Variations in a private building contract: agreed, necessary, ordered

Before discussing a variation, the client must know which regime applies. The question is not theoretical: the answer determines the form of the authorisation, the right to payment and the limit beyond which the contract can break down.

Regime	Who wants it	Price rule	Limit	Article
Agreed variations	the parties, often on the contractor's proposal	at a global price, no payment unless otherwise agreed	authorisation to be proved in writing	1659 Civil Code
Necessary variations	the work itself, to be carried out to a proper standard	failing agreement, the court determines them	beyond one sixth, the contractor may withdraw	1660 Civil Code
Variations ordered by the client	the client	payment due even at a global price	within one sixth, unless there are substantial changes	1661 Civil Code

The starting rule protects the client. "The contractor may not make variations to the agreed manner of the work unless the client has authorised them." And further: "The authorisation must be proved in writing" (art. 1659 Civil Code; unofficial translation, as are all quotations in this article). A variation carried out without written authorisation is not, in principle, a cost the client must bear.

With a lump-sum price (a corpo) the protection is even stronger. If the price of the whole work has been fixed globally, the contractor, even for authorised variations, "is not entitled to payment for the variations or additions, unless otherwise agreed". The practical consequence is clear: in a lump-sum contract, a variation order containing a price signed by the client may count as that agreement to the contrary. It should be signed knowing that it opens up a cost, not as a courtesy on site.

The choice between lump sum and measurement therefore shapes the entire variations regime. In a measured contract (a misura) additional quantities are paid at the unit rates; in a lump-sum contract the price pays for the defined scope. The differences between the two forms, and how to draft the contract, are explained in the article on lump-sum vs measured contracts.

Some variations nobody wants: good practice imposes them. Ground different from what was expected, an inaccurate design detail, a constraint discovered during the works. If the parties do not agree, "it is for the court to determine the variations to be introduced and the corresponding variations in price" (art. 1660 Civil Code).

One sixth marks the limit of the contract's resilience. If the amount of the variations "exceeds one sixth of the total agreed price", the contractor may withdraw from the contract and obtain "fair compensation". If the variations are "of considerable size", it is the client who may withdraw, paying "fair compensation". For the budget, this means that a series of unmanaged necessary variations can lead not only to a higher cost but to losing the contractor halfway through the works.

The remedy lies before the works begin. Necessary variations almost always arise from what the design did not investigate or did not describe. Surveys of the ground and of the existing building, a complete construction design and a contingency reserve sized for the stage reached reduce the likelihood of ending up in court.

The client can change their mind, within a limit. They may make variations to the design "provided their amount does not exceed one sixth of the total agreed price", and the contractor is entitled to payment for the additional work "even if the price of the work had been fixed globally" (art. 1661 Civil Code). It is the reverse of art. 1659: when the initiative is the client's, the lump-sum price does not protect them.

The limit does not cover everything. The provision does not apply when the variations "involve substantial changes to the nature of the work or to the quantities in the individual categories of work". A variation that transforms the work, or doubles a category of work, falls outside the art. 1661 mechanism and returns to the ground of agreement between the parties.

One sixth is counted cumulatively. According to the ANCE guide (ANCE being the national builders' association) on managing variations in private contracts (April 2024), the one sixth is calculated by adding up all the variations, not variation by variation. Keeping a running total is therefore a budget necessity: once the one sixth is exceeded, the contractor is no longer bound to carry out work on the terms of art. 1661, and every new request becomes a negotiation.

The direttore dei lavori (the works director) is not, in itself, the client's wallet. On ANCE's reading, the works director represents the client only on technical matters; their decisions on prices, variations and new work do not bind the client without an express delegation. The client may approve variations in writing "also through their own works director (if specifically delegated to do so)".

The delegation must be written, and limited. A clause in the works direction contract, repeated in the specification (capitolato), stating who may authorise a variation, up to what individual and cumulative amount and with what duty to inform the client, closes the door to most disputes. Without a delegation, a variation agreed at a meeting by the works director alone remains an open discussion between client and contractor, not an accepted cost.

The best application of arts. 1659 to 1661 is a written procedure, set out in the contract before the works. Its effect on the budget comes down to four steps.

1. The request. Every change, whether it comes from the client, the designer, the works director or the contractor, is described on a numbered form stating its origin, the work items affected and the presumed regime: agreed, necessary or ordered.

2. The quantification. The contractor states the price, up or down, and the effect on the programme. Reductions are tracked with the same rigour as increases: an omitted item that is not deducted is a hidden cost. If rates not provided for in the contract are needed, they are built up from a documented analysis; the technique is described in the article on the agreed new rates record.

3. The decision. The client, or whoever holds a written delegation, authorises the change and accepts the price on the same document, dated and signed. It is this signature that satisfies the written proof required by art. 1659.

4. Execution, and only then the invoice. No modified work starts before the signature. In a genuine emergency, an immediate written authorisation, even by email, followed by the price within a deadline set in the contract, is worth more than a verbal agreement.

Document	Minimum content	Who signs
Variation form	number, description, origin, presumed regime, work items affected	whoever proposes the change
Price offer	amount excluding VAT, up or down, effect on the programme	contractor
Authorisation	agreement on change and price, date	client or delegate in writing
Variations register	running total of approved variations and those under discussion, share of the one sixth used	client or client's adviser

The register feeds directly into the dashboard described in the article on tracking the final cost during the works. Signed forms go on the approved variations line, those quantified but not signed on the variations under discussion line, at their probable amount.

The example is entirely fictional and serves only to show the calculation. A client awards the refurbishment of an office building to a contractor, on a lump-sum basis, for a total agreed price of 900,000 euros, excluding VAT.

Item	Calculation	Amount
Total agreed price	contract figure	900,000 euros
One sixth of the price	900,000 / 6	150,000 euros
Ordered variation 1: different room layout	signed form	60,000 euros
Ordered variation 2: upgraded air-conditioning system	signed form	55,000 euros
Cumulative ordered variations	60,000 + 55,000	115,000 euros
Remaining share of the one sixth	150,000 - 115,000	35,000 euros

The client is considering a third variation of 50,000 euros. The cumulative total would rise to 165,000 euros, above the one sixth of 150,000: the contractor would no longer be bound to carry it out on the terms of art. 1661. Knowing this before asking allows a choice: reduce its scope below 35,000 euros, negotiate it as a separate agreement, or drop it.

A variation proposed by the contractor follows another logic. If the contractor suggests a different material for its own convenience and the client authorises it in writing without agreeing a price, no payment is due in a lump-sum contract (art. 1659). If, on the other hand, the form carries a signed price, that price will normally be due: the signature may count as an agreement to the contrary.

A contract variation is not the same as a variation to the building permit (titolo edilizio). The first changes what the contractor must carry out and how much is paid; the second changes what the authority has permitted to be built. The same change may require both, and the second has its own costs and timescales, covered in the article on permit variations. The variation form should state whether the change affects the permit, because administrative delay is itself a cost.

A new rate is a tool, not a regime. It values a work item the contract does not provide for, in any of the three regimes. The regime says whether the variation is due and who pays for it; the new rate says what it is worth.

In public works the framework is different. The Civil Code gives way to the public contracts code, with its own limits, funding and approvals, covered in the article on how the contracting authority funds variations during the works.

The text helps the client, but the dispute turns on proof. Who asked for the change, who accepted it, at what price: these are the facts argued over. Ambiguous messages, a site record noting a change without reservation, payments on account made without objection can all be used against the client.

Three reflexes reduce the risk. Dispute in writing, and at once, every invoice that contains unauthorised work. Have the site records note that a change under discussion remains subject to written authorisation and price. Never pay for a variation "to keep things moving" without a document fixing its amount. In the dashboard, a disputed variation stays recorded at its probable amount; the costs of disputes and any exit from the contract through termination under art. 1671 are covered in Claims, disputes and termination: the costs you do not see.