Extension cost with a roof lantern: a rough guide

Extension cost: a cautious indication

What an extension costs depends on many choices: size, foundations, wall finish, frames, floor and services. The market often quotes roughly €1,500 to €3,000 per m² of floor area for a complete extension. For an extension of 3 by 4 metres, that puts you roughly between €18,000 and €36,000.

Take those figures with a large pinch of salt. A simple prefab extension sits at the lower end, while an extension with lots of glass, underfloor heating and a new kitchen sits at the top or above. Always get several quotes from builders in your area.

What a roof lantern adds to your extension

An extension makes the house deeper. As a result, the middle of the home often gets less daylight. A roof lantern on the extension brings light back where it is needed: at the transition between the old and new parts.

For most extensions, people choose a mono-pitch roof lantern. It starts from €1,532. For more on the price factors, read how much a mono-pitch roof lantern costs.

• Daylight in the middle of the home
• View of the sky from kitchen or living room
• Mono-pitch from €1,532, made to measure
• HR++ as standard, triple as an option

Costs around the roof lantern in the extension

Besides the roof lantern itself, the opening in the roof requires work from your builder. The joists are trimmed, an insulated upstand is built and the roof covering is connected. Inside, the reveals are finished. Include that work in your builder's quote so it does not come back as extra work. An indication of the installation work is under having a roof lantern installed.

If you are considering a fully glazed roof instead of a roof lantern, read roof lantern or glass roof. A roof lantern keeps part of the roof closed and insulated, which helps against overheating.

Permission and planning

The roof lantern itself usually does not need separate planning permission. The extension sometimes does, depending on size, location and the zoning plan. Read planning permission for a roof lantern and check with your municipality. Our lead time is from 2 weeks after approval, so the roof lantern usually fits your builder's schedule well.

Frequently asked questions