Industries

The variation: writing the change on the day it happens

Almost every site dispute begins with a sentence said in a doorway that nobody wrote down.

Published on 8 July 2026 — Algeria Agency

The article beside this one explains where the dispute comes from: from what was not in the quote. The diagnosis is exact and it stops where the work begins — how to stop it happening.

The answer is not an attitude or better communication. It is a procedure: a sheet, four lines, two signatures, the same day. It takes six minutes and it is almost always skipped.

It is skipped for a reason worth saying plainly: the moment a change is decided is the worst possible moment to produce a piece of paper. The client is pleased, the worker is waiting, the solution is obvious, and nobody wants to slow down.

This article describes what to write, when, who may ask, who may accept, and what happens to the schedule — which almost nobody writes down. It gives no overrun percentage, and section 10 says why.

The dispute begins with a sentence said on site

No site dispute begins with a disagreement. It begins with an agreement: a sentence said standing up, in a doorway, that everybody is happy about.

"While you are at it, you could move the socket." "Since you are here, do the same in the hall." "That tile is not right, we will pick another one." Every one of those sentences is a change to the contract, said as a detail, understood as a favour.

Three weeks later, two people remember the same sentence differently, and neither is lying. One heard "that is included", the other said "we will see at the end"; both are right about their own memory.

That is what produces the disputed invoice, not dishonesty. The mechanism is one of memory and it is thoroughly documented by any tradesman you ask: the disagreement is almost always about things decided verbally and never about things written down.

The consequence is that the procedure described here is not a defence against clients. It is a defence of memory, and it protects both parties exactly equally — which is the only reason a client accepts it.

What a variation is, and what it is not

A variation is a written addition to something that already exists. It does not replace the quote, does not rewrite it, and is not discussed in the same terms: it says what changes relative to what was agreed.

That dependency is what makes it short. A four-line variation is complete because everything it does not say remains true — the conditions, schedule and payment terms of the main document continue to apply.

It is not a new quote, and confusing the two is expensive both ways. Redoing a full quote for a moved socket is disproportionate and will not happen; treating a significant extension as a four-line variation leaves everybody without a frame.

The dividing rule is practical rather than legal: if the change alters the nature or scale of the work enough that the whole schedule moves, it is a quote. If it is an addition, a substitution or a deletion within work whose shape stays the same, it is a variation.

We give no template document and will not. The contractual content of a works contract depends on its nature and on the applicable regulation, and what follows is a description of method — the legal form is asked of somebody whose profession it is.

The five causes of change, and the one that is yours

A change on site comes from five places and it is worth knowing which, because the conversation about price depends entirely on it.

The client changes their mind: the most frequent cause and the simplest to handle, because nobody disputes it. The client discovers something as the work advances, and that is normal — the neighbouring article says precisely that they cannot picture it.

Something is discovered on opening up: a pipe where there was none, a substrate that will not hold, damp. Nobody is at fault, and it is the cause that produces the largest price movements.

A material is no longer available or its price has moved. An external constraint appears — a neighbour, a co-ownership, a permission. And finally the fifth: an error in the original quote that omitted something necessary.

That last one is yours and must be treated as such. An omission in the quote is not a variation to invoice: it is a correction, it is said out loud, and saying it costs less than slipping it into a line. Clients tell the two apart perfectly, and they remember for a long time.

The moment: the same day, on site

The variation is written on the day the change is decided, on site, before the corresponding work begins. That is not a demand for rigour: it is the only configuration in which both parties have the same thing in mind.

Written in the evening it is already a reconstruction. Written at the end of the job it is no longer an agreement but a claim — and it arrives at the moment the client is counting, which is the worst point in the whole project to present something new.

The real difficulty is social, not administrative. Producing paper at the moment somebody asks you a favour looks like distrust, and that is why the procedure is abandoned on most sites.

The wording that works presents it as what it is: "I will note it down so we both agree — it saves you a surprise at the end." Put that way, the request is accepted almost every time, because it visibly protects the client.

The medium does not matter. A duplicate book, a photograph of a handwritten sheet sent the same evening, a message repeating the four lines: what counts is the date, the content and the agreement — not the presentation.

The four lines of a variation

Four lines are enough and a fifth weakens them. What changes, what it costs, what it adds to the schedule, and the date with both parties’ agreement.

The first line describes the change in verifiable terms: not "kitchen modification" but "socket moved from the north wall to the east wall, plus two metres of chasing". A vague description produces exactly the dispute the document exists to prevent.

The second is the price, and it has to be given. "We will see at the end" is the most expensive sentence in this trade: it turns every change into a debt whose amount will be announced at the moment the client has no way left to refuse.

The third is the schedule, and it is the line nobody writes. A change that adds half a day really does add it, and a site that has taken six variations without ever mentioning time has a delay the client will attribute entirely to the contractor.

The fourth is the date and the agreement. A signature is best, an agreement written in a message is nearly as good, and a verbal agreement recorded in front of a third party beats nothing — but nothing is worth zero and it is the commonest case.

The price of a change depends on where the job has got to

A client struggles to accept that the same change costs three different prices depending on when, and they are right to find it odd until somebody explains it.

Before the corresponding work starts, a change costs the difference: the material that will not be bought against the one that will, and perhaps a little labour. It is the cheapest case by far.

During, it costs the difference plus the work already done. A chase filled and then cut again elsewhere is labour twice, and explaining that once avoids an argument at invoicing.

Afterwards, it costs removal. Laid tile that has to come up is a cost with no relation at all to the price of the tile, and it is the situation where the client is most surprised, because they compare with what they would have paid at the start.

That scale is told to the client at the start of the job, once, in three sentences. It looks like nothing and it completely changes how change requests arrive: people decide faster, and they decide before rather than after.

Who may ask, and who may accept

On a site several people talk: the owner, their spouse, a relative, sometimes an architect, sometimes a neighbour. All of them give instructions and they do not all agree with each other.

So one person has to be designated at the start as the only one who may request a change. It is not a formality: without it the contractor executes the last instruction received, and ends up answering to somebody who was not there that day.

On your side, one person may accept and sign. A worker who says "yes, no problem" to a request commits the business in the client’s mind, and he has neither the price nor the schedule in his head to do so.

What the team needs to be able to say is one sentence and only one: "I will note that; the boss comes by this afternoon and will confirm." It refuses nothing, promises nothing, and preserves the ability to price.

Both names are said at the first meeting and written on the quote. It looks excessive for a bathroom and stops looking excessive the first time a mother-in-law has a wall moved.

The free change: grant it, and say so

Some changes should cost nothing, and that matters commercially as much as honestly. A few minutes of adjustment, a preference on a detail with no consequence, a correction of one of your own errors.

The mistake is granting it without saying so. An unnamed free gesture does not exist: the client believes it was in the price, and you have given something away without their knowing.

So the right practice is to write the variation anyway, with a price of zero and a note that it is free of charge. It takes the same time, it documents the change — which is the document’s purpose — and it makes visible what you are doing.

The second effect is even more useful: a client who sees three variations at zero and one chargeable understands that the chargeable one is chargeable for a reason. Without the first three, the fourth looks like opportunistic billing.

The line has to be clear in your head before it is on site: free means costing neither material nor significant extra hours. Past that, giving becomes a habit the client folds into the price, and that is the start of a job that earns nothing.

The schedule moves too, and nobody writes it down

The schedule line is the most often omitted of the four, and it produces the most resentment. A job that was to take three weeks takes five, and the client does not connect it with the six changes they themselves requested.

They do not connect it because they have no reason to. Nobody told them, each time, "that adds a day"; they heard "yes, we can do that" six times and "we are running late" once.

Writing it on every variation turns resentment into arithmetic. At the end the client can read the six lines themselves and see where the two weeks came from, and that reading completely changes how they will speak about you.

The stated duration has to be frank, including when it looks disproportionate. A change requiring a trade to come back often adds several days of waiting for an hour of work, and that reality is better said at the moment of decision than at the moment of observation.

Finally, the cumulative effect deserves announcing once it becomes significant. At the third or fourth variation one sentence is enough: "with this one we are a week beyond the original quote". The client then decides knowingly, which is all anybody is owed.

Handover, snags, and the variation never signed

The end of a job is when everything that was not written down comes back at once. It is also when the balance is asked for, which puts both subjects in the same conversation.

The separation to hold is simple: a snag — work that is non-compliant or unfinished — is not the same thing as a disputed variation. Handling them together turns two settleable discussions into one general deadlock.

Snags are listed in writing, by both parties, walking the premises. A written list is bounded: when it is cleared, it is cleared. A verbal list grows at every visit, and there is no moment at which anybody can say it is finished.

The unsigned variation is the hard case, and it has to be treated as what it is: work genuinely done, genuinely requested, with weak proof. A dated photograph, a message, a witness are worth something; a total absence of trace is worth nothing, and then the skill is to settle rather than to dig in.

The rule of conduct that protects most is the least pleasant: a job finished with no written variations is a job whose extras are a negotiation rather than an invoice. Knowing that in advance leads to writing them down, which is this whole article’s purpose.

What is counted, and the figure that only exists where the problem does not

Three things are counted per job, and they fit on the same sheet as the variations. Variations written, changes carried out without one, and total days added.

The second is the only one that really counts, and it is filled in honestly at the end of a job: how many times did we do something that was not in the quote without writing it down. It is unpleasant and it falls on its own the moment it is counted.

The third explains a contractor’s reputation better than any other figure. A delay made entirely of days added by the client’s own requests is one thing; the same delay with no explanation is another, and from outside they are identical.

The figure we will not give is the average overrun on this kind of work, and the reason is a selection bias whose direction is particularly cruel.

Such a percentage can only be computed on jobs where the changes were documented — that is, on contractors already doing what this article recommends. The population measured is exactly the one that does not have the problem, and the resulting average systematically understates the case of the reader who does. A figure biased toward zero for whoever needs it most is worse than no figure at all.

What we do, and what we refuse to do

What we do is modest and material: we put the four lines into the format of a duplicate book you carry on site, we write the three sentences about the price scale to be said at the first meeting, and we prepare the sentence the team needs to know.

We do not draft your contractual documents and we give no legal opinion. The form of a works contract, what a variation must contain to be enforceable and what the regulation requires are matters for somebody whose profession that is; what we describe here is a working method.

We do not price your variations and we will not act as an intermediary in a dispute. We have not seen the site, we do not know your costs, and an estimate from us would become an argument in a discussion whose risk we do not carry.

We will promise no quantified reduction in disputes, for the reason written in the previous section: the starting figure is measured on a population that is not yours, and an improvement built on it would be a fabrication.

And the whole benefit is available without us. A book, four lines, the same day, and one sentence learned by the team: six minutes per change, and it removes almost all of what the neighbouring article describes as the mechanism of the dispute.

Frequently asked questions

Does producing paper mid-job not look like distrust?

That is the real difficulty, and it is social rather than administrative. The wording that works presents it as what it is: "I will note it down so we both agree — it saves you a surprise at the end." Put that way, the request is accepted almost every time, because it visibly protects the client.

What should a variation contain?

Four lines: what changes in verifiable terms — not "kitchen modification" but the precise move — what it costs, what it adds to the schedule, and the date with both parties’ agreement. The third is the one nobody writes, and it is the one that produces the most resentment at the end.

Can we say "we will see at the end"?

It is the most expensive sentence in this trade. It turns every change into a debt whose amount will be announced at the moment the client has no way left to refuse — which is the moment they are counting. Give the price there and then, even approximately and announced as such.

What if a worker has already said yes to a request?

Treat it as a commitment made, because that is what the client understood, and fix the cause. One person on your side accepts and signs; the team learns one sentence and only one: "I will note that; the boss comes by this afternoon and will confirm." It refuses nothing, promises nothing, and preserves the ability to price.

Should a free change be written up as a variation?

Yes, with a price of zero and a note that it is free of charge. An unnamed free gesture does not exist: the client believes it was in the price. And the side effect is the most useful — three variations at zero and one chargeable make clear that the chargeable one is chargeable for a reason.

By how much does a job typically overrun its quote?

We do not give that figure, and the reason is a selection bias. Such a percentage can only be computed on jobs where changes were documented — so on contractors already doing what this article recommends. The population measured is exactly the one without the problem, and the average systematically understates the case of the reader who has it.

Where we come in

A duplicate book taken to site, and four lines written at the first “while you’re here”, are worth more than anything anybody could invoice you on this subject.

We print those four lines onto a book that fits a jacket pocket.
We write the price scale you will say at the first meeting.
We leave you to fill it in, because it is only worth anything signed the same day.

Contract drafting and legal advice belong to your adviser: we will not touch either, and the form of a variation is their business.

See the Home & Construction page Start with the free audit

Let us talk about your project

A free audit, no commitment: we look at your online presence and tell you what is holding it back.

Request the free audit Write to us