Ask anyone whose build ran over what caused it and you will rarely get one answer. You get a shrug and a list: the client moved a wall, the tiles changed, the soil was worse than expected, the windows got bigger.
None of those were unreasonable. What made them expensive is that each was agreed in a two-minute conversation on site, priced afterwards, and never compared to anything.
A variation is a contract change
That is the whole point people skip. Moving a door is not a detail. It is an amendment to what was agreed, and it changes at least one of three things: cost, time, or what was in the original scope.
Treating it as a conversation rather than a change is what makes the final bill a surprise.
The minimum a variation needs
Four things, and they fit on a phone note:
- What is changing, in one sentence.
- Who asked for it, and the date.
- What it costs: materials, labour, and anything it makes redundant that has already been paid for.
- What it does to the programme: days added, or none.
Then: agreed by the person paying, in writing, before the work starts. A message saying "yes, go ahead, +KES 40,000, three days" is a valid record. A verbal yes at 7am is not.
The one everybody forgets
Work that has to be undone. If a wall has been built and is now moving, the cost is not the new wall. It is the new wall, plus the demolition, plus the material already spent on the old one.
A variation priced only forwards is under-priced almost every time.
Keep a running list
One list, in order, with a running total against the original contract sum. Nothing complicated. date, what changed, who asked, cost, days.
The value is not any single row. It is that in week ten somebody can look at the bottom line and say: we are eleven variations in and 8% above the contract sum. That sentence, said in week ten, changes decisions. The same sentence at handover only assigns blame.
Say the number out loud, early
The hardest part of this is social, not administrative. Nobody wants to interrupt a good working relationship to say that the last three changes have added up.
But the alternative is saying it at the end, when the number is much larger and the client has already spent it. Every contractor who has been through that once starts keeping the list.
For the person paying
Ask for the running variation total at every site meeting. If nobody can produce it, that is the finding, not the number.
And be suspicious of your own small changes. Individually they are nothing. Fourteen of them, each too small to be worth writing down, is exactly how a budget goes without anyone deciding to spend the money.
What makes a variation order valid
A variation is only worth the paper it is written on if it can be pointed at later. Four conditions, all of them ordinary:
It was instructed by someone entitled to instruct it. On most private builds that is the client or the architect acting for them. A change agreed between a fundi and whoever happened to be on site is not an instruction, however sensible the change was.
It was recorded before the work started. A variation order written after the wall is up is not an approval, it is a claim. The whole value of the document is that the person paying got to say no while no still meant something.
It carries a price and a time effect. "We will agree the cost later" is the single most expensive sentence on a construction site. Later is after the work is done, which is the one moment at which the client has no leverage at all.
It is reflected in the baseline. An approved variation that never makes it into the bill of quantities leaves you comparing actual spend to a plan that no longer describes the building.
Who pays for a variation nobody asked for
Three situations get confused, and they settle very differently.
The client changed their mind. The client pays. This is the honest, ordinary case, and it is the one variation procedure exists to price fairly rather than to prevent.
The design was incomplete or wrong. Work that had to be redone because a detail did not resolve is not a client change. Where it lands depends on the contract and on who produced the detail, and it is worth establishing before the argument, not during it.
Conditions turned out to be different. Rock where soil was expected, a water table nobody tested for. This is why a contingency exists, and why the ground investigation that felt expensive at the start rarely does by the end.
The contractor made an error. Rework caused by work not built to the drawing is the contractor's cost. It is still worth recording as a variation with a zero client cost, because otherwise the material and time it consumed shows up later as an unexplained overrun on an element that was never over-specified.
Price a variation both ways
The commonest under-pricing is forward-only. A change has four components and most notes capture one:
- What the new work costs: materials, labour, plant.
- What the abandoned work already cost: the wall built, the slab poured, the tiles cut.
- The demolition or making good. Removing what is being replaced is work somebody does and material somebody disposes of.
- The knock-on: a moved wall that shifts a window, a door, an electrical run and a section of the roof. The single most common reason a variation is cheaper on the note than on the invoice.
Against that, subtract what genuinely comes out: an omitted variation is a credit, and credits have a habit of going unclaimed while additions never do.
A worked example
A client moves a bedroom wall 600mm, in week nine, standing in the room.
Priced the way it is usually priced: blockwork and plaster for a short wall. A small number, said out loud, and agreed.
Priced properly: the existing wall is demolished and disposed of, the blockwork and mortar already in it are written off, the new wall is built, the floor screed is patched, one electrical socket and its conduit move, the door frame position changes, the plaster and paint to two rooms is made good, and the plumber loses a day waiting for the wall to cure. Plus two days on the programme.
Neither number is dishonest. The first is simply not the cost of the decision. Everyone involved finds this out on the same invoice, and the disagreement that follows is really a disagreement about which of the two conversations happened in week nine.
The running total, and where it lives
The list itself is the mechanism, and the format matters less than that it is one list rather than messages in four threads. Date, description, who instructed, cost, days, running total against the contract sum.
Two disciplines make it work. It is reviewed at every site meeting, out loud, by both sides, because a list nobody reads is a diary, not a control. And the running total is expressed as a percentage of the contract sum, because "KES 640,000 of variations" means nothing on its own and "eleven per cent above contract" means something to everybody in the room.
For anyone running several projects, this is the point where a notebook stops scaling and construction cost control software earns its cost: variations posted against the budget as they are approved, the adjusted contract sum recalculating itself, and the same figure visible to the client and the contractor instead of two versions kept separately. The discipline is identical either way. See what a bill of quantities is for for the baseline it has to be measured against.
Common questions
What makes a variation order valid?
An instruction from someone entitled to give it, recorded in writing before the work starts, with a price and a programme effect attached, and carried through into the project baseline. A verbal agreement on site fails three of those four.
How do I approve a variation without losing control of the budget?
Approve against the running total, not against the item. The question is never "is KES 40,000 reasonable for this". It is "are we willing to be eleven per cent over contract, because that is what approving this makes us". The second question is answerable, and it is the one a running list puts in front of you.
Who pays for a variation the client did not ask for?
It depends on the cause: incomplete design, changed ground conditions and contractor error each land differently, and the contract decides. Record it as a variation regardless, with the cost attributed, so the final account is a reading of a list rather than a reconstruction from memory.
Can a contractor refuse a variation?
Generally they can decline work that is materially outside the agreed scope, and they can price it freely because there is no competition at that point. This is the practical reason to resolve specification before signing rather than after: every change made mid-build is bought in a market of one.
How many variations is too many?
There is no number. There is a percentage, and it is worth deciding it at the start: at what point above the contract sum does the client want to stop and review the whole budget rather than approve the next item? Builds that set that threshold in advance usually stop near it. Builds that do not, do not stop.
Should small changes be written down too?
Yes, and they are the ones this article is about. Large variations get priced because they are obviously worth pricing. Budgets are lost in the fourteen changes that were each too small to be worth the trouble, which is exactly what makes the total invisible until it is spent.