Almost no domestic project runs to the original scope without a single change — a socket moved, a window swapped, a decision made once a wall is opened up and something unexpected is found behind it. Change control is simply the discipline of handling those changes formally instead of letting them accumulate informally.
Where this discipline is missing, the final account often comes as a shock, not because the work was overpriced, but because nobody agreed the individual changes as they happened.
Raising the change in writing
The first step in any properly controlled change is putting it in writing — an email, a message, a note on a site diary — rather than a verbal agreement on site that both parties remember slightly differently a month later. This doesn't need to be formal, just recorded.
Whoever spots the need for a change, whether it's the client wanting something different or the builder finding an unforeseen issue behind a wall, should raise it as soon as it's identified rather than letting several changes accumulate before mentioning any of them.
Pricing the impact before proceeding
Once a change is raised, it should be priced — both the cost impact and any effect on the programme — before work on it proceeds. This might be a same-day estimate for a small change, or a short pause for a bigger one while the impact is properly worked out.
Proceeding with a change before its cost is known removes the client's ability to decide whether it's worth doing at that price, which is precisely the decision the process exists to protect.
Getting written acceptance
The client accepts the priced change in writing before the work goes ahead — again, this can be as simple as a reply confirming agreement, not a formal legal document. What matters is that there's a clear record of what was agreed and at what price.
This step is what prevents the most common dispute at final account stage: one party remembering an instruction as included in the original price and the other remembering it as a separately agreed extra.
Updating the programme, not just the price
A variation often has a knock-on effect on the programme as well as the price — extra time for the change itself, and sometimes a delay to work behind it if trades have to wait. A properly controlled variation records both impacts, so nobody is surprised by a finish date moving as well as the final total.
Skipping the programme impact and only tracking the cost is a common shortcut that leaves the client with an accurate final bill but no warning that the completion date has also shifted.
Keeping a running total visible throughout
A well-run job keeps a visible running total of the original contract sum plus every accepted variation, updated as changes are agreed rather than reconstructed at the end. Either party should be able to ask for this total at any point and get an answer that matches their own records.
This running total is what turns variations from a source of anxiety into a manageable, transparent part of the project — everyone knows where the number stands at any given week.
Common questions
Does every small change need a formal variation?+
It needs recording in some form, even briefly, but the process can scale with the size of the change — a quick written confirmation for something minor, a fuller pricing exercise for something substantial.
What if a change is discovered mid-job, like rot behind a wall?+
The same process applies: raise it, price the impact, get it accepted in writing, then proceed. Discovering an issue doesn't remove the need for this step, even under time pressure to keep the job moving.
Who usually spots the need for variations — client or builder?+
Both. Clients often change their mind on finishes or layout once they can see the space; builders often uncover unforeseen conditions once walls or floors are opened up. Either source should go through the same written process.
Ask how we handle variations before you sign
Every change on our jobs is raised, priced and agreed in writing before it proceeds, so the final account has no surprises.