How Do You Handle Variations Mid-Project?

In writing, priced before the work starts, with a signed instruction and a programme impact stated. A variation agreed verbally is a variation that will be argued about at the final invoice, and the argument is always about the same thing: what was agreed.

The process needs to be three steps, not one: instruction, price, acceptance. Skipping the middle step is how a 300 pound change becomes a 1,200 pound invoice.

What counts as a variation?

Any change to the agreed scope, specification, sequence or programme. Including omissions, substitutions and client-supplied items that change the installation.

A change of mind is a variation. So is a discovery that requires work outside the drawings, even though nobody chose it.

How should a variation be priced?

Against the schedule of rates in the contract, plus the stated margin on materials. If there is no schedule, agree a price before the work, not after.

Pricing after the event always favours the person who did the work. That is not dishonesty, it is the natural asymmetry of information.

What if the price cannot be agreed in time?

Agree a ceiling and a mechanism: work proceeds to a stated maximum, priced at day rates, with the balance settled later. Written down, before the work.

An unbounded instruction is a blank cheque. Never give one, however urgent the reason.

Who should sign the instruction?

The person paying, every time. On a couple’s project, both names, or one nominated decision-maker in writing at the start.

Two decision-makers with different views is the fastest route to a disputed variation.

How should variations affect the programme?

Every variation has a time impact, even a small one. State it in days and add it to the completion date at the time, not retrospectively.

Accumulating time impacts and revealing them at the end is the standard route to a dispute about delay.

What is the difference between a variation and a provisional sum?

A variation changes the scope. A provisional sum is an allowance for scope that was always included but could not be priced precisely.

Spending a provisional sum is not a variation, but exceeding it is. Track both against the same log.

How many variations are normal?

Five to fifteen on a typical house renovation, and half of them are discovered conditions rather than changes of mind. A project with none is either very well specified or not being recorded.

The number matters less than the recording. Unrecorded variations appear at the end as a single large number.

Should variations be paid immediately?

No, they should be invoiced at the next stage payment, priced and signed. Immediate cash payment leaves no record and no leverage.

Where a variation is large, agree a staged payment for it rather than a lump sum in advance.

What if a variation is caused by the contractor’s error?

Then it is not a variation, it is a defect and it is corrected at their cost. The distinction is whether the work was required by the contract and done wrongly.

Put the position in writing immediately. A polite written note preserves the relationship and the record.

How do you handle an omission?

As a negative variation, priced at the contract rate, and deducted at the next payment. Contractors sometimes forget to price omissions in the client’s favour.

Ask for it explicitly. The saving is real and it should appear on the statement.

What about a substitution the contractor proposes?

Acceptable if it is equal or better, in writing, with the price difference stated. A substitution that saves the contractor money and costs you quality is not a variation, it is a downgrade.

Specify “or equivalent approved by the client” in the contract to make this explicit.

How should the log be kept?

A single table: number, date, description, cause, price, time impact, approval, status. Shared with the contractor weekly.

A shared log prevents the end-of-project surprise. The surprise is always larger than the sum of the entries.

What if the contractor starts work without an instruction?

You are entitled to challenge the invoice, and you should do so in writing on the day. Silent acceptance is treated as agreement.

Most disputes about variations begin with work that was done in good faith but never priced.

How does a variation affect the final account?

It is added or deducted at the contract rates, then the retention applies to the adjusted total. The final account should reconcile exactly to the log.

If it does not, the discrepancy is either an unrecorded variation or an arithmetic error. Both are worth an hour of checking.

Can a variation be refused?

Yes. The contractor can decline work outside the contract, and the client can decline a price. That is what the process is for.

A refusal is better than an unrecorded instruction. It keeps the contract intact.

What about a variation requested by the building inspector?

It is still a variation, priced the same way, but it is not optional. Record the inspector’s requirement and the date, and price it before proceeding.

Work required to achieve compliance is rarely negotiable, but it is always priceable.

How do you avoid variations altogether?

By specifying fully before tender, deciding services first, and not changing your mind during the build. Two of those three are within the client’s control.

The third, discovered conditions, is what the contingency is for. No amount of specification finds asbestos behind a tile.

What is the most common variation dispute?

Whether the work was already included. That question is answered by the specification, which is why a detailed specification is worth more than a detailed contract.

When the specification is silent, the argument is about memory. When it is explicit, the argument is about arithmetic.

Should a variation be added to the contract?

Yes, as a signed addendum or a formal instruction sheet attached to it. A variation recorded only in an email chain is harder to enforce and easier to forget.

Keep the numbering sequential. A variation without a number cannot be reconciled at the final account.

What is the most common variation on a kitchen?

A service position that cannot be achieved as drawn: a waste that will not fall, a flue that cannot exit, or a circuit that has no space in the board. Each is priced and programmed at the point of discovery.

These are the variations a good survey prevents. The guide on moving a kitchen sink covers how to test the waste route before demolition.

What should the final account include?

The contract sum, every variation with its instruction, every omission, the adjusted total, the payments made and the retention held. Signed by both parties.

That document closes the project. Without it, small items stay open for months. The guide on payment staging shows where variations sit in the schedule of payments.

Change control is unglamorous and it is the difference between a project that ends cleanly and one that ends in argument. The guides on payment staging and on contingency cover the money side.