What is a dormer loft conversion?
A dormer loft conversion adds a box-shaped structure to the rear roof slope, creating vertical walls and full headroom across most of the new room. It is the most common loft conversion in the UK because it works on terraced, semi-detached and detached houses.
How much does a dormer loft conversion cost in Cheltenham?
In Cheltenham, a dormer loft conversion typically costs £49,000–£69,500 for a typical rear dormer with en-suite, including VAT at 20% (standard rate). Building costs in the South West are close to the UK average, so the figures for Cheltenham are close to our national guide. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A typical rear dormer with en-suite | £49,000–£69,500 |
| Higher specification | £69,500–£87,000 |
The biggest cost drivers are:
- Staircase position
- Scaffolding and access
- Fire safety upgrades to the existing house
- En-suite or bathroom
For a figure based on your own measurements, try the guide price tool, then book a free home visit for a fixed quote.
Do you need planning permission for a dormer loft conversion in Cheltenham?
The approval route for Cheltenham is set by planning law in England. In England a rear dormer is often permitted development if the extra roof volume is no more than 40 cubic metres on a terraced house or 50 on other houses, it does not face the road, sits no higher than the ridge and is set back from the eaves, with matching materials and obscure-glazed side windows. Balconies, front dormers and work in conservation areas need planning permission.
Where work involves a shared wall, building on the boundary, or digging foundations within 3 metres of a neighbour’s building and deeper than its foundations (or within 6 metres for deeper work), the Party Wall etc. Act 1996 applies and notices must be served before work starts.
At the survey we check your house’s planning history and any restrictions, and tell you which route applies.
What we handle
What we take care of:
- Drawings and structural calculations
- Building control completion certificate
- Party wall notices for shared walls
- Insulation, plastering, electrics and plumbing
- Dormer structure, roof covering and windows
- New staircase and fire-safe escape route
How long does it take?
Expect 6 to 9 weeks on site. Design and approvals come first and typically take 6 to 12 weeks, depending on the approval route.
Building in Cheltenham
In parts of the South West, protected landscapes and conservation areas shape what can be built, so materials and roof forms are chosen carefully.
Projects in Cheltenham (GL50 and GL52) are surveyed in person before we quote, so the price reflects your actual property.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 02
Design and pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 03
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about dormer loft conversions in Cheltenham
Who approves a dormer loft conversion in Cheltenham?
Planning matters in Cheltenham go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
How long does it take?
Usually 6 to 9 weeks on site.
How much does a dormer loft conversion cost in Cheltenham?
In Cheltenham, a dormer loft conversion typically costs £49,000–£69,500 for a typical rear dormer with en-suite, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.
Do I need a party wall agreement?
In England and Wales, if the conversion cuts into or builds on a shared wall, notices must be served under the Party Wall etc. Act 1996.
How much head height do I need?
Ideally at least 2.2 metres from the top of the ceiling joists to the underside of the ridge. Less can still work with a dormer, but we check this at the survey.