The terms of the contract may also impose limits on the power of the principal to direct variations. For example, if the contract expressly identifies work that is excluded from the contractor’s scope of work, the principal may not have the power to subsequently issue a variation directing the contractor to perform such work (unless it expressly receives the right to do so in the contract).
Generally, variations may not be directed after the works have achieved practical
CHANGES NOT DIRECTED BY THE PRINCIPAL
Most contracts contain provisions allowing the contractor to request a variation if it believes that there has been a change to the work entitling it to a variation.
For example, a change may arise due to a need to address design errors, to comply with changes in law or to incorporate additional scope. Some contracts may also allow the contractor to request a variation for its own convenience (although whether such a request will be considered is typically a matter reserved for the principal’s discretion).
EFFECTIVE CONTRACT ADMINISTRATION
Most construction contracts require that a variation be directed in writing. However, sometimes urgency will require the principal to give a verbal direction to vary the work.
This should be followed by (and a contractor should insist upon) written confirmation as soon as reasonably practicable so that the scope of what is required, and any other conditions that may be relevant, are clearly understood by all parties.
For a contractor who considers that a variation has been directed, prompt notification of this to the principal or superintendent can be particularly important if the relevant contract includes a time bar clause (that is, a clause which provides that the contractor will ‘forfeit’ any entitlement if it fails to notify and/or lodge its substantive claim within the time period provided for under the contract).