Hardly any construction project runs exactly as tendered. Variations are the rule, not the exception, and their management determines whether a project stays within budget or escalates.
What a variation is
A variation is an adjustment to the construction contract during execution, usually associated with a change in remuneration. It arises when services are carried out differently, additionally or not at all compared with what the contract originally provided.
Variations are normal and not a sign of poor planning. No bill of quantities can anticipate every eventuality of a construction project. What matters is not to avoid variations but to record, review and fairly assess them cleanly.
Why variations arise
- Changed requirements: the client wants a different or additional service.
- The unforeseen: ground, existing structures or weather deviate from the assumptions.
- Planning gaps: the tender was incomplete or ambiguous.
- Quantity deviations: the actual quantities differ from those tendered.
Especially in the existing network and under operations, as in railway and civil engineering, the unforeseen and quantity deviations occur frequently. All the more important is a procedure that deals with them in an orderly way.
How a variation is reviewed
Prevention and early steering
The most effective protection begins before the first variation: with a complete, unambiguous tender and realistic planning. The clearer the contract, the less room for dispute over what is actually owed.
In execution, speed and documentation are what count. Anyone who records variations immediately, reviews them before execution and records the decision prevents an unmanageable pile of disputed claims from building up at the end of the project.
The role of construction supervision
Construction supervision is close enough to events to be able to assess variations technically: it sees what is actually being built, knows the tender and can judge whether a service is really additional or was already owed.
It is therefore the natural body for the first variation review. It protects the client from unjustified claims and at the same time ensures that justified variations are processed fairly and promptly, which in turn does not slow down the construction process.
Variations with a disrupted construction process
Particularly delicate are variations that arise from a disrupted construction process: when hindrances, delays or missing pre-work throw the planned sequence into disarray. Here it is not about a single additional service but about the consequences of a disruption across the whole project.
Such claims are demanding to substantiate, because the contractor must prove the disruption, its cause and its concrete consequences. Without ongoing, verifiable documentation of the actual construction process, this can hardly be presented reliably after the fact.
This is precisely why prompt documentation by construction supervision is so valuable: it records when what happened and thereby creates the basis on which justified claims can be enforced and unjustified ones fended off.
For the client this means double security: they recognise early when a disruption is developing into a cost risk and can counteract, rather than being surprised at the end of construction by a large, hard-to-review claim.
Häufige Fragen
What is a variation in construction?
An adjustment to the construction contract during execution, usually with a change in remuneration, when services are carried out differently, additionally or not as tendered.
Are variations a bad sign?
No. No bill of quantities can anticipate every eventuality. What matters is orderly management that reviews and assesses variations cleanly.
How do you keep costs under control?
Through a complete tender, realistic planning and ongoing construction supervision that processes variations promptly and verifiably, instead of letting them pile up until the end of construction.
Edoé Lassey
Edoé Lassey führt die LND Ingenieure GmbH als Bauüberwacher und Ingenieur für Infrastruktur- und Tiefbau. Die zertifizierten Rollen Technischer Berechtigter, Sicherungsüberwacher, Schaltantragsteller und Bauvorlageberechtigung gehören zum Leistungskern.
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