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Roof extension cost varies widely.
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Roof extension cost varies widely. According to common market indications, a complete roof extension costs roughly €25,000 to €60,000, depending on size, prefab or traditional build and finish. That is an indication, not our price. A roof lantern on or against the extension comes on top, for example a wall-abutting lean-to from €1,689.
A roof extension turns a flat roof into an extra storey. Costs vary widely. The market quotes roughly €25,000 to €60,000 for a complete extension. A small prefab unit sits at the lower end, while a spacious extension with a bathroom and lots of glass sits at the top or above.
Structural changes, stairs, services and finish together determine the amount. Use this range only as an initial orientation and always ask a builder or roof extension specialist for a quote.
On a roof extension with a roof lantern, two situations are common. The extension meets a taller wall of the neighbours or of your own house. Then a wall-abutting lean-to is logical: light from above and the side, with a flashing profile per wall type. The starting price is €1,689.
Or the roof lantern goes into the flat roof of the extension itself, for example above a stairwell or a bathroom. Then a mono-pitch roof lantern fits. A roof lantern above the stairs brings light deep into the floor below.
A roof extension is often a sleeping floor. Under a roof, a room warms up quickly, and at night you want it cool and quiet. For a bedroom we tend to recommend triple glazing, with a U-value of about 0.5 W/m²K and around 36 dB sound reduction. Also read overheating under a roof lantern.
In addition, the roof lantern has to be lifted to height. That often requires a crane or aerial platform and good scheduling with the builder. A lead time from 2 weeks helps get the roof lantern on site at the right moment.
A roof extension often requires planning permission, especially if it is visible from the street. The roof lantern itself usually does not need separate permission. Read planning permission for a roof lantern and contact your municipality in good time, so your schedule does not stall.
According to common market indications, roughly €25,000 to €60,000 for a complete extension. Size, structure, prefab or traditional build and finish make the big difference. Always ask a builder for a quote.
If the extension meets a taller wall, a wall-abutting lean-to is often best. If you want light in the roof of the extension itself, a mono-pitch roof lantern fits. We are happy to think along in special situations.
Not always. Above a bedroom or with a north or west orientation, triple glazing is a good choice. For a study or playroom facing south, HR++ is often more than enough.
Send a photo or sketch with dimensions. Within 24 hours you receive a quote with glazing options, lead time and price.
Request a quote Get in touchA few questions, a photo or the dimensions, and we will prepare a tailored quote. Prefer to call: +31 342 223 190.
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