How much should a builder charge for variations and extras?

Variations are where a lot of builders quietly lose money. Not through one big mistake, but through a hundred small extras that were underpriced, done as favours, or never charged for at all. "While you're here, can you just…" is one of the most expensive sentences in construction — because the honest, obliging builder absorbs it, and the margin disappears a favour at a time.

The fix is a simple, consistent way to price extras, and a professional way to present them.

Price the whole cost, not just the materials

The most common underpricing mistake is charging for the extra tap or the extra socket but not for the time, disruption and knock-on work it creates. A "quick" change on site rarely is. Price a variation as: the materials, the labour to fit it, any consequential work it triggers, and a fair margin — the same margin you would apply to the original job. An extra is not a charity; it is work, and it should carry your normal markup.

Do not do extras for free to "keep them sweet"

Builders often waive small extras hoping to bank goodwill. It rarely works the way you hope. Free extras teach the client that changes cost nothing, which invites more of them, and they set an expectation that becomes awkward to reverse when a bigger one comes along. Charging fairly and consistently is not mean — it is what a professional does, and clients respect it more than they resent it.

Always include the time impact

Cost is only half of a variation. A change that adds two days to the programme needs to say so at the point of agreement, not at the end. The omission of a timeline impact is one of the most common sources of dispute, because clients assume extras are cost-only and feel misled when a job overruns. State "+£X, +Y days" every time.

Present the price before the work, not after

This is the single biggest lever, and it is about psychology as much as numbers. The same £300 extra that causes a row when it appears on the final invoice is accepted without a murmur when the client agrees it in advance. Show the cost, get them to approve it, then do the work. A client who chose the upgrade knowing the price owns the decision; a client who discovers it later feels ambushed. The money did not change — the framing did. (The legal side of getting this right is covered in the anatomy of a variation.)

Keep a running total the client can see

Individual variations rarely cause "final account shock" — the cumulative effect does. Fifteen small extras totalling several thousand pounds the client never tracked will feel like an ambush at the end, even when each was agreed. A visible running total — original quote plus variations to date — removes the shock entirely, because the number was never hidden.

Builders Ready is built around exactly this: you propose a variation with a title, cost and time impact, the client signs it off on their phone before the work, and it flows into a live finance summary both of you can see. But the principle stands whatever you use — price the whole cost, include the time, get it agreed up front, and never let the total be a surprise.