Why choose Avenir Renovations?
Why choose a storey addition with accessible roof terrace?
The storey addition allows you to transform your roof into a livable floor. When it comes to an accessible roof terrace, the benefits are even more numerous:
- Easy access for work
- Significant space gain without loss of land
- Reduced intervention times
- Possible creation of additional bright rooms (master suite, office, guest room...)
- Significant increase in your property value
It is a solution that is both aesthetic and functional, particularly suited to dense urban areas like Brussels, Liège, Antwerp, or Namur.
The steps of a project for an accessible roof terrace storey addition
The storey addition of an accessible roof terrace is a complex project that requires careful planning. Here are the main steps to follow:
Necessary work for an accessible roof terrace extension
A storey addition project involves several trades. Here are the main works to be planned:
- Possible demolition of the old roof
- Reinforcement of the load-bearing structure (walls, floors)
- Installation of the new framework (wood, metal, or concrete)
- Installation of the new roof and waterproofing
- Thermal and acoustic insulation (internal and/or external)
- Creation of internal partitions
- Carpentry work (doors, windows, stairs)
- Installation of floor and wall coverings
- Electricity (secondary panel, outlets, lighting)
- Plumbing (if bathroom or kitchen)
- Heating (radiators, underfloor heating, or heat pump)
- Painting, coatings, decoration
- Installation of custom furniture if necessary
- Outdoor fit-out of the roof if you wish to maintain terrace access
What budget to plan for an accessible roof terrace storey addition?
The cost of a storey addition varies according to several factors: surface area to be created, materials chosen, level of finish, accessibility of the site, geographical location... Here is a indicative table of average prices observed in Belgium:
| Type of storey addition | Average price per m² | Estimated total budget |
| Wood frame storey addition of 30 m² | 1,800 – 2,500 € | 54,000 – 75,000 € |
| Concrete storey addition of 30 m² | 2,500 – 3,500 € | 75,000 – 105,000 € |
| High-end fit-out storey addition of 30 m² | 3,000 – 4,000 € | 90,000 – 120,000 € |
Good to know: Good insulation and smart design can save on your future energy bills. Additionally, the value of your property generally increases by 15 to 30% after a storey addition.
What administrative steps are needed for a storey addition with accessible roof terrace in Belgium?
The storey addition is considered a major modification of the habitation. In Belgium, this generally involves:
1. Urban planning permit
Mandatory in almost all cases. It is submitted to the municipality. The file must include:
- Before/after plans
- A stability report
- An impact notice
- The technical description of the project
2. Architect's involvement
Belgian law requires the involvement of an architect for any major transformation affecting the structure of a building.
3. Compliance with the Walloon/Brussels housing code
Your project must comply with local urban planning rules (maximum height, alignment, overlooking, aesthetics, etc.) as well as habitability standards (ceiling height, ventilation, natural lighting...).
4. Declaration to the land registry
Once the work is completed, you must declare the new living area to the land registry, which may affect your property tax.
Why choose Avenir Rénovations Belgium?
We are much more than a general contractor. Avenir Rénovations is a network of experts in renovation of all trades, with a 360° approach:
- Comprehensive management of the project
- A single point of contact from start to finish
- Premium execution quality, respect for deadlines
- Clear and detailed quotes
- Ten-year guarantees and regulatory compliance
Each project is managed by an experienced Project Manager, who coordinates all participants: architects, craftsmen, design offices, and engineers.
Request your free quote for a storey addition to an accessible roof terrace
Would you like to know more or get the exact budget for your project? Avenir Rénovations Belgium offers you a free and personalized quote within 48 hours.
Whether you are in Brussels, Liège, Charleroi, Namur, or elsewhere in Belgium, our experts respond quickly to assess the feasibility of your project.
Request your quote now
A consultant will call you back within 24 hours to discuss your needs.
FAQ – Storey addition to an accessible roof terrace in Belgium
Is it possible to raise an accessible roof terrace without demolishing the entire roof?
Yes, depending on the condition of the existing structure, a storey addition can be carried out without complete demolition. A preliminary study determines the feasibility and necessary reinforcements.
Is a permit required to raise an accessible roof terrace in Belgium?
Yes, a building permit is mandatory. Our teams assist you in submitting the application to your municipality.
What is the average time frame for a storey addition to a roof terrace?
On average, it takes between 3 to 6 months, including the study phase, obtaining the permit, and carrying out the work.
Can an accessible terrace be created on the new floor?
Yes, it is possible to create a new terrace on the roof of the new floor, provided that local safety and urban planning regulations are respected.
What is the difference between an extension and a storey addition?
An extension is done horizontally, encroaching on the land, while a storey addition adds space from above, without altering the ground footprint.
