Home extensions — Amsterdam, Amstelveen, Haarlem & Zaandam
Build a home extension
A bright rear extension: more kitchen, more living room and more life on the ground floor.
- extra living space
- +15–30 m²
- average construction
- 3–4 weeks
- per m² estimate
- €2,000–3,500
What an extension adds
More room on the ground floor
A rear extension changes the whole ground-floor plan: the kitchen can move towards the garden, the dining table gains daylight and the old kitchen can become a utility room or workspace. It is the most popular way to gain space without moving.
15–30 m² of extra living space
A three- to four-metre-deep extension across the width of the house can create a full kitchen-diner or a second seating area.
Daylight from three directions
Large glazed façades, rooflights and careful orientation bring daylight deep into the existing rooms.
Added property value
Extra ground-floor square metres are among the best-performing home improvements in the Randstad.
Permits & regulations
The four-metre rule, clearly explained
A rear extension is often permit-free when it stays within four metres of the original rear façade, is no higher than five metres and covers no more than half the rear plot. Local environmental plans and protected townscapes can impose additional conditions.
If your plan falls outside those limits, we prepare the drawings, structural calculations and design justification and submit the complete application through the Omgevingsloket. The standard decision period is eight weeks.
Where the Dutch Quality Assurance Act requires independent checks, we coordinate the quality assurer and provide the consumer file at handover.
Engineering
The details that make the difference
The quality of an extension is determined below the floor and at the connection to the existing house — exactly where it becomes invisible later.
Foundation matched to the soil
Piles are common on peat around Amsterdam and Zaandam; strip foundations can work on firmer ground. Our engineer decides from evidence, not an assumption in the quote.
No thermal bridges
We detail a continuous insulation line at the existing façade, with Rc 4.7 walls, Rc 6.3 roof insulation and HR++ or triple glazing.
One team through to completion
Plaster, floor, electrics, underfloor heating and kitchen connections follow one programme with one project manager.
Process
From sketch to handover
- 01
Survey & first sketch
We measure the house, discuss priorities and budget and prepare an initial direction with a cost range.
- 02
Permit check & engineering
Our engineer checks foundation and structure; we confirm permit-free status or prepare the application.
- 03
Fixed price & programme
You receive one fixed sum and a week-by-week programme including the agreed finish.
- 04
Construction in 3–4 weeks
One team builds foundation, shell, roof, glazing and interior. We open the old façade only after the extension is weatherproof.
Costs
Extension cost estimate
Foundation, glazing and finish determine the range. These are realistic 2026 figures including 21% VAT.
| Specification | Estimate (per m²) |
|---|---|
| Shell extension (foundation, structure, roof) | €2,000 – €2,500 per m² |
| Fully finished (plaster, floor, electrics) | €2,500 – €3,000 per m² |
| Turnkey incl. kitchen/plumbing connections | €3,000 – €3,500 per m² |
Estimate including 21% VAT, 2026 price level. Piles, large spans and custom glazing affect the price; after the survey you receive one fixed price.
Projects
Extensions we have built
Home extensions in Amsterdam · Amstelveen · Haarlem · Zaandam.
Frequently asked questions
What clients ask us before starting
Often, yes. A rear extension up to four metres deep can usually be permit-free when it stays within the rear plot rules, is no higher than five metres and covers no more than half the rear garden. Protected townscapes have stricter rules. We check your address free of charge and confirm the result in writing.
What would an extension to your home cost?
Book a free consultation. We will review the options, the permit situation and an initial cost estimate — with no obligation and a reply within one working day.
contact@renovaco.nlKvK 92576907