A variation is any change to the agreed scope — extra work, omitted work, or a change in specification — and variations are where profit quietly leaks away on a badly-run job. The single most important habit is to price and record each variation as it arises, in writing, and to get it agreed before proceeding wherever possible. Work done on a nod and priced at the final account is work you may struggle to recover in full.
A variation register keeps this under control. Each change is a distinct, dated item with its own value and status — approved or pending — so the contract sum is always the original plus the running total of approved variations. That means no surprises at the end, and a clear record if a value is ever disputed.
ConstructQS tracks variations against the original estimate, separating approved from pending, and folds them into the project's commercial position so tender value, cost and margin stay current as the job changes on the ground.