On every job, something changes: client wants extra sockets, architect redraws, steels come in late, ground is worse than anyone thought. That's normal. The problem isn't change -- it's doing it without a paper trail or a price.
This section is about turning "Can you just...?" into paid, recorded variations instead of charity work. The Construction Act is sitting behind this because every change should feed into a proper payment notice and cash-flow, not get buried until the end.
1. What a variation actually is
Different contracts use different words -- "variation", "change", "compensation event", "instruction" -- but they all mean the same thing: the work has moved away from what was originally priced.
A variation can be:
- Extra work (add a room, more sockets, thicker insulation).
- Omitted work (client drops the patio, changes finishes down).
- Changed work (different design, different spec, different method).
- Changed conditions that trigger contract rights (unforeseen ground, new regs, access issues -- usually under specific clauses).
Every one of those has a cost and a time effect. If you treat them as favours, you're burning your own margin.
2. Why changes wreck margins if you don't control them
Most contractors don't go bust because they can't build. They get crushed by "little" changes that were never priced or recorded properly.
When you don't run variations properly, this is what happens:
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You lose entitlement: lots of contracts say "no extra money/time unless you notify in X days" -- miss it and you hand the other side a technical defence to your claim.
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You lose evidence: no dated instruction, no sketch, no photos, no diary = "we never asked for that" at final account.
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You lose cash-flow: changes get parked "to sort at the end", so you're funding them for months instead of getting paid in the next valuation.
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You lose control of programme: you say yes to changes without getting time, so on paper you're late and open to delay damages even though you did more work.
The Construction Act doesn't magically pay for variations, but it does give you a structure to bill for them and fight over them quickly if you need to.
3. The basic rules to protect yourself
Whatever contract you're on -- JCT, NEC, domestic -- the fundamentals are the same.
You want to:
Follow the contract's change procedure
- Most standard forms set out who can instruct changes, how they have to do it, and when/how you must notify and price them.
- Get into the habit of asking: "Is that a formal instruction?" and "Can you confirm that in writing?" before you crack on.
Price and time every change
- Don't just say yes. Put a number and a time impact on it, even if it's provisional.
- In NEC, that's a quotation for a compensation event; in JCT, it's valuation of a variation and, where relevant, an EOT and loss/expense; in domestic, it's a simple written extra with a cost and a few words on timing.
Keep a variation account running
- Keep a live log: date of change, instruction ref, description, cost, time impact, status (priced, agreed, disputed).
- This becomes your variation schedule in monthly valuations and at final account.
Feed variations into your payment applications
- The Act needs an "adequate mechanism" and payment notices; variations are part of the value you claim each cycle.
- If you don't put them in your applications, don't be surprised when they're not paid.
You're not being awkward -- you're just matching extra work with extra money and time, which is exactly what construction contracts are built for.
4. How this looks in the main contract types
You don't need to memorise clause numbers, but you do need to know the flavour.
Under JCT
- Architect/CA or Employer's Agent issues instructions that change the works -- those are your variations.
- You're entitled to have them valued (rates, similar work, or fair valuation) and, if they delay you, to claim extensions of time and possibly loss and expense under the relevant clauses.
- Many amended JCTs add stricter notice requirements -- ignore those at your peril.
Under NEC (as compensation events)
- Changes come through instructions, changed conditions or other listed compensation events.
- You must notify within the time stated and then submit a quotation (cost and time) based on your programme and Defined Cost.
- If you don't notify in time, you can lose the right to extra money/time for that event.
On domestic jobs / simple contracts
- Stick to a simple rule in your terms: no change without something in writing that says what's changing, what it costs, and whether it affects time.
- That might just be a signed change form or a clear email chain -- but you need something.
Different forms, same idea: change = documented instruction + price + time, not a vague chat in the driveway.
5. A simple process you can use on any job
You don't need a QS degree to manage variations; you just need a routine you stick to.
On every project:
When someone asks for a change:
- Write it down immediately (email, form, app) with date, who asked, and what they want.
- Reply with: "To confirm, this is a variation. Estimated cost £X and +Y days. Please confirm to proceed."
When you get an instruction:
- Give it a reference number and log it in your variation account.
- Attach any sketches, updated drawings or emails to that entry.
In each valuation or invoice:
- Include a variations section listing each change, reference, and value claimed to date.
- Make sure your application dates and payment notices under the Act cover that value, so you can argue for it in adjudication if needed.
Near the end:
- Reconcile your variation account with the other side early. Don't leave 50 unresolved changes for the last meeting when everyone's tired and skint.
That's how you turn "scope creep" from a slow bleed into something you're paid for, at the right time, on the right paperwork.
Disclaimer: SiteKiln gives you plain-English information, not legal advice. Talk to a solicitor before making big decisions on live disputes.
What to do next
- Set up a simple variation log today: date, instruction ref, description, cost, time impact, status. Use it on every job.
- Next time someone asks for a change, reply with: "To confirm, this is a variation. Estimated cost is X and it adds Y days. Please confirm to proceed."
- Include a variations section in every payment application, listing each change with its reference and value claimed.
- Read the change/variation clause in your current contract and find out who can instruct changes and what the notice deadlines are.
- Near the end of a job, reconcile your variation account with the other side early -- do not leave it all for the last meeting.
Sources
- Housing Grants, Construction and Regeneration Act 1996 -- https://www.legislation.gov.uk/ukpga/1996/53/contents
- Scheme for Construction Contracts (England and Wales) Regulations 1998 -- https://www.legislation.gov.uk/uksi/1998/649/contents
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