The effect of a conversion notice in contracts for works

19 February 2026

The effect of a conversion notice in contracts for works

By Annemiek Noordermeer-van der Heide

Suppose a contractor has been engaged under a contract for works, but a problem arises during the execution of those works. Unfortunately, this happens quite often. If the parties are unable to resolve the issue together, it is advisable to consider legal steps. Below is a practical explanation and five useful tips.

Situation outline

The contractor was instructed to build an extension, but failed to deliver it in accordance with the agreed terms. The floor has not been properly finished and is uneven, negatively affecting both the finish and the functionality of the extension. Although window frames were installed, the agreed double glazing was not fitted. This has led to a dispute between the client and the contractor on several key points.

According to the client, the situation is clear and the agreements are unambiguous, but the contractor has a different interpretation of the contract. This difference in views may lead to further complications. For the client, it is now important to carefully follow the following three steps:

  • Collect documentation: gather all relevant documents, such as contracts, emails and photographs of the current state of the extension. This helps to clearly identify the agreements made and the existing shortcomings.
  • Communicate with the contractor: contact the contractor to discuss the disputed issues. Try to reach mutual understanding through discussion and look for solutions that are acceptable to both parties.
  • Seek legal advice: if no agreement can be reached, it is advisable to obtain legal advice.

What legal actions can be taken?

Notice of default

Sending a notice of default to the contractor is an important step in the process of enforcing proper performance of the works. This notice should be sent by registered letter, so that it can be proven that it has reached the contractor. In the letter, the contractor is requested to complete the works within a reasonable period or to carry out the necessary repairs.

It is essential to clearly describe the contractor’s remaining obligations in the notice of default. This includes a detailed description of the work still to be carried out, such as finishing the floor, installing the correct double glazing in the window frames, and remedying any unevenness. By formulating these obligations clearly, it becomes clear to the contractor what is expected of them.

Conversion notice

If the contractor does not respond within the set period or fails to carry out the works, they are in default. This means that the client is entitled to have the work completed or repaired by a third party and to recover the costs from the contractor.

In order to recover these costs, the client must, after sending the notice of default, send a conversion notice to the contractor. This notice converts the contractor’s obligation to perform into an obligation to pay damages. Until the conversion notice has been sent, the contractor retains the right to complete the works. However, once the conversion notice has been sent, that right is lost and the contractor is obliged to pay damages.

The damages must represent the value of the unfinished work, which is generally determined on the basis of replacement value. This means that the compensation should be based on what it would cost to have the work carried out by a third party. If the third party charges higher costs than those originally quoted by the contractor, this risk is borne by the contractor.

Engaging a third party

After engaging a third party, the contractor must be informed of the costs incurred. This can be done by sending a detailed invoice specifying the costs of the completed works and any repairs. The contractor is liable for these costs, as they have failed to fulfil their obligations. If the contractor refuses to pay the incurred costs, the client may be forced to initiate debt recovery proceedings. The real estate specialists at GMW lawyers can assist you with this.

Five practical tips

  1. Make clear agreements about the works to be carried out.
  2. Agree a clear contract price, such as a fixed price, a target price or a price based on hours worked.
  3. Record how long the works are expected to take; this provides clarity.
  4. Conclude a contract to which general terms and conditions apply, in order to prevent disputes.
  5. If you do not agree a contract price, at least agree a number of guiding principles in advance.

Contact and advice

If you have a dispute with a contractor and/or would like to know which contract or which general terms and conditions are most suitable for your situation, please feel free to contact me or one of the other real estate and tenancy specialists at GMW lawyers. We are happy to help.

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