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Dormer cost · Detail

5 metre dormer cost

A 5 metre dormer is one of the largest standard sizes. It adds significant space but also brings the biggest structural and access considerations.
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Short answer

A 5 metre dormer in the UK typically costs between £12,000 and £22,000 installed. The wider span means more materials, more structural work and often a heavier crane lift.

Price range

  • Budget — £12,000–£15,000 with basic PVC and minimal interior finish.
  • Mid-range — £15,000–£19,000 with good insulation, HR++ glazing and solid finish.
  • Premium — £19,000–£26,000+ with timber or composite, triple glazing, high-end finish and full permit handling.

Price drivers

Structural and access

A 5 metre dormer is a serious load. The company should explain the structural connection and the crane plan clearly before you sign.

The full checklist

Checklist

5 metre dormer quote checklist

  1. 01Width is specified as 5 metres internally and externally.
  2. 02Structural reinforcement is described in the quote.
  3. 03Crane capacity and access are confirmed.
  4. 04Material, frame and glazing are named.
  5. 05Insulation level is stated as a number.
  6. 06Permit handling and fees are covered.
  7. 07Interior finish level is clear.
  8. 08Warranty terms are attached.

FAQ

FAQ

Veelgestelde vragen

01What does a 5 metre dormer cost?
In the UK a 5 metre dormer typically ranges from £12,000 to £22,000 or more. The wide span increases materials, structural work and often the size of the crane needed.
02Is a 5 metre dormer much more expensive than a 4 metre one?
Yes. The extra metre adds cladding, roof covering, glass, structural work and labour. The fixed costs are similar, but the variable costs scale with width.
03Do I need planning permission for a 5 metre dormer?
Very likely, especially if it is on the front or in a conservation area. Always check with your local planning authority before budgeting.
04Can a 5 metre dormer be prefab?
Yes, but the unit is much larger and heavier. The crane and access planning are more critical than for smaller sizes.
Conclusie
A 5 metre dormer is a big investment in space and budget. The extra width magnifies every cost driver, so itemised quotes and clear structural planning are essential.