How do you price extra work so the client actually pays?

The architect wants the doorway moved. It is a day of work, maybe two. You do it, because the job has to move. Three months later it is one line in a long email about what was “included”.

Pricing extra work has two halves, and builders usually lose on the first one, not the second.

Half one: get the instruction before the work

A variation starts life as an instruction from whoever your contract empowers to give one. The standard forms require instructions to be in writing, or confirmed in writing, and even where your contract is silent, a one-line email is the difference between a variation and a favour. See he told me to do it on site and who is actually allowed to instruct.

Half two: the valuation ladder

Your contract sets the rules, and the standard forms share one shape, a ladder you walk down only as far as you need:

• Contract rates, where the varied work is of similar character and done under similar conditions to something already priced. The strongest rung, because nobody can argue with their own rates.
• Adjusted rates, where the work is similar but the conditions or quantities are not: the contract rate, with a documented adjustment for what changed.
• A fair valuation, where nothing in the bill resembles the work. Now your records carry the whole figure.
• Dayworks, where the work cannot sensibly be measured at all: recorded hours, plant and materials plus the contract percentages. Powerful and abused, which is why it has its own page.

Start at the top. A price built from contract rates gets paid; a price built from a number that felt right gets discussed.

Agree the price before you build it, where you can

Many contracts allow a quotation for a variation before the work is done: your price, their acceptance, then the work. Where the mechanism exists, use it for anything big, because it converts a future argument into a present decision. Where it does not, send the build-up with the confirmation of instruction anyway. Practice, not law, and it works.

Why the smallest ones never get paid

The pattern is always the same: too small to stop and paper, too many to remember. Ten forgotten half-days is a week of unpaid work. The fix is boring: one register, every instruction on it the day it happens, with a price or a placeholder. The register is what turns “we did lots of extras” into a column of figures somebody has to answer.

What to do this week

1. Write down every un-papered change on the current job now, with dates, while the memory is fresh.

2. Send confirmations for the ones still warm: instruction, date, expected cost effect.

3. Price from the ladder, top down, and show the rung you used on the face of the build-up.

4. Carry variations into every valuation as they are done, not as a heap at the end. Interim payments are cumulative, and a variation certified this month is money this month.