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.