Frequently asked questions

It depends on the façade and on what you are changing. It is the most misunderstood question in the trade, and getting it wrong is expensive.

On a front façade, visible from public space, the rule is strict: the exemption applies only to a like-for-like replacement — same material, same shapes, same visible divisions, same colour, same profiles and widths. Replacing white wooden frames with white PVC of identical shape requires permission, because the material changes.

On a rear façade, not visible from public space, you are far freer: creating, removing or modifying openings is possible without permission, provided the property is neither listed nor in a protection zone, and the work does not affect stability.

For a listed property or one in a protection zone, permission is required in every case.

We look at this with you during the measuring visit and tell you honestly whether permission is needed. But the decision rests with your municipality: confirm with its planning department.

It depends on the number of windows, access and the state of the masonry. One window is removed and fitted in a few hours; a whole house generally takes several days.

The exact lead time is written on the quote, after the measuring visit. We don’t give a duration over the phone without having seen the site: that would be an invented figure.

About two metres in front of each opening needs to be clear, and fragile items put away. The rest we protect: dust sheets on furniture and floor, extraction while cutting.

The site is handed over clean. Removal of the old frames is included — you are not left with old profiles in the garden.

PVC offers the best insulation-to-price ratio and needs no maintenance. It is the most common choice in renovation.

Aluminium allows very slim profiles and therefore more glass for the same opening. It suits large glazed bays and contemporary façades, and costs more.

Wood remains the warmest looking and, on a listed or protected front façade, is often the only permitted material. It needs periodic maintenance.

In practice, planning constraints shape the choice as much as taste does. We discuss it on site, with the façade in front of us.

Triple glazing insulates better thermally, but it is heavier and does not always improve acoustics: against street noise, asymmetric double glazing often outperforms standard triple.

The right choice depends on orientation, noise exposure and the state of the rest of the building envelope. Triple glazing in an otherwise uninsulated house simply moves the problem.

Yes. The foams and sealants used are designed for application at low temperature, and an opening is never left open longer than the fitting takes.

We avoid days of driving rain or hard frost, for the quality of the seals. Winter is often the most available period.

We remove them and take them to sorting facilities. That is included in the price, not charged as an extra.

French, Dutch, English, Romanian, Bulgarian and German. You speak to someone who understands you, from the first call to handover.

Yes. Our base is Brussels and its outskirts — that is where we work every week. Elsewhere in Belgium we come depending on the project and volume: call us and we will tell you honestly whether the trip makes sense for you.

Two separate guarantees, and it is worth knowing which covers what.

The fitting is guaranteed for one year by us: sealing of the joint, adjustments, finishing. That is the part we answer for directly — one call is enough.

The window itself is covered by its manufacturer, and the length depends on the system: with Reynaers, for instance, the system guarantee runs ten years on the profile and the coating and five years on the hardware. That guarantee never applies directly: it goes through the professional who fitted the window, so through us. You receive the manufacturer’s documents with the invoice.

On top of that comes the two-year legal guarantee on consumer goods under Belgian law. For your specific project, ask us for the detail in writing: we would rather say it before the order than after.

The visit and measuring are free and without obligation. You receive a written quote detailing materials, glazing, lead times and finishing.

The figure on the quote is the figure on the invoice. Any extra work is agreed with you before it happens.

Rénolution grants have been scrapped for work invoiced in 2025 and 2026. But four mechanisms remain open, including 6% VAT, which saves more than the grant ever did.

We have set out the situation on a dedicated page, kept up to date.