Extension permit: does it need a sunlight study?

Do I need an environmental permit for my extension?

An extension is often permit-free if it sits at the back of a home, is no deeper than 2.5 metres, no higher than the existing eaves line, stands within the rear-yard zone, and keeps sufficient distance from the plot boundary. If your plan does not meet all of these conditions, you need an environmental permit via Omgevingsloket.nl. The Environment Act (Omgevingswet) (in force since 1 January 2024) governs this through the Buildings (Living Environment) Decree (Bbl); for your specific situation the permit check at omgevingsloket.nl is decisive.

This article is about the permit-required category. If your extension needs an environmental permit, the municipality can require a sunlight study as an additional attachment. That happens more and more under the Environment Act (Omgevingswet), particularly in densely built cities such as The Hague, Rotterdam and Amsterdam. In the Ootmarsum case (3 July 2013, ECLI:NL:RVS:2013:191) the Council of State ruled that a municipality which fails to carry out a sunlight study before granting a permit breaches article 3:2 Awb (duty of careful preparation). Municipalities want to avoid that risk by requiring the study from the applicant.

Permit-free building: the limits in 2026

Permit-free building is relatively generous in the Netherlands. The national government states that, for a home with a back garden, the following is usually allowed without a permit. These values are indicative; municipalities can be stricter through the environment plan.

This is a heavily simplified representation. The exact rules are in the Buildings (Living Environment) Decree and in your municipality’s environment plan. The definitive test is the permit check at omgevingsloket.nl: a free digital decision tool that gives you the right outcome step by step.

When does the municipality require a sunlight study?

Not every permit application requires a sunlight study. The municipality assesses per project whether the chance of shadow nuisance is significant. In practice most Dutch municipalities use one of the following thresholds:

• Building height. Above 10 m (Rotterdam) or above the existing eaves line (many other municipalities) a sunlight study is a standard part of the submission set.
• Roof addition on a terraced house. Under RIS 180461, The Hague requires a sunlight study for every roof addition on a terraced house, regardless of height. The The Hague 50% rule is the direct reason.
• Large extension. Extensions deeper than 3 m (where 2.5 m is permit-free) routinely attract a sunlight request in densely built neighbourhoods, including in Eindhoven after the 2022 policy revision.
• New build on an empty plot. In most municipalities, all new build above the height of the surrounding existing buildings gets a sunlight assessment.

In cities that use the standard light TNO standard (the majority of the 342 Dutch municipalities) an assessment on the three test dates 19 February, 21 June and 21 October is sufficient. In The Hague, Rotterdam, Eindhoven and Krimpen aan den IJssel the local guideline applies on top. Schaduwplan tests automatically against all relevant standards at once.

The Environment Act since 1 January 2024: what changed

The Environment Act (Omgevingswet) (introduced on 1 January 2024) bundles 26 existing laws into a single system for the physical living environment. For an extension permit, three things change in practice.

1. One digital counter. You submit your permit application via Omgevingsloket.nl, no longer via the old digital Omgevingsloket (DSO) or municipal portals. The permit check up front determines whether a permit is needed.
2. The environment plan replaces the zoning plan. Every municipality draws up an environment plan that sets out the local rules. Sunlight is covered under article 2.1 of the Environment Act (Omgevingswet) and is governed by municipalities through this environment plan. Some municipalities explicitly require a sunlight study above a certain building height.
3. Shorter decision periods. The regular procedure has a decision period of 8 weeks, extendable once by 6 weeks. For complex projects this can run up to 6 months, but for standard extensions 8 weeks is the norm.

For you as the applicant, the most important practical impact is: the municipality may be stricter than the TNO standard if that is set out in the environment plan. Check the environment plan before you design, not only during the application. That way you prevent a design that would have worked elsewhere from failing on a local rule in your municipality.

Preventing objections from neighbours: map the sunlight up front

The fastest way to lose a permit application is an objection from the neighbours. Even if the municipality assesses your application favourably, your neighbours can object within six weeks of publication under article 6:7 Awb. If their objection is substantiated with a quantitative sunlight report, that can delay or revoke the permit. On 17 January 2024 the District Court of The Hague (ECLI:NL:RBDHA:2024:1206) even ordered the demolition of an already completed roof addition at 75 to 80% sunlight loss, even though the owner held an irrevocable permit.

The reverse route is also possible and more favourable: a sunlight report from your side, shared proactively with your neighbours before you submit, defuses many potential objections in advance. If your report shows that the sunlight loss stays below the light TNO standard (less than 2 sun hours per day) and outside the The Hague 50% threshold, an objection has little legal basis left. Your neighbours then see hard data, not a substantiated suspicion, and the dialogue shifts from conflict to execution.

Practical tip: add a sunlight report both to the permit application and to an accompanying neighbour letter. The municipality values the file as complete, and your neighbours have the information they need not to raise an objection. For a €29.95 report that is a sharp insurance against a €10,000-plus delay if the building permit is halted by an objection.

How Schaduwplan fits into a permit application

For a proactive homeowner or architect, Schaduwplan is primarily an iteration tool. Enter your address, draw the planned extension, change heights and depths until all measurement points meet the light TNO standard, and download the end result as a PDF report. Iteration costs nothing within the access period. An independent building consultant (HoeveelZon, HBA), by contrast, charges again for each redesign.

The final report contains the standard elements the municipality expects: a cover with the address and date, the assumptions (chosen standard, test dates, coordinate system), 3D sunlight diagrams side by side (current versus with extension), a TNO test table per measurement point, a methodology appendix with source references (3DBAG, BAG, AHN4), and a disclaimer. You add this report as an attachment to your Omgevingsloket application. The civil servant can see straight away whether your design meets the standard, without having to carry out the calculation themselves.

For architects who submit several permit applications a year, this becomes a fixed part of the portfolio. One Schaduwplan report per permit adds €29.95 to the invoice, versus €295 to €535 at a small building-advice firm — a 90% discount on the same attachment, with the freedom to refine the design iteratively before you submit the final version.