Variations: how to price extras, get them approved and actually get paid for them
Every job changes. The client sees the space and wants the wall moved. The ground is worse than anyone thought. The architect revises the detail. Builders who handle these changes as priced, approved variations make money on them. Builders who "sort it at the end" give them away, and then argue about them.
The rule
No variation is done until it is priced and approved in writing. That is the only rule, and it has to be in the contract and in your habits. A text message from the client saying "yes, go ahead at £1,850" is written approval. A nod on site is not.
Pricing a variation
Price it the same way as the original quote: labour by the hour or day at the contract rate, materials at cost plus the agreed percentage, plant and skips, and the prelims effect if it extends the programme. Add the knock-on effects, which are what builders forget: the extra socket needs chasing and making good; moving the wall changes the floor finish quantities; the bigger window needs a new lintel and a structural check. State what the variation does to the completion date.
Where the contract has a schedule of rates, use it; it removes the negotiation. Where it does not, show the build-up so the client can see it is not a number plucked from the air.
Omissions
Variations go both ways. If the client decides to supply the kitchen themselves or drop the garden wall, the omission is valued at the contract rates less a reasonable allowance for loss of profit and any costs already incurred. Price omissions as carefully as additions; an omission of the fitted wardrobes at the quoted price is a loss if the materials are already ordered.
Unforeseen conditions
Rotten joists, a culvert under the foundation line, asbestos in the artex: these are variations if the contract says they are, and a cost to you if it does not. The quote should have provisional sums or a clause making unforeseen conditions a variation at agreed rates. Then when the digger finds the well, you stop, photograph it, price the extra and get it approved, all the same day.
Getting it approved quickly
Speed is the whole game. A variation that takes a week to price stalls the job and annoys everyone. Price it on site, send it from your phone, and make approval a tap. EstiMate's variations do exactly this: the extra is priced from the job's rates, the client gets a notification, approves it in their portal, and the contract sum and the programme update automatically. The approval is logged with a time stamp.
Invoice as you go
Approved variations should be invoiced at the next stage, not rolled into a final account that becomes a negotiation. On a stage-payment job, add the variation to the next invoice with a reference to the approval. On a measured contract, include it in the next application with the instruction attached. Once a dozen variations are sitting in a final account, every one of them is open to challenge.
Commercial contracts
On JCT and NEC contracts the variation procedure is formal: an instruction from the contract administrator or project manager, a quotation within a set period, and an agreement or a valuation. Follow the timescales; a missed notice under NEC can lose the entitlement entirely. Keep the instruction, your quotation and the agreement together on the job, and update the programme every time.
The record that protects you
The site diary should note the day the change was requested, by whom, and the day it was approved. When a client disputes an extra months later, the diary entry, the priced variation and the time-stamped approval end the discussion. That is why the variation process is not admin; it is the difference between a profitable job and a disputed one.
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