Reviewing variations and additional costs in construction: when extra remuneration is owed, how section 1152 ABGB secures reasonable pay and what applies to unauthorised work.
BRANDAUER Rechtsanwälte
Salzburg law firm for real estate, construction and corporate law
Every matter is handled by a coordinated team of lawyers, legal staff and specialists. In construction cases we look at contract, evidence, deadlines and commercial consequences together.
During construction, plans change, unforeseen circumstances arise or new wishes are added. The contractor submits variation offers, bills time-and-material work or demands more at the end than originally agreed. Many clients then wonder what they really have to pay for.
The legal answer depends on whether it is additional work prompted by the customer or additional work carried out by the contractor on their own initiative. Whether a price was agreed is also decisive. The mere overrun of a cost estimate has to be considered separately from this.
This article explains when extra remuneration is owed, how variations differ from a cost estimate overrun and what matters with additional cost claims. From a lawyer’s perspective, the precise classification is worthwhile because it determines the amount of the justified claim.
Answer one or two questions about who prompted the work and the price agreement. You will receive an initial classification of the claim.
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The decisive question is whether you ordered an additional or changed service or whether the contractor did more on their own initiative.
If you ordered a change or extra service and agreed a price for it, you owe that price. Make sure the agreement clearly reflects the scope of the additional work so that no dispute arises later about what is owed. Record the order and the agreed price in writing.
Check the final invoice to confirm that only the additional work actually ordered and performed is billed.
If you ordered additional work without agreeing a price, a reasonable remuneration is deemed to have been agreed under section 1152 of the Austrian Civil Code (ABGB). The contractor therefore cannot demand any arbitrary amount but only the market-standard, reasonable remuneration for the work performed. The reasonableness has to be substantiated in case of dispute.
Have an excessive additional cost claim checked for reasonableness before you pay or refuse payment.
If the contractor carried out more without your order, there is no automatic claim to remuneration. Such a claim only comes into consideration if the additional work was necessary and served your predominant benefit or if you subsequently approved it. For purely unauthorised work you generally do not have to pay.
Check whether the work was actually necessary or whether you could have declined it. A flat additional cost claim has to be examined closely.
In construction, a distinction is made between changed work and additional work. Changed work exists where an originally agreed service is carried out in a different way, for example a different floor covering than planned. Additional work is work that was not contained in the original contract at all, for example an additional room.
Neither form on its own establishes a claim to extra remuneration. What is decisive is that the additional work is based on an instruction or order from the customer or is at least approved by them. Whatever the contractor does on their own initiative, without it being necessary or desired, is in principle at their own expense.
This has to be separated from a pure cost estimate overrun. There the service stays the same, only the originally estimated price is exceeded. That situation follows its own rules under section 1170a ABGB and must not be equated with additional work.
Extra remuneration is owed to the contractor if you commissioned a change or additional service. If you agreed a price for it, that price applies. Without a price agreement, a reasonable remuneration is deemed to have been agreed under section 1152 ABGB. The contractor can then only demand the market-standard remuneration, not any arbitrary amount.
If the contractor carried out more without an order, caution is required. A claim to remuneration in that case only exists exceptionally, for example if the additional work was necessary and served your predominant benefit or if you subsequently approved it. You generally do not have to pay for purely unauthorised work.
Anyone who wants to be on the safe side has additional work offered in writing before it is carried out and confirms the order only after review. This avoids later disputes about whether and how extra remuneration is owed.
Three situations that are often confused, each with its respective legal basis.
| Situation | What happened | Governing basis |
|---|---|---|
| Variation Changed or additional service | You commissioned additional work | Agreed price or reasonable remuneration (section 1152 ABGB) |
| Time and material Billing according to effort | Work agreed by hours and material | Proof of measurement and actual effort |
| Overrun Cost estimate exceeded | Same service, higher price than estimated | Rules on overruns (section 1170a ABGB) |
The classification determines the legal basis and the burden of proof. The overview does not replace a review of the individual case.
If ÖNORM B 2110 is agreed, it provides its own procedure for additional cost claims. The contractor must announce additional costs in principle and set them out comprehensibly as to amount. If they fail to give timely notice, this can impair their claim. Whether the ÖNORM applies follows from your contract.
Regardless of the ÖNORM, documentation is decisive. For time-and-material work, the measurement, hour records and material evidence are the basis of every invoice. Have these records presented to you and compare them with what was actually performed.
How the mere overrun of a cost estimate differs from this is explained in the article on the cost estimate exceeded. Where the contractor had to point out necessary additional costs, the article on the contractor’s warning duty helps. An overview is offered by our focus page on construction contract and remuneration.
Practical tip: Only confirm additional work once you have a comprehensible variation offer. A written order with a quantified price protects against surprising final invoices. With an excessive additional cost claim, a review before payment is worthwhile. Booking an initial consultation (72 euros) clarifies the situation quickly.
As a rule, no. Additional work carried out by the contractor on their own initiative only establishes a claim to remuneration exceptionally, for example if it was necessary and served your predominant benefit or if you subsequently approved it. For work performed purely on the contractor’s own initiative you generally do not have to pay.
If you ordered additional work without agreeing a price, a reasonable remuneration is deemed to have been agreed under section 1152 ABGB. The contractor can then only demand the market-standard, reasonable remuneration. An excessive claim has to be checked for reasonableness, in case of dispute often with the help of an expert.
No. A variation concerns a changed or additional service that goes beyond what was originally agreed. With a cost estimate overrun the service stays the same, only the estimated price is exceeded. That follows its own rules under section 1170a ABGB. The correct classification determines the legal basis.
The focus page on the construction contract, the due date of the remuneration and the rights of both sides.
When an overrun of the cost estimate is permissible and what rights you then have.
When the contractor must point out impending additional costs or defects and what applies in case of breach.
What ÖNORM B 2110 regulates and how its additional cost rules affect the construction contract.
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