Costs of a 2 metres dormer
A 2 metres dormer is the narrowest practical size — often sufficient for a single window frame and extra light or headroom above a stairwell or desk. Because the size is small, you sometimes hear expectations that are incorrect: "Then it must be cheap." In practice, it can be disappointing, because a large part of the costs is fixed regardless of the width. On this page, we explain how the price is structured, what a quote should contain, and why prices differ significantly between suppliers.
We don't quote rates — we explain how the price is structured.
What is normally included in a quote for 2 metres?
A complete quote for a 2 metres dormer typically includes these items:
- Construction: trimmer construction, studwork and battens, any steel construction.
- Exterior: roof (EPDM, zinc, or bitumen), side cheeks, and fascia board.
- Window frame and glazing: one window frame with tilt-and-turn or fixed glazing, HR++ glazing as standard.
- Insulation: roof, side cheeks, and possibly under the dormer (Rc-waarde in accordance with the Bbl).
- Interior finishing: plasterboard, sealant and plasterwork, window sill, painting.
- Installation: crane, lifting work, demolition of the existing roof section, rubble disposal.
What is not standard: electrics (sockets, switches), sun blinds, fly screens, floor finishing, and custom exterior colour finishing. Ask every supplier for the exact same list.
What determines the price the most?
At this width, the main price factors are:
Exterior material choice
Plastic and polyester are usually the most affordable choices; wood and zinc are higher. At 2 metres, the difference in absolute money is not that bad, but in percentages it is.
Window frame and glazing
HR++ glazing is standard. Triple glazing or a wider window frame with multiple openings noticeably raises this item.
Accessibility and crane
A terraced house on the street with enough space for a mobile crane is cheaper than an intermediate house in a narrow city centre. The crane itself is a fixed cost item — which barely scales with the width.
Planning permission requirement
Front roof area, monumental neighbourhood, or conflicting aesthetic review (welstand) increases the process costs (drawings, municipal fees, possibly a structural engineer).
Why is 2 metres not much cheaper than 3 metres?
Many people expect a 2 metres dormer to cost almost half of a 4-metre dormer. That is not the case. Reason: the fixed costs (setup, design, crane, demolition, disposal, finishing) are almost identical. Only the material volume and the time for finishing scale accordingly. In practice, the difference between 2 and 3 metres is therefore often 10–20%, not 33%.
Comparing three quotes side by side
Ask every supplier for the same list of specifications:
- Exterior material (brand and type)
- Roofing (EPDM, zinc, bitumen)
- Window frame type (plastic, wood, aluminium) + brand
- Glazing (HR++ or triple glazing, gas filling, U-value)
- Insulation thickness and Rc-waarde
- Interior finishing (shell / ready to move in)
- Crane and accessibility (mentioned separately)
- Warranty periods (construction, window frame, roofing)
- VAT rate (9% or 21%, depending on the age of the home)
- Planning permission and municipal fees (included/not included)
Only then can you fairly compare two amounts side by side.
Common misconceptions
- "Narrow = cheap" — fixed costs remain.
- "Shell is always cheaper" — only if you do the plasterboard, plastering, window sill, and painting yourself.
- "Plastic is always the cheapest" — at narrow sizes, the difference with wood is small.
- "No permit = no costs" — municipal fees are dropped, drawing work sometimes is not.
Comparison table
| Item | Source of variation | Impact on total |
|---|---|---|
| Construction | Standard / steel needed | Small → medium |
| Exterior material | Plastic / wood / zinc | Medium |
| Window frame + glazing | HR++ / triple, frame type | Medium → large |
| Insulation | Rc 4,5–6,3 | Small |
| Interior finishing | Shell / complete | Medium |
| Installation and crane | Accessibility | Large (fixed) |
| Planning permission | Required / permit-free | Small → medium |
Frequently asked questions
Short, honest answers to recurring questions.
- Is a 2 metres dormer always permit-free?
- No. Permit-free status depends on the roof area (front/rear), height above the roof eaves, distance to the roof edge, and aesthetic review (welstand). Width alone is not decisive.
- How much does a 2 metres dormer cost?
- We do not mention rates. The price depends on material, window frame type, glazing, insulation, finishing, and accessibility. Three quotes with identical specs give you the fairest comparison.
- Can I save costs by ordering a shell?
- Yes, provided you install the plasterboard, plastering, window sill, painting, and possibly electrics yourself or have it done. Otherwise, the difference is small.
- Does it matter whether it is the front or rear roof?
- Yes. The front roof area is almost always subject to planning permission and sensitive to aesthetic review (welstand). That increases process costs.
- Is HR++ glazing sufficient?
- For the Rc-waarde requirements of the Besluit bouwwerken leefomgeving (Bbl), HR++ glazing is usually sufficient. Triple glazing is a gain in comfort, not an obligation.
- Does the VAT rate differ?
- The 9% rate applies to labour for homes older than 2 years. Materials are 21%. A quote must show this split.
- How long does installation take?
- A prefab dormer is installed in 1 day; interior finishing follows in 1–3 days. Traditional on-site construction takes 4–7 working days.
- Does a trimmer construction count as additional work?
- Almost always. Ask if this is included in the basic quote and if steelwork is calculated separately.
- Is scaffolding or a crane already included?
- With prefab almost always; with traditional not always. This should be explicitly specified.
- What is the impact of accessibility?
- A terraced house on a wide street costs less lifting work than an intermediate house in a narrow city centre. Ask about this explicitly.
Summary
A 2 metres dormer is technically the same intervention as a wider dormer — only the material volume is different. The fixed costs (crane, setup, demolition, disposal, finishing) remain largely the same, making the price per linear metre relatively high. Compare three quotes based on identical specifications, pay attention to the choice of window frame and glazing, and ask for accessibility and planning permission costs separately.