Dormer cost and price differences
Why one dormer costs €8,000 and another €18,000, even when they look almost the same. The items that explain the gap, and how to read a quote properly.
Short answer
What drives a dormer price?
The price of a dormer is the sum of materials, insulation, glazing, frames, finishing, lead and flashing, transport, crane work, permit handling and labour. Each of these items can be chosen at very different quality levels — and that is exactly where price differences come from.
The price drivers
What you are actually paying for
| Item | Low cost | Higher cost | Why it matters |
|---|---|---|---|
| Material | Basic PVC | Composite, timber, HPL | Look, lifespan and finish quality |
| Insulation | Standard pack, R≈3.5 | R≥4.5 with no thermal bridges | Comfort and energy bill |
| Glazing | HR++ double | Triple, sound-reducing | Heat, comfort and noise |
| Frames | Standard PVC | Aluminium-clad or hardwood | Lifespan and appearance |
| Finish inside | Basic plasterboard | Painted, with mouldings | How 'finished' the room feels |
| Lead / flashing | Standard rolled lead | Code 5 lead or alternatives | Watertightness over time |
| Permit | Homeowner does it | Company handles it end-to-end | Time, risk and rejection risk |
| Crane / transport | Sometimes excluded | Included in the quote | Surprises on invoice day |
Watch out
Common hidden costs
Practical
Quick checklist for a fair comparison
Checklist
Run every quote past these
- 01All materials named by brand or grade.
- 02R-value of the full insulation package stated.
- 03Glazing type and frame material listed.
- 04Lead and flashing work included on paper.
- 05Permit handling spelled out, with cost.
- 06Crane and transport included or named.
- 07Interior finish level described.
- 08Lead time and install duration stated.
- 09Payment schedule split over milestones.
- 10Warranty terms attached as a document.
Read next
Related guides
Guide
Choosing a dormer company
The checks that separate solid companies from cheap quotes.
Lees verderGuide
Dormer permits and planning rules
Permit-free, permit needed, aesthetics — how the rules work.
Lees verderGuide
Types of dormers
Prefab, traditional, flat-roof and pitched-roof options compared.
Lees verderQuick answers
Frequently asked questions
FAQ
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01What does a dormer cost on average?
Most dormers fall in a wide range from about €7,000 to €20,000 or more, depending on width, material, insulation, finish, planning rules and the complexity of the roof. A single average number is rarely useful — always ask for a written breakdown.
02Why is one quote thousands of euros higher than another?
Usually it is a different insulation package, different frames or glazing, more finishing work, included permit handling, or a more experienced crew. Compare per line item, not on total price.
03Is a prefab dormer cheaper than a traditional one?
Often yes, because prefab is faster to install. But the price difference is smaller than people think once you add insulation, finish and crane work to a fair comparison.
04What hidden costs should I watch for?
Crane and street permits, lead and flashing work, interior plastering, shutters, electrical work and disposal of old materials are the most common items that quietly add to the bill.
Conclusie
The price of a dormer is not one number — it is the sum of many choices. Once you compare quotes per item instead of per total, the differences start to make sense, and so does your decision.