Do I need planning permission to add an extension to my house in Belgium?

Contents

When is planning permission required for an extension?

Cases where an extension is exempt from permit requirements (but not from town-planning rules)

Risks of unauthorized extension

When is planning permission required for an extension?

In Belgium, the general rule is simple: as soon as you modify the volume, appearance or structure of your home, planning permission is required. Where it gets tricky is when you get into the exceptions... but let's stick to the obvious first.

1. When the extension increases the volume or surface area of the building

An extension that creates additional living space- bedroom, veranda, office, enlarged kitchen, courtyard extension - almost always requires a permit. The larger the extension, the more stringent the requirements (setbacks, height, siting, respect for neighbors, PEB, etc.).

2. When the extension affects stability or load-bearing walls

Opening a load-bearing wall to enlarge a room, creating a bay window, building a second-storey room... all of these have an impact on the structure: a permit is required, often with an architect registered with the Ordre.

3. When the external appearance is modified

Changing materials, transforming the rear facade, creating new openings or modifying the roof: even in an area not visible from the street, these works may require a permit according to regional regulations.

4. In the event of a change of use

Converting a garage into a studio, an annexe into a professional office or one of the attics into a dwelling is considered a change of use, and therefore subject to planning permission, even if the volume remains unchanged.

5. In special cases: single-storey extensions, inhabited annexes and durable constructions

An addition intended to be lived in (studio, bedroom, isolated office), a two-storey extension, or any building with "permanent" anchorage to the ground (masonry, foundations, framework) almost always falls within the scope of the permit, even for modest surfaces.

Small extensions limited in surface area

In many cases, a small annex (often just a few square meters) can be exempted from the permit requirement.

Typical examples:

• small laundry room adjoining the house;

• equipment room ;

• light storage space.

But beware: each region sets a maximum surface area, and exceeding it by even one square meter means that the project is subject to compulsory licensing.

Extensions located in courtyard and garden areas, not visible from the public space

When an extension is placed to the rear of the building, out of sight of the street, the procedure can be simplified.

This applies to annexes in the garden, small overhangs on the terrace, or certain structures leaning against the rear wall.

The authorities are more flexible when the visual impact on the neighborhood is low, but this does not exempt the :

• maximum height,

• installation,

• distance from party lines,

• respect for neighbors (shadows, views, easements).

Strict cumulative conditions

Permit exemption works on the "yes, but..." principle:
yes, you can build without a permit, but only if you meet all the conditions.

Among the most common:

• limited height (often 3 to 3.5 m depending on the case) ;

• annex built in harmonized materials ;

• annex attached to an existing façade ;

• no impact on stability ;

• no single-storey extension ;

• The building must be located within the permitted limits.

Missing a single condition = compulsory planning permission.

The preliminary urban planning declaration: an "in-between" not to be forgotten

Even if you don't need planning permission, you still need to declare certain works.
This is a simplified procedure whereby you notify the commune before building.

For example, it concerns :

• light annexes,

• some small verandas,

• non-visible extensions exceeding a minimum threshold.

This avoids any ambiguity and protects your project in the event of a future inspection.

Risks of unauthorized extension

Building an extension without planning permission is not always a recipe for disaster, but it does expose you to a number of very real risks. The key is not to panic, but to understand what you're risking... so you can act in good time.

A fine or compulsory regularization procedure

In Belgium, any extension carried out without a permit (or without a town-planning declaration) constitutes a town-planning offence.

The communes or the certifying officers may :

• impose a fine, which varies according to region, surface area, type of work and age.

The more recent the offence, the stricter the authorities can be. On the other hand, the town-planning prescription can sometimes be applied, but this depends on a number of criteria: age of the building, nature of the offence, available evidence, etc.

Complete lock-up in the event of sale of the property

This is the most common scenario: all is well... until you decide to sell and the notary asks for the Urban Planning Information (RU).

If they reveal a non-conforming extension, the sale may be :

• delayed,

• negotiated downwards,

• or blocked outright until regularization.

Many owners only discover their infringements when they are put up for sale: it's better to anticipate them.

Insurance or technical compliance problems

In the event of a claim (fire, seepage, collapse, etc.), the insurance company can :

• limit compensation,

• demand a structural survey, or even contest the assumption of part of the damage in the unauthorized extension.

Not to mention other obligations : PEB, fire safety, easements, stability... An unregulated extension leaves some grey areas.

An obligation to restore in extreme cases

It's rare, but possible: when the extension does not comply with any rule (prohibited siting, encroachment on an easement, harm to the neighborhood, total non-compliance with the CoDT or local bylaws), the administration can order :

• full compliance,

• or partial or total demolition.
  

These are extreme situations, but they do exist, and preventive regularization helps to avoid them.

Acting now means avoiding complications tomorrow. A well-planned regularization protects your property, your peace of mind and your future resale.

At Ubex, we take care of everything for you, from analysis to concrete solutions. Make an appointment with our experts, explain your situation, and let's move forward together towards stress-free compliance.

Author : CORNIL Olivier

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