The Wkb handover file: what installers need to supply

The project is done, the client wants the handover and the file still needs pulling together. Photos are on four installers' phones, the rating plates were never photographed and the commissioning report is in someone's inbox. Since the Dutch Building Quality Assurance Act (Wet kwaliteitsborging voor het bouwen, Wkb) came into force on 1 January 2024, the contractor has to give the client a file at handover. For an installation company that usually means: your part has to be complete.

This article covers what goes in, which part falls to the installer and how to let the file grow while the work happens. It is not legal advice. What applies to your job depends on the contract and the type of work.

What the law requires

Article 7:757a of the Dutch Civil Code requires the contractor, when reporting that the work is ready for handover, to give the client a file. The file must show how the contractor fulfilled the contract and contains at least:

• drawings and calculations of the building and the associated installations;
• a description of the materials and installations used;
• the uses of the building;
• the information and documents needed for use and maintenance.

Three things to know. The obligation applies to construction contracts concluded from 1 January 2024. It applies to private and business clients alike; the Dutch name "consumentendossier" (consumer file) is misleading. And client and contractor may agree in the contract to handle the file differently. If nothing is agreed, the statutory obligation applies. NPR 8092, the Dutch practice guideline for the consumer file, gives a practical interpretation. Source: Informatiepunt Leefomgeving, in Dutch.

The consumer file and the file for the authorities

The two are often confused.

The consumer file, also called the handover file, goes to the client. It covers use, maintenance and insight into what was delivered. It applies to construction contracts unless agreed otherwise.

The file for the competent authority (dossier bevoegd gezag) goes to the municipality on completion. It shows that the building meets the technical building regulations. It belongs to buildings that fall under quality assurance, such as new builds in consequence class 1.

At the time of writing, renovation in consequence class 1 does not yet fall under quality assurance; its introduction has been postponed without a new date (Bouwend Nederland, in Dutch). If you keep the consumer file up to date, you already have much of the input for the authorities' file.

Why the file is also your evidence

The Wkb also changed liability after handover. For construction work, the contractor is liable for defects not discovered at handover, unless those defects cannot be attributed to the contractor (Article 7:758(4) of the Dutch Civil Code). With a private client, this cannot be set aside to the client's disadvantage.

For an installer, that means photos of pipework before the ceiling is closed, readings taken during commissioning and the models actually installed are not just file material. They are what you show when there is a leak or a fault two years later.

What an installer supplies

Exactly what belongs in your part varies by job and by type of installation. A workable baseline:

• As-built drawings and diagrams: pipe routes, circuit schedule, schematics as installed.
• Installations and materials used: make, model and serial number per unit, pipe systems used.
• Measurement and commissioning data: ventilation balancing report, pressure tests, readings at handover.
• Inspection and handover documents that apply to the installation, such as an inspection report for the electrical installation.
• Use and maintenance: manuals, maintenance instructions and intervals, warranty terms.
• Photos of concealed work: pipework, penetrations and connections before they are covered up.

If you work as a subcontractor, ask at the start in what format the main contractor wants your part. If you work directly for the client, you are the contractor and the whole file is yours.

Where it goes wrong

The file starts at handover. Then everything has to be tracked down, and photos sit on separate phones without a date or room.

The models on paper are not the models in the building. A different unit was supplied during the project because the original was unavailable. The file shows the model from the quote.

Serial numbers and readings are missing. They can only be captured properly on the day. Afterwards someone has to go back to site.

Everyone supplies a different format: PDF, a photo of a PDF, Excel, an email with an attachment. The project manager converts it all.

Letting the file grow during the project

The fix is organisational first: record things as the work happens, in one place, linked to project and room. The digital job sheet is the natural carrier for that. On top of it, AI is useful in four places.

Sorting photos. Installers' photos are filed by project, room and part of the installation. A photo of the meter cupboard ends up with the meter cupboard, not in a "misc" folder.

Reading rating plates. Make, model and serial number are read from the photo and set next to the model in the quote. If they differ, the project manager is alerted.

Tracking completeness. For each type of installation there is a list of what belongs in the file. During the project the system shows what is still missing: no commissioning report yet, no photo of the penetration in the fire-resistant wall.

Compiling. At handover the file is assembled from what has already been recorded, in the format the main contractor or client asks for.

What AI does not do here: judge whether your installation complies with the rules, or fill in data that was never recorded. A missing reading stays a missing reading. The project manager checks and signs. How to take this kind of work off the office further is in automating admin for an installation company.

What to measure

• Hours per project spent compiling the file, now and after the change.
• How often an installer has to go back for data missing at handover.
• How many rounds of resubmission the main contractor needs before accepting the file.
• Days between completion notice and complete file.

Where to start

The handover file is a legal obligation, but for an installation company it is mainly a recording problem. Record as the work happens and the file is largely ready at handover. Start at handover and you spend a long time searching, then still miss data that can only be collected on site.

Is the file one of several places where your office gets stuck? In the AI Opportunity Audit we put those places side by side and work out what tackling them delivers. More for your sector is on the installation companies page.