Five Common Submission Errors

A variation submission can contain a reasonable amount but still be difficult to assess. The assessor needs to understand why the work changed, what changed, how the quantity was measured and why the proposed rate follows the contract.

The HKIS practice note on valuation of variations sets out a structured valuation approach. Contract rates should be considered first where applicable, followed by a rate formed on a pro-rata basis where appropriate, then a fair or “star” rate. Daywork is not a general fallback; it depends on the conditions required by the contract. This sequence is more defensible than selecting whichever method produces the highest value.

Error 1: the instruction and notice trail is incomplete

An email, marked-up drawing or verbal direction may explain what happened operationally, but the contract may require a particular person, form or notice period. Record:

• who gave the direction;
• when it was received;
• the drawing, RFI, SI or meeting record concerned;
• what action was taken; and
• when the commercial effect was notified.

If a verbal instruction must be acted on urgently, confirm it in writing promptly and request formalisation in accordance with the contract.

Error 2: the changed scope is not isolated

“Additional work” is not a measurable description. A useful scope statement identifies:

• the original requirement;
• the revised requirement;
• location and drawing references;
• additions, omissions and abortive work; and
• the reason the change was necessary.

Before-and-after drawings or a marked-up comparison often explain the change more effectively than a long narrative.

Error 3: the measurement cannot be reproduced

The assessor should be able to trace each quantity to a drawing, site dimension or record. A measurement sheet should state the location, dimensions, units and calculation. Where the contract adopts a standard method of measurement, the item description and coverage should follow that basis.

Check whether associated work is already included in the item coverage or preliminaries before adding it separately. This avoids both omission and double counting.

Error 4: the rate basis does not follow the contract

A supplier quotation alone does not establish the correct variation value. The submission should explain the valuation route:

1. Is there an applicable contract rate?
2. Can a similar rate be adjusted on a pro-rata basis?
3. Is a new star rate required?
4. If daywork is proposed, were the contractual prerequisites and records satisfied?

A star-rate build-up should show labour, material, plant, waste, delivery and applicable additions separately. Supporting quotations should be relevant in date, scope, quantity and commercial terms.

Error 5: records were created after the work

Late reconstruction is vulnerable because labour, access constraints and abortive work may no longer be visible. Keep contemporaneous:

• dated photographs linked to location;
• daily records and labour allocation;
• delivery notes and material invoices;
• plant records;
• inspection or testing records; and
• correspondence showing the sequence of events.

The record should prove the work, not merely show that activity occurred somewhere on the project.

Fictional example

An MEP subcontractor is directed to reroute pipework above a completed ceiling zone. A stronger VO file would include the revised coordinated drawing, written confirmation of the instruction, marked-up original and revised routes, measured pipe and fittings, labour records for opening and reinstatement, dated photographs and a rate analysis linked to contract rates where applicable.

Submitting only a supplier invoice and a lump-sum labour allowance leaves the assessor unable to verify the changed scope or the valuation method.

Submission checklist

• Instruction and notice references are identified.
• Original and revised scope are compared.
• Quantities can be independently reproduced.
• The proposed rate follows the contractual valuation sequence.
• Omissions and abortive work are shown separately.
• Photographs and records identify date and location.
• The VO register matches the amount and status in the submission.
• Assumptions and exclusions are stated.

When professional support may help

QS support may be useful when a batch of VO has inconsistent formats, when the rate basis is disputed, or when the final account contains many completed changes with incomplete records. The priority is to build a traceable submission and identify evidence gaps before negotiation.