Design your extension.
About the prices and your design
Your estimate uses 78 checked size prices and public option prices. Intermediate sizes are calculated, retaining the price increase above 7.5 metres wide. Green roofs and underfloor heating are calculated for two modules on wide extensions.
All selected options, a plastering estimate if selected and an adjustable transport allowance are included with VAT. The estimate is not a binding quotation. Work outside the described scope is excluded.
The model shows dimensions and choices schematically. It is not an exact product rendering, installation drawing or structural design.
My design — Prefab Aanbouw
Price estimate · 13 September 2026 · including VAT · not a quotation
Total estimated price
€41,450Including VAT, selected options and transport allowance- Base design
- €39,950
- Transport (allowance)Calculation assumption
- €1,500
How your price is calculated
The base price for this size was checked against the public reference.
Plastering uses the estimated area of new walls and ceilings at €25/m². The transport budget is an adjustable allowance, not a confirmed haulage rate.
Outside this estimate
- Permits, surveys and additional work on the existing home
- Kitchen, floor finishes, furniture and landscaping
De Prefabriek public configurator Prices checked: 13 September 2026.Prefabaanbouw.nl estimate using public reference prices and our own calculation assumptions. A final quotation follows an assessment of your home.
All design choices
- Pricing basis
- Estimate with checked references and calculation assumptions
- Reference date
- 2026-09-13
- External dimensions
- 4.5 × 2 m
- External floor area
- 9 m²
- Facade cladding
- Red brick
- Frames & glass
- French doors · white (uPVC)
- Rooflight
- No rooflight
- Green roof
- No green roof
- Roof trim
- Aluminium roof trim
- Overhang
- No overhang
- Outside light
- No outdoor light
- Outdoor socket
- No outdoor socket
- Outside tap
- No outdoor tap
- Downpipe
- PVC · left
- Plastering
- No plaster finish; boards remain visible
- Radiators
- No radiator
- Underfloor heating
- No underfloor heating
- Ceiling light connections
- None
- Recessed spotlights
- None
- Wall light connections
- None
- Sockets
- None
- Spotlight controls
- Switched · left
- Brick soldier course
- No
- Rooflight shading
- No
- Rear access
- Yes
- Existing wall opening
- No
- Transport (allowance)
- €1,500