Construction Contract

A construction contract is the agreement in which a contractor undertakes to create a physical work, such as a renovation, extension, refurbishment or new-build project. For the client, this is not an administrative attachment to the quotation, but the document that determines exactly what will be built, at what price, within what timeframe and with what allocation of risk.

In construction, disputes rarely arise over whether work was done. They arise over what was or was not included, when something should have been finished, who bears the delay and whether an extra invoice is justified. A strong construction contract brings those discussions forward, before execution starts.

The core is simple: a good construction contract describes not only the work, but also what happens if the work changes, runs late or contains defects.

What is included in a construction contract?

A useful contract makes the quotation legally concrete. At minimum, it should state who the parties are, what work will be carried out, which documents take precedence, what the contract sum is, when payment instalments are due and when the work must be completed.

The technical appendices are just as important as the contract text. Think of drawings, specifications, material lists, calculation, planning, warranties and any general terms and conditions. If those documents are not explicitly part of the agreement, room remains for later disputes about finish level, quality and price.

Why oral agreements are dangerous

An oral construction contract can be legally valid. The problem is evidentiary. In a dispute, you must prove exactly what was agreed. That is difficult if the arrangements are spread across phone calls, loose WhatsApp messages and a high-level quotation.

Without written documentation, you mainly run risk on three points:

• Scope: the contractor argues that certain work was not included.

• Planning: a stated end date later turns out to be only an expectation.

• Costs: changes are invoiced as variations, while no clear price agreement was made in advance.

The most important contract choices

The quality of a construction contract is not in its length, but in the choices recorded in black and white. These elements determine most of the financial risk in practice.

Element	What you record	Why it matters
Scope of work	Drawings, technical description, materials and exclusions.	Prevents disputes about what is or is not included in the price.
Price	Fixed contract sum, target price or cost-plus work.	Determines who bears the risk of setbacks.
Planning	Start date, construction period, completion date and delay penalty.	Makes delay measurable and enforceable.
Variations	When a change is allowed, who approves it and how the price is set.	Protects against surprise invoices.
Completion	Procedure, snagging items, repair periods and warranties.	Prevents defects from remaining unresolved after payment.

Price: fixed contract sum, target price or cost-plus

The pricing model is one of the most important choices in the contract. A low quotation may look attractive, but without a clear pricing model you do not know which risk you are accepting.

Fixed contract sum

With a fixed contract sum, you agree a total price for the described work. This gives the most budget certainty, provided the scope is sharp. In principle, the contractor bears the risk of normal setbacks within the agreed work.

Target price

A target price is a serious estimate, not a non-binding guess. If the target price is likely to be exceeded by more than 10%, the contractor must warn the client in time, unless the parties agreed otherwise. For clients this can be useful, but it is less safe than a fixed contract sum.

Cost-plus work

With cost-plus work, you pay based on hours, materials and mark-ups. That can make sense for unpredictable work, but the financial risk lies largely with the client. Therefore record hourly rates, mark-up percentages, reporting and a budget cap.

Variations: use article 7:755 Dutch Civil Code to your advantage

Variations are one of the biggest sources of budget overruns. Article 7:755 of the Dutch Civil Code protects the client: in principle, the contractor can only request a price increase for additional work if they warned in time about the need for that price increase. That warning is not required if the client should have understood the price increase by themselves.

Make this practical in the contract. Agree that variations may only be carried out after written approval, with a description, price, impact on planning and any consequences for warranties. This prevents an oral request on site from later becoming a large invoice.

Planning: watch out for workable working days

A schedule sounds concrete until the contract states that the construction period is expressed in workable working days. Days with frost, heavy rain, storm or other circumstances may then fall outside the construction period. That can be justified for outdoor work, but it makes the end date less firm.

If you want real certainty, record a specific completion date and define exactly when postponement is allowed. Link that to a reasonable penalty or compensation for attributable delay. Without a consequence, a deadline is mainly an expectation.

General terms: UAV 2012, AVA 2013 and Wkb

Many construction contracts refer to general terms and conditions. That reference often determines the procedure for changes, liability, completion, payment and disputes.

• UAV 2012: widely used for commercial and larger construction projects. Pay close attention to the allocation of design responsibility, site supervision and variation procedures.

• AVA 2013: more often used for consumer assignments and smaller works. These terms are generally more accessible for private clients.

• Quality Assurance for Building Act (Wkb): strengthens the position of private clients in certain areas, including information, liability and the completion file. Check whether the contract aligns with it.

Do not accept general terms as an appendix nobody reads. Check whether they fit the project and whether deviations are clearly stated in the construction contract.

Checklist before signing

Only sign once these points are explicitly arranged:

1. Are the quotation, drawings, technical description and material choices part of the contract?

2. Is it clear what is excluded from the price?

3. Is the pricing model named: fixed contract sum, target price or cost-plus?

4. Are payment instalments linked to concrete progress?

5. Are variations only allowed after written approval with price and schedule impact?

6. Is there a specific completion date or a tightly defined construction period?

7. Is there a reasonable penalty or compensation for attributable delay?

8. Are completion, snagging items, warranties and maintenance period worked out?

9. Is it clear which general terms apply and which provisions deviate from them?

Conclusion

A construction contract is the steering mechanism of a construction project. The quotation says roughly what something costs; the contract determines who bears risk when reality deviates from expectation. Whoever records in advance what will be built, how changes are approved and when the work must be finished prevents the building site from later becoming the negotiating table.