A variation is a proposed change to what was originally agreed for a building project.
It may change the work, specification, price, timing, responsibility, completion criteria or payment structure. The important point is not the label. It is that both sides can see the original position, the proposed change and its consequences before the project moves on.
Reading as
Why variations happen
Building projects rarely follow the original plan without any change.
For example:
you ask for six additional sockets;
rotten joists are uncovered after the floor is lifted;
a specified product becomes unavailable;
an engineer changes a detail;
you choose a more expensive tile;
additional work is required after an inspection;
agreed work is removed;
the change affects the completion date.
A variation does not automatically mean the builder priced badly or the customer is being difficult. It is the commercial record of a change that needs to be understood.
What should a variation tell you?
Before accepting, you should be able to answer:
1What was originally agreed?
2What is now proposed?
3Why is the change needed or wanted?
4Is it optional, necessary or one of several possible solutions?
5What is the added cost or credit?
6What effect will it have on the programme?
7Will it alter later work or another milestone?
8Is additional project funding required?
9What happens if the change is not accepted?
If those answers are missing, ask before the changed work starts where practical.
What it means for you
For homeowners
If you asked for the change
Imagine you ask the electrician to add six sockets during first fix.
It is tempting to agree the request while standing on site and let the electrician continue. The problem arrives later when £780 appears on the invoice and you thought the sockets were included.
A better variation would record the six locations, the first-fix work item, labour and materials, the price, any effect on timing, your question or requested revision, and your final acceptance.
The purpose is not to make a simple change bureaucratic. It is to prevent a friendly, quick conversation becoming an expensive memory contest.
Can I reject a variation?
You can normally ask questions or request revision before deciding, subject to the actual project agreement and circumstances. Some changes are optional. Others may be necessary for the project to proceed safely or lawfully. There may also be more than one possible solution.
The builder should explain the practical consequence of not accepting. That might mean the original work continues, the affected work pauses, another solution is proposed or the project needs formal review.
Do not accept simply because work is waiting. Equally, do not ask the builder to carry on while postponing the commercial decision.
For builders
When to raise a variation
Raise a variation when the accepted basis of the project needs to change, including:
work is added, removed or materially altered;
price changes;
programme or completion date changes;
specification or material changes;
responsibility changes;
a completion criterion changes;
a milestone or payment allocation changes;
an accepted assumption proves incorrect and the contract permits adjustment.
Where practical, create and obtain acceptance before carrying out the changed work.
When it may not be a variation
Not every new record is a variation. It may instead be:
a clarification with no change to the agreed basis;
a progress update;
a customer selection already allowed within an agreed budget;
correction of the contractor’s non-compliant or defective work;
completion of work already included;
a project note;
a query requiring explanation before any change is proposed;
a non-financial amendment, depending on the project process.
Whether an omitted cost can be recovered is a contractual question. A contractor should not assume that forgetting to price included work turns it into a valid chargeable variation.
Recording it well
Record the variation as soon as a conversation becomes a proposed change. Important practice includes:
do not rely on the fact that the customer was present on site;
do not assume the cost is obvious;
distinguish a request from casual discussion;
state labour, materials, subcontractor, overhead or margin treatment as appropriate;
include any delay or resequencing consequence;
link evidence to the existing scope;
wait for the required acceptance where practicable;
if urgent work cannot wait, record why, what authority existed and what was done as soon as possible.
If changed work goes ahead without one
the customer believes it was already included;
price cannot be evidenced clearly;
funding has not been adjusted;
the programme impact is attributed to the wrong party;
later trades rely on an undocumented detail;
the contractor carries cost and recovery risk;
the customer loses the opportunity to choose an alternative;
the final account becomes a reconstruction exercise.
Now imagine excavation reveals an existing drain across the proposed foundation line.
The builder proposes a reroute costing £1,850 and adding one working day. A useful record would include photographs, a marked-up drawing, an explanation of why the original route cannot remain and any relevant professional or Building Control input.
You may still ask whether there is another workable option. The builder may respond or revise the proposal.
Rear extension, Faversham
Variation 01
Stage 2 · Drainage and slab
Agreed
What was agreed?
The existing foul drain stays on its current route
What is changing?
Reroute the drain around the extension and add an inspection chamber
Why is it changing?
Excavation found the drain crossing the new foundation line, so the original route cannot remain
What will it cost?
+£1,850, added to Stage 2
Will it affect the programme?
Adds one working day to Stage 2
Has it been agreed?
Yes. Accepted before the work went ahead
The same change, as both sides see it: what was agreed, what is changing, why, the cost and the effect on the dates.
The eventual decision remains linked to the drainage work rather than appearing months later as an unexplained extra.
Is every change chargeable?
No.
A record may be a clarification, normal progress, a selection already included within an allowance, or a correction of work that did not meet the agreed requirement.
A contractor cannot safely assume that forgetting to price included work makes it a valid additional charge. Equally, a customer cannot assume that requested additional work should be absorbed into the original price.
The accepted scope, contract, cause of the change and surrounding facts matter. Where the legal position is uncertain, obtain appropriate professional advice.
What accepting a variation does
Subject to the project agreement, accepting a variation may:
update scope or specification;
change price and funding requirements;
change the programme;
update milestones or criteria;
preserve a new agreed project version;
notify affected participants.
It does not mean Assurr has judged that the variation was technically necessary, fairly priced or legally recoverable.
What if we already agreed it verbally?
A verbal conversation may have legal significance, but it is a fragile project record. Important details are easily missed:
Did the figure include VAT?
Did it include making good?
Did the change add time?
Did it replace or add to the original item?
Was the speaker making a firm instruction or exploring an idea?
Bring the change into the shared record promptly. Do not wait until the final invoice.
How Assurr supports variations
Assurr keeps the change inside the project context:
the affected work remains visible;
original and proposed positions can be compared;
cost and time effects are shown;
drawings, photographs and supplier information can be attached;
questions and responses remain connected;
acceptance or revision is recorded;
the relevant milestone and project totals update when the accepted process allows;
the previous version remains in the history.
Assurr does not decide whether a variation is legally chargeable, technically necessary or fairly priced. It gives both sides a clearer basis for making and recording the decision.
Quick checklist
Before accepting a variation, check:
the exact change
the reason
original scope
price or credit
VAT treatment where relevant
timing effect
downstream effect
evidence or professional input
funding requirement
consequence of saying no
The best time to understand a variation is before changed work begins, while both sides still remember why it arose.