Additional works

A single question, whose answer governs everything. It asks whether the work was provided for or not.

Was the work included in the contract.

If it appears in the specification or the schedule, it is due, whatever difficulty of execution is encountered.

If it does not, it constitutes additional work, however technically obvious it may be.

In a lump sum contract this is the only question that matters, since the lump sum covers only what was described, as the article on measured and lump sum explains.

In a measured contract a further distinction applies: a quantity greater than that foreseen is not additional work; it is an adjustment to the account.

Origin	Who requires it	Effect on price
Change of brief	The client	Priced variation
Unforeseen difficulty	Site conditions	Contractual valuation
Error in the documents	The design	Treatment under the contract
Work omitted from the schedule	The tender package	A new rate to be agreed

They do not engage the same responsibilities. An instructed change differs from an unforeseen difficulty.

A change requested by the client. The most legitimate origin, and the one that must be best documented.

A technical unforeseen. Discovered during execution, frequent in refurbishment on opening up existing fabric.

An omission in the package. A necessary work was not described, which engages the design team rather than the contractor.

Divergent interpretation. Each party maintains a different reading of the same wording, covered in the article on what an item must contain.

The third origin is the one least readily acknowledged, although recognising it early costs less than contesting it at length.

Three methods, in order of preference.

By reference to the schedule prices, where the additional work resembles them. This is the safest method, since it rests on prices bid in competition.

By build-up, reconstituting the price from its components, labour, materials and plant.

By negotiated agreement, where the first two do not apply.

The third method is the least favourable to the client, since it takes place outside competition, once the contractor is established on site.

Hence the value of a complete schedule: the more situations it covers, the more additional works can be valued by reference.

Four requirements, to be provided for in the contract documents. They frame the ordering and pricing of additional works.

Written form, without which each party will maintain its own version.

Identification of the authorised signatory, failing which requests from unauthorised persons bind the client.

Prior agreement on price, rather than discovering the amount at the final account.

The effect on the programme, often forgotten although additional work pushes back completion.

The third requirement is the most neglected in the pressure of the site, and it is the one that costs.

Three situations to set aside.

A greater quantity in a measured contract, which belongs to the final account.

An execution constraint the contractor should have foreseen, where the package mentioned it.

Remedying defective work, which falls under the obligation to build properly.

These three are regularly presented as additional works, and distinguishing them is part of the verification task.

Four rules.

Classify before valuing, without exception.

Require writing and prior agreement on price, including under pressure.

Value by reference to the schedule wherever possible.

Acknowledge an omission in the package where one exists, rather than contesting it at the price of a costlier dispute.