A big job — an extension, a loft conversion, a full rewire — usually means a payment structure with several instalments rather than one invoice at the end. Get that structure wrong and you’re exposed either way: pay too much too early and you’re relying entirely on trust if the builder disappears; withhold too much and you risk a good tradesperson walking off a job that isn’t paying its own way.
A fair stage payment structure ties every payment to work that’s actually been completed and inspected, keeps the deposit small relative to the total job value, and holds back a final retention until snagging is genuinely finished — not when the builder says it’s finished. Both sides benefit from a schedule that’s written down before work starts, rather than negotiated as each milestone arrives.
Why payment structure matters more on bigger jobs
A same-day repair is usually paid on completion, in full, with little room for dispute. A multi-week or multi-month project is different: materials need buying, labour needs paying weekly, and a builder covering all of that out of pocket until the end of a large job isn’t realistic for most small firms. Stage payments exist to keep cash flowing on both sides — the trick is making sure the amounts and the timing are fair to both.
What a reasonable deposit looks like
A deposit before work starts is normal and reasonable for a job involving bespoke materials, a skip, scaffolding or significant advance ordering — but it should be proportionate, not the bulk of the contract value paid upfront on trust alone. A request for the majority of the job value before any work has started is one of the clearer warning signs worth pausing on.
What the deposit should actually cover
Ask what the deposit is for specifically — materials, a skip hire deposit, scaffolding — rather than accepting a round number with no explanation. A builder who can itemise what the deposit covers is generally more reassuring than one who can’t.
Structuring the stage payments themselves
Tie payments to milestones, not dates
The strongest stage payment schedules are tied to defined, checkable milestones — foundations complete, walls up to roof height, first fix complete, plastering done — rather than simply to a calendar date. A date-based schedule means you’re paying regardless of progress; a milestone-based one means you’re paying for what’s actually there to inspect.
Agree the schedule before work starts
Put the full payment schedule in the contract or written quote before any work begins, with each stage’s amount and trigger spelled out. Verbally agreeing “we’ll sort it as we go” is exactly the kind of ambiguity that turns into a dispute halfway through a job.
Here’s the opinion worth having: a written stage payment schedule protects the builder just as much as it protects you, and a reputable tradesperson should want one as much as you do — treat reluctance to put it in writing as a signal, not a formality you can skip.
Inspect before you pay
Where practical, physically check that a stage is genuinely complete before releasing payment, rather than paying on the builder’s word alone. For structural stages in particular, this is also a natural point to involve a surveyor or building control inspector if one is due at that stage anyway.
Retentions: the final safety net
A retention is a small percentage of the total job value — commonly discussed in the trade as a modest slice of the contract — held back after the main work is finished and released once any snagging is resolved. It exists specifically to give the homeowner leverage to get small defects fixed, rather than chasing a builder who’s already been paid in full and moved on to the next job.
Don’t confuse retention with an excuse not to pay
A retention should be a small, pre-agreed amount for genuine snagging — not a way to hold back a large final payment indefinitely over minor cosmetic points, or because you’ve simply decided you’d rather not pay yet. Unreasonably withheld payment is one of the more common causes of disputes escalating, and it can undermine your position if the disagreement ends up needing formal resolution.
Protecting larger payments
For substantial jobs, some homeowners use a solicitor’s client account, an escrow-style payment service, or an insurance-backed guarantee scheme to hold stage payments until they’re released against agreed milestones, rather than paying the builder directly at each stage. It adds a layer of process, but on a job worth tens of thousands of pounds, that process is usually worth the modest extra friction.
What to do in the next 30 minutes
Ask any builder you’re getting quotes from for their standard payment schedule before you compare prices.
Check that any deposit requested is proportionate to the job and specifically explained.
Draft milestone triggers for each stage payment, rather than dates, and put them in writing.
Confirm the retention percentage and what triggers its release before signing anything.
Look into payment protection options if the job is a significant proportion of your savings.
Log your agreed payment schedule and each instalment against the job in Home+, so there’s a clear, dated record if a dispute over what’s been paid — and what’s owed — ever comes up.
Log your project’s stage payments in Home+ as you go, so you’ve always got a clear, dated record of what’s been paid and what’s still owed.
FAQ
How much deposit should I pay a builder for a big job? A proportionate amount relative to the total job value, tied to a specific, explained cost such as materials or scaffolding — not the majority of the contract paid upfront on trust.
What’s a fair retention percentage on a building project? A modest slice of the total contract value, held back specifically to cover snagging once the main work is complete, and released once agreed defects are fixed.
Can a builder refuse to work if I won’t pay a large deposit upfront? They can decline the job on those terms, but a request for the bulk of the contract value before work starts is a recognised warning sign worth treating with caution, not a standard you should feel obliged to meet.
What should I do if a builder wants payment before a stage is actually finished? Politely decline until the stage is genuinely complete and, ideally, inspected. A reasonable tradesperson will understand payment following completed, checkable work rather than a fixed date.
Is it reasonable to withhold the final payment until every last snag is fixed? A small, pre-agreed retention for genuine snagging is reasonable; withholding a large final payment indefinitely over minor issues, without having agreed that upfront, risks becoming a dispute in itself.
