Planning rules in Uccle, Forest, Watermael-Boitsfort and Ixelles: how the municipalities differ

You are planning works in the south of Brussels and wondering whether the process will be the same in Uccle (Ukkel in Dutch), Forest (Vorst), Watermael-Boitsfort (Watermaal-Bosvoorde) or Ixelles (Elsene). The short answer: most of the substantive rules come from the Region, but each municipality has its own planning department, its own regulations, its own neighbourhood plans and its own protected heritage. This guide compares what the four municipal websites and the regional heritage website say, noting when we read them. Quotations from these pages are our translation from the French. The guide is no substitute for a written answer from your municipality's planning department.

Key points

• The framework is regional (CoBAT, the regional planning regulations, the regional land-use plan), but the permit is in principle granted by the municipality's "collège des bourgmestre et échevins", which adds its own regulations and plans (uccle.be, as of 03-10-2026).
• All four municipalities accept online applications through the regional MyPermit platform; paper applications are handed in by appointment or sent by registered letter, depending on the municipality.
• Protected heritage changes the procedure: the application is then examined by the Region's "fonctionnaire délégué" (patrimoine.brussels). Check your property's status before you sign a quote.
• The wording of the municipal pages varies from one municipality to another, and sometimes from one page to another (opening hours, windows): ask the department concerned and keep the answer in writing.

One set of regional rules, four municipal desks

In Brussels, the legal basis is the Brussels Spatial Planning Code (CoBAT; BWRO in Dutch). According to the municipality of Uccle, it governs planning, the regional and municipal planning regulations, permits, heritage protection and appeals. The same website describes the regional planning regulations (RRU) as the basic tool for examining any permit application, and the regional land-use plan (PRAS) as a plan that takes precedence over the special land-use plans (PPAS), which are the municipalities' neighbourhood plans.

What the municipality adds, according to its own pages: municipal planning regulations (on rainwater, for example), PPAS that set the rules for one or more blocks, subdivision permits (permis de lotir) that have regulatory force, and a "commission de concertation" (consultation committee) that gives an opinion on applications put to a public inquiry (enquête publique).

Who grants the planning permit (permis d'urbanisme)? The Uccle and Watermael-Boitsfort pages say the same thing: in general the "collège des bourgmestre et échevins" (the municipal board of mayor and aldermen, the municipality's executive), but in specified cases the "fonctionnaire délégué" (the regional planning official who decides in certain cases). Those cases include listed buildings and buildings on the safeguarding list (liste de sauvegarde), or buildings for which such a procedure is under way. The application then goes to Urban, the regional planning and heritage administration. For the procedure and the exemptions in detail, see our guide to the planning permit in Brussels.

Uccle: green character, zoned regulations and varied heritage

What the municipality says about its policy. The "Mission du Service Urbanisme" page (the planning department's mission) lists among its aims "preserving the green character of our municipality", making sure new projects fit well into their surroundings, and a mix of uses. This is a stated policy direction, not a rule that can be enforced against you on its own: what applies to your plot is set out in the plans and regulations below.

Submitting your application. The department is at rue de Stalle 77 and is open Monday to Friday from 8:00 to 16:00. Some of the municipality's pages say "by appointment only", others do not, so book an appointment before you go. Three routes are described: the MyPermit platform (Uccle has used it since November 2023), handing in the file by appointment with an immediate certificate of submission, or registered letter. Uccle also publishes a "document d'orientation" (guidance document) on the municipality's objectives and on how it assesses applications: it is worth reading before anyone draws up a design.

Regulations and plans listed. The "Instance communale" (municipal authority) page lists:

• a zoned municipal planning regulation (RCUZ) called "Grandes Avenues", which aims to enhance the architecture and appearance of plots fronting two major traffic routes. The published maps are titled Brugmann Nord and Brugmann Sud, plus two further maps (Est and Ouest), and the page says the regulation is in line with the objectives of the PRAS area of cultural, historical or aesthetic value or for embellishment;
• a municipal planning regulation on water management, adopted on 25 February 2016 and in force since 28 November 2016, which promotes the reuse and temporary storage of rainwater before it is discharged at a limited flow rate, and also covers the connection to the sewer;
• regulations on shop signs and on the opening of certain shops;
• a general map of the PPAS and a table of their requirements;
• Uccle's general building regulations of 1948 (Règlement général des bâtisses), which the municipality says have been partly repealed by more recent regulations.

So if your plot lies within the area covered by the zoned regulation (the municipality publishes a map of it), or if you change how water is managed on the plot, these texts may apply on top of the regional rules.

Works that need a permit, according to Uccle. The application page lists, among others: insulating a facade that can be seen from the street, or insulating a property less than 20 metres from a protected building; replacing windows if their appearance changes (the municipal board encourages wooden frames); repainting the facade if the colour or texture changes; putting up a garden shed of more than 9 m²; felling or pruning a tall-stemmed tree (application to the Service Vert, the green spaces department).

Heritage. On its heritage page, Uccle names the following as legally protected: the Papenkasteel castle, the Nekkersgat mill (spelt Neckersgat in the regional register), the Bloemenwerf house, the Kauwberg and the Crabbegat sunken lane. It adds that some buildings that are not remarkable in themselves also deserve to be preserved because of their place in the typology and history of the area.

After the permit. The municipality points out that failing to display the site notice on site, or failing to send the notice of commencement of works by registered letter to the municipal board and the fonctionnaire délégué, is a planning offence.

Forest: precise figures on applications and archives

The principle. Forest's website states that, as a principle, a permit is required for construction, demolition and alteration works, inside as well as outside, and that an exemption is the exception.

Submitting your application. Since 21 November 2023, planning permit applications can be submitted online through MyPermit. Paper applications are accepted by appointment only (by phone or by email to urbanisme@forest.brussels). A technical drop-in session without appointment, for general technical questions only, is listed on Mondays from 13:00 to 16:00. Forest is the only one of the four municipalities whose page we read gives the fees: as of 03-10-2026, the submission fee (taxe d'introduction) is €150 for any new planning permit application and €100 for a tree-felling application. It is paid when you submit (online at the virtual counter, or by electronic payment at the counter; credit cards are not accepted).

Planning information and pre-emption. Before putting a property up for sale, you should ask the municipality for the planning information (renseignements urbanistiques, Article 281 of CoBAT). The request is made through Irisbox, and the legal time limit is 30 days. Forest also mentions a pre-emption area linked to the "Wiels-sur-Senne" sustainable neighbourhood contract, with a map and a list of plots.

Archives. Forest lets you order a search for a property's files (€15 per address, €2 per document as a digital copy); owners must show a title deed. The municipality says its archives are very complete, but that some files may be missing.

What we did not find. The page we read mentions a municipal regulation on rainwater (PDF) and refers to the PRAS, but has neither a list of PPAS nor a municipal position on windows. Ask the department whether a plan or regulation applies to your street.

Watermael-Boitsfort: permits, windows and neighbourhood plans

Opening hours. The planning department is in the Maison Haute, on the first floor. The "Urbanisme" page gives opening hours on Mondays (9:30 to 12:00 and 13:30 to 15:30 from September to June, 8:30 to 13:00 in July and August), and states that files put to a public inquiry can be consulted by appointment only. The French version of the "Le permis d'urbanisme" (planning permit) page, however, describes a department open by appointment only, while further down saying that the department can be visited on Mondays at the same times. So the wording differs, sometimes within the same page: book an appointment by phone or by email (urbanisme@wb1170.brussels) before you go.

Submitting your application. Online through MyPermit, at the counter with an immediate certificate of submission, or by registered letter to the municipal board.

Time limits and fees. According to the permit page, the time taken to examine an application depends on several factors (year of construction, planning situation, subject of the application) and "can vary from 75 to 190 calendar days". Administrative fees depend on the subject and on the procedure. An asterisk indicates that windows, roof windows, garden sheds and tree felling are exempt from file fees and the municipal tax.

Windows. The municipality has a page on replacing windows: a permit is needed because the external appearance changes, and it states a preference for wood. The "Le permis d'urbanisme" page puts it differently: a permit for windows and doors visible from the street, "yes, if the appearance is changed (material, divisions, colour)". Ask for written confirmation rather than relying on just one of the two wordings.

Other cases listed. Repainting the facade identically (same colour and texture) does not need a permit; a change of colour or texture does. A garden shed is exempt under certain conditions (9 m² maximum, limited height, in the courtyard and garden zone, no departure from a plan or regulation).

Archives. The "Urbanisme" page lists archive searches (permits, authorisations and building plans) among the department's tasks; requests are made using a downloadable form, and the page we read does not give a fee.

Neighbourhood plans. The website lists eight PPAS: Souverain-Est partie Sud, Coin du Balai, Étangs de Boitsfort, Souverain-Ouest, Plateau Boitsfort, Wiener, Vallée de la Héronnière and Archiducs, as well as a "Varda" plan that the page presents as belonging to Ixelles. Look at the plan that covers your address before you design an extension.

Heritage. The regional register of protected heritage (August 2026 edition) includes, for example, the Logis-Floréal ensemble, listed as an ensemble and as a monument, with a final decision of 15 February 2001, and the church of Saint-Clément and its surroundings, listed as a site. If your property is in or near such an area, special rules may apply: see the section on protected buildings below.

Ixelles: a shorter page, several specialised units

Ixelles gets only a brief mention here, because its planning page mostly describes how the department is organised. The Aménagement du territoire (spatial planning) department is at chaussée d'Ixelles 172 (2nd floor), and the website states that the municipality can be visited by appointment only. The page distinguishes the permits secretariat, an EPB unit, a planning information unit, complaints and offences, and an urban planning and heritage unit (Planification urbaine et Patrimoine); it refers to MyPermit for online applications.

Ixelles also mentions three municipal grants (energy saving, rainwater recovery, small heritage) without setting out their status on the page we read: see our guide to Rénolution grants and municipal support. On the pages we read, we did not find a list of municipal planning regulations comparable to Uccle's.

Archives. The Ixelles Archives department offers free consultation, by appointment, of planning archives (plans and planning permits closed for at least two years). For a given property, consultation is reserved for the owner or the managing agent (syndic), and for people they have authorised.

Protected buildings, the inventory and protection zones: what changes for your house

This section is based on the regional heritage website and applies to all four municipalities; the statuses themselves (listing, the safeguarding list, protection zone, legal inventory) are explained in our guide to Brussels character houses. In short, a building that is listed or on the safeguarding list, or for which the procedure is under way, falls to the Region's fonctionnaire délégué, and a permit in its protection zone is subject to special publicity measures and to the opinion of the Commission royale des Monuments et des Sites (Royal Commission for Monuments and Sites) if it is likely to change the views towards and from that building. Inclusion in the legal inventory is not protection, but any permit application for the property then goes to the consultation committee (exemptions exist).

What varies locally. Uccle mentions a distance of 20 metres from a protected building in connection with insulation; the pages we read do not say whether this distance overlaps with the protection zone. The number of protected properties, on the other hand, differs markedly from one municipality to another (see below).

How to check. The register of protected heritage can be consulted as a list or on BruGIS, and the inventory records flag protected buildings in the "Statut juridique" (legal status) tab. By our own count of the entries in the register's PDF list (08/2026 edition), which is not a figure published by the Region, there are 113 entries for Uccle, 101 for Ixelles, 47 for Watermael-Boitsfort and 43 for Forest. An entry is not a building: a single ensemble (the Logis-Floréal in Watermael-Boitsfort, for example) can have several entries, and the list includes monuments, ensembles, sites, trees and properties whose protection procedure is under way. These figures say nothing about how strict the local rules are.

Comparison table

"Not stated" only means that we did not find the information on the pages we read, not that it does not exist.

Frequently asked questions

Will my project be handled the same way in two neighbouring municipalities?

Not necessarily. CoBAT and the regional regulations apply everywhere, but the PPAS, the municipal regulations, the protection areas and the department's practice differ. The pages we read show, for example, differing wording on windows in Watermael-Boitsfort, and zoned regulations specific to Uccle. Ask the department of the municipality where the property is located.

How do I find out whether my house is protected or included in the inventory?

The register of protected heritage, BruGIS and the inventory let you check this; the steps are set out in our guide to Brussels character houses. If in doubt, ask your municipality's planning department, which will confirm the status of your plot.

Can I find the old permits for my house?

The pages we read confirm this for three of the four municipalities, with different arrangements. Forest and Watermael-Boitsfort carry out the search on request, while Ixelles opens its planning archives for consultation (see the sections on these municipalities above); Uccle has an Archives section that we did not look at in detail. Forest charges for the search (€15 per address); Ixelles offers free consultation by appointment. Bring proof of ownership or the owner's authorisation. As of 03-10-2026, only the Forest page we read gives the submission fee: ask the department for the amount before you apply.

What are the risks of carrying out works without a permit?

According to the municipality of Uccle, a person for whom an official report of the offence has been drawn up is asked to apply for a regularisation permit (permis de régularisation), whose outcome is uncertain, and a fine is payable even if the regularisation succeeds. Penalties and restoring the site to its previous state are explained in our guide to the planning permit.

On 03-10-2026, the editorial team reread the pages of the planning departments of the municipalities of Uccle, Forest, Watermael-Boitsfort and Ixelles, as well as the pages of the regional heritage website (PDF register of August 2026, protection measures, legal inventory); the passages on the archives of Ixelles and Watermael-Boitsfort and on the protection zone were rechecked on 19-10-2026. The register counts are our own. Statuses, thresholds, fees and opening hours change, and sometimes differ from one page to another on the same website: check with your municipality's planning department before you submit anything or start any works.