Costs
What does more space cost?
Transparent figures from the start. Calculate your own estimate using the ranges we quote in 2026. All amounts include 21% VAT.
Estimate incl. 21% VAT
€ 57,500 to € 72,500
Estimate at 2026 price levels. The actual price depends on structure, soil and design details; after a survey you receive one fixed price.
Need an exact price? Request a quoteCost breakdown
Where the budget goes
Three categories determine most of the price and can be assessed in advance.
Structure & foundation
Piles or strip foundations, steel frames and structural calculations. On peat soil the foundation can represent 15–20% of the budget.
Envelope & glazing
Façade, roof and glazing determine both comfort and appearance. Current insulation standards are our baseline.
Interior & services
Plaster, flooring, heating, electrics and plumbing create the largest spread between shell and turnkey.
Estimate by service
The figures at a glance
Extension
| 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.
Roof extension
| Specification | Estimate (per project) |
|---|---|
| Shell roof extension on a terraced house | €45,000 – €70,000 |
| Fully finished, including staircase | €70,000 – €95,000 |
| Turnkey, including bathroom | €95,000 – €120,000 |
Estimate including 21% VAT, 2026 price level. The existing structure and roof type determine the range; our engineer checks this in advance.
Dormer
| Specification | Estimate (per dormer) |
|---|---|
| Standard-width rear dormer | €8,000 – €12,000 |
| Wide or front dormer (with permit) | €12,000 – €16,000 |
| Custom build incl. attic interior | €16,000 – €20,000 |
Estimate including 21% VAT, 2026 price level. Width, material and finish determine the final price.
Good to know
All figures include 21% VAT at 2026 prices. Home improvements are often financed through a construction account or mortgage increase; a local adviser can assess this.
Our fixed price covers every item listed in the quote. Additional work happens only after your written approval, never as a surprise on the final invoice.
Prefer an exact price to an estimate?
After one site survey you receive a fixed price broken down by item, with no obligation and normally within a week.
contact@renovaco.nlKvK 92576907