Storey addition in Woluwe-Saint-Lambert

Our Roof Raise Services

–  Complete and detailed structural and urban feasibility study

–  Partial or complete raising of one or more roof slopes

–  Creation of an additional fully habitable floor

–  Complete overhaul of the framework and reinforcement of existing load-bearing walls

–  Complete insulation and interior finishes of the new volume created

–  Complete coordination of urban planning permit procedures

What configurations of height increase are possible?

The type of height increase considered depends on the existing structure, the dimensions allowed by the municipality, and the final use project of the new space.

Complete volume increase

The entire roof is removed and then rebuilt to a higher height, allowing for the creation of a full floor with a comfortable ceiling height across the entire available area.

Partial height increase

Only a part of the volume is elevated, a solution that limits the extent of the work while creating a targeted additional space, such as a master suite or an independent office.

VAT, permits, and assistance for a roof height increase in Brussels

The VAT at 6% applies to this type of work in a dwelling over 10 years old, subject to the usual conditions related to the registered contractor and detailed invoicing.

A building permit is systematically required for a roof height increase, as this process permanently modifies the dimensions of the building. Regarding financing, the Renolution grants remain suspended for invoices from 2025 and 2026, a decision confirmed by the Brussels government in February 2026. The ECORENO loan, relaunched in early 2026 by the Housing Fund at a reduced rate, can be mobilized for the part of the project related to insulation and the energy performance of the new volume created, which alleviates part of the overall budget.

Why choose Avenir Rénovations for your roof height increase?

A serious structural study before any commitment

We never initiate a final estimate without prior validation of the technical feasibility by an engineer, which avoids unpleasant surprises once the construction site has started and is committed.

Comprehensive support for administrative procedures

Preparation of the permit application, plans compliant with municipal requirements, monitoring of the instruction: we manage the entire administrative aspect of the project on your behalf, from start to finish.

A coordinated construction site from structural work to finishing touches

A single team follows the project from the roof removal to the interior finishes, which avoids the frequent responsibility gaps between several independent and poorly coordinated trades.

Structural feasibility and administrative procedures

Not all houses can support a height increase: this directly depends on the load-bearing capacity of the existing foundations and walls, which is precisely the subject of the prior structural study, essential before any commitment to this type of ambitious project. A consultation with the neighbors may also be requested as part of the building permit instruction, especially in case of impact on party walls or views, a process we fully support if necessary. The additional height obtained depends on the dimensions allowed by the municipality and the chosen project, but a complete floor generally requires a minimum clear height of 2.50 meters under the ceiling, plus the thickness of the new load-bearing structure and the final roof.

Construction process and comfort during work

Generally, expect three to six months between obtaining the permit and the final reception of the site, depending on the scale of the project and the complexity of the existing structure to be fully renovated. It is possible to continue living in the house during the work depending on the extent of the site and the exact timing of the roof removal: temporary protections are systematically organized to limit the impact on the rest of the occupied housing. The existing staircase can, depending on the configuration, be extended to the new level or completely redesigned if its current location does not lend itself to it, a question studied from the initial design phase. In terms of energy performance, a storey addition does not necessarily increase the bill if the insulation of the new volume meets current PEB standards; a well-insulated new level can even improve the overall performance of the housing compared to an old poorly insulated roof it replaces.

Gain a floor without leaving your neighborhood

A well-executed roof extension permanently transforms the use of a house, in Roodebeek as in other neighborhoods of Woluwe-Saint-Lambert. Given the urban planning permit timelines, it is better to start the feasibility study several months before the desired work period, without rushing.

Also discover our villa renovation projects for a complete and coherent fit-out of your home.