House Extensions in Amsterdam and Amstelveen More room, without moving house

What we build

• Rear extension (uitbouw): the ground floor extended into the garden, most often for a larger kitchen and living room with glass doors to the garden.
• Side extension (aanbouw): an extra room beside the house, such as a study, a utility room or a ground-floor bedroom.
• Extra storey (opbouw): a new floor on a flat roof, for a bedroom or a bathroom where the attic is too low.
• The connection to the house: the old rear wall opened on a steel beam, the floor levels matched and one continuous floor with underfloor heating through the old and the new part.

Extensions we have built

• Amstelveen, August-September 2024: a single-storey rear extension with a roof light. The opening in the old rear wall rests on a steel post and beam; inside came OSB walls, a vapour membrane, plastered walls, garden doors with stained-glass toplights and an engineered wood floor.
• Amstelveen, February-April 2026: a new entrance extension at the front of a house, built against the brick facade - hardwood frames, an insulated timber-frame wall, a flat roof on joists with OSB and a roof window, and a new front door.

From first visit to handover

• Visit and measurements. We look at the garden, the rear facade, the access for materials and the neighbours, and check the rules for your address.
• Drawings and structural calculation. If a permit is needed we prepare and file the application; the municipality decides within 8 weeks and can extend that once by up to 6 weeks.
• Foundation. On Amsterdam and Amstelveen clay and peat the new part almost always stands on piles. Next to neighbouring houses, vibration-free screw piles are the usual choice.
• Shell. Floor, walls, roof and insulation go up while the house stays closed; only then is the old rear wall opened.
• Glazing and installations. Sliding or folding glass doors, roof lights, electrics, heating and drains for a kitchen in the new part.
• Finishing. Plastering, the floor with underfloor heating, the kitchen and built-in furniture, so the extension feels like part of the house and not an add-on.

Do you need a permit?

Many single-storey extensions at the back of a house need no permit. The national rules allow it when the extension stands in the back garden, more than 1 m from public space, no higher than 5 m, with living space only on the ground floor and no roof terrace. Within 4 m of the original rear facade it may rise up to 30 cm above the level of the first floor; deeper than 4 m it may only serve a secondary use, such as storage.

A permit is always needed for a listed building, for an extension at the front or on a side that faces the street, and for an extra storey. In a protected cityscape, which covers the centre of Amsterdam, only an extension at the back that does not face public space can be permit-free. The local omgevingsplan can also set a lower maximum for how much of the plot may be built on. That is why we check your address before anything is drawn.

What an extension costs

A finished rear extension of 10-20 m² costs about €45,000-€65,000 in the Netherlands, or €2,200-€3,800 per m² on average, according to Trustoo and Homedeal (2026). Small extensions cost more per m², because the foundation, the connection to the house and the glazing are needed whatever the size. If a permit is needed, Amsterdam's fees come to €2,800 for €100,000 of building costs. The full breakdown, with piles, permits and extra storeys, is in our guide to extension costs. Your own price follows a free visit, as a written quote.

One team for the extension and what goes in it

An extension is rarely only about square metres. Most clients want a new kitchen, large glass doors and a warm floor in the same project. We build all three ourselves: kitchens, windows and doors including lift-and-slide doors, and floors with underfloor heating. You deal with one site manager instead of a builder, a kitchen company and a window fitter who each blame the other.

Planning an extension? Ask for a free visit - we reply within one working day.