Yes. A ridge raising plus a dormer or large skylight is common — the ridge raising creates the volume, the dormer/skylight provides daylight and frontal headroom.

Is a dormer really much cheaper?

Absolutely in total amount, but per m² gained they are close to each other. The difference is in how much space you get.

What does aesthetic review (welstand) do for both?

For a dormer, aesthetic review mainly looks at proportion, material and placement. For ridge raising, at the streetscape as a whole — do your rooflines still match the neighbours?

What gives the most increase in value?

Ridge raising — more m² of living space counts more heavily in the WOZ (property valuation) and appraisal than a local extension.

Can I upgrade from a dormer to a ridge raising later?

Technically yes, but you pay demolition and construction costs twice. Better to make the right choice the first time.

What if I have a terraced house with a low ridge?

Classic ridge raising candidate. Almost always, ridge raising yields more return here than a dormer.

And if I just want more light?

Then a dormer or even just a large Velux skylight is often enough — no ridge raising needed.

Ridge Raising · Basis·8 min read

Ridge raising or dormer — what suits your loft?

Two questions every homeowner asks themselves before tackling the loft: 'Is a large dormer enough?' or 'Should the ridge be raised?'. The answer depends on what you want to achieve, how much you want to invest and what aesthetic review (welstand) allows. We compare both interventions objectively side by side.

General explanation — no structural advice. Always consult a structural engineer.

What do you achieve with each intervention?

A dormer creates a straight extension in one place on the roof. This creates local headroom (approx. 2,3 m) and daylight. The rest of the loft remains as it is — with the existing sloping walls.

A ridge raising lifts the entire roof structure or straightens it. The result is a loft with headroom over (almost) the entire floor area, comparable to a standard floor.

Ask yourself the question: do you need one room with good light, or do you want a fully-fledged extra floor?

Costs compared

Indicative total costs in 2026 (including VAT, excluding finishing):

Dormer 3 m, prefab: € 8.500 – € 12.500
Dormer 5–6 m, custom-made: € 13.000 – € 20.000
Straight ridge raising terraced house: € 25.000 – € 40.000
Full ridge raising wide house: € 40.000 – € 60.000

Per m² gained space, the amounts are surprisingly close to each other (€ 1.500–2.500/m²). The difference lies in the total volume you add.

Planning permission and aesthetic review

Here the difference sharply diverges:

A dormer on the rear roof plane is often permit-free — provided it is within the dimensions of the Bbl (Dutch Building Decree). See Permit-free.
A ridge raising almost always requires planning permission and is assessed by aesthetic review (welstand) on the streetscape.
In 1930s neighbourhoods and streets with continuous rooflines, aesthetic review is stricter about ridge raising than about a neat dormer at the rear.
A dormer at the front or ridge raising in a protected cityscape: both are often a no.

Lead time and inconvenience

Prefab dormer: 1 day placement, 1–2 days finishing. House remains habitable.
Custom-made dormer: 3–5 working days.
Ridge raising: 4–8 weeks, of which a few days with a temporary roof (rain and dust risk).

For families with young children or those working from home, that difference in lead time is often decisive.

Decision tree — which one suits you?

Go through these questions in order:

1. How many rooms do you want to add? One → dormer. Two or more → ridge raising. 2. What is your budget? < € 20.000 → dormer. > € 25.000 → ridge raising possible. 3. How high is your current ridge? > 2,8 m internally → dormer is often sufficient. < 2,5 m → ridge raising yields much more. 4. What does aesthetic review (welstand) say in your street? Continuous roofline → dormer at the rear is safer. Neighbours already raised → ridge raising goes through faster. 5. How long will you continue to live there? < 5 years → dormer. > 7 years → ridge raising pays for itself.

Overview

Aspect	Dormer	Ridge raising
Space gain	5–10 m² locally	10–20 m² across entire loft
Costs	€ 8.500 – € 20.000	€ 25.000 – € 60.000
Lead time	1–5 days	4–8 weeks
Planning permission	Rear often permit-free; front almost always required	Almost always required
Aesthetic review	Mild at rear, strict at front	Strict — assesses streetscape
Habitable during work	Yes	Partially — loft closed off, rain risk
Best choice for	One extra room or more daylight	Two+ rooms, low current ridge

Dormer vs ridge raising — direct comparison

Frequently asked questions

Short, honest answers to frequently asked questions.

Can I combine both?: Yes. A ridge raising plus a dormer or large skylight is common — the ridge raising creates the volume, the dormer/skylight provides daylight and frontal headroom.
Is a dormer really much cheaper?: Absolutely in total amount, but per m² gained they are close to each other. The difference is in how much space you get.
What does aesthetic review (welstand) do for both?: For a dormer, aesthetic review mainly looks at proportion, material and placement. For ridge raising, at the streetscape as a whole — do your rooflines still match the neighbours?
What gives the most increase in value?: Ridge raising — more m² of living space counts more heavily in the WOZ (property valuation) and appraisal than a local extension.
Can I upgrade from a dormer to a ridge raising later?: Technically yes, but you pay demolition and construction costs twice. Better to make the right choice the first time.
What if I have a terraced house with a low ridge?: Classic ridge raising candidate. Almost always, ridge raising yields more return here than a dormer.
And if I just want more light?: Then a dormer or even just a large Velux skylight is often enough — no ridge raising needed.

Summary

A dormer and a ridge raising solve different problems. If you want one extra room with daylight, a dormer is faster, cheaper and often permit-free. If you want to use your entire loft as a fully-fledged floor, then a ridge raising — more expensive and more invasive — is the right investment. Combining is allowed and common.

Read further in our comprehensive guides

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