Covering Horley
Our coverage around Horley (RH6) also includes Crawley, Redhill and Reigate.
Homes in the South East
The South East has a lot of 1930s and post-war semi-detached housing, well suited to rear extensions and hip-to-gable loft conversions, alongside period properties in conservation areas that need a more careful design.
What is a dormer loft conversion?
A dormer loft conversion builds a box-shaped extension out from the rear slope of the roof, creating vertical walls and full head height across most of the new floor. It is the most popular type of loft conversion because it gives the most usable space for the cost.
- Volume calculation and permitted development check
- Dormer frame, roof covering and cladding
- Staircase, insulation and plasterboard
How much does a dormer loft conversion cost in Horley?
Indicative costs for dormer loft conversions. London and the South East usually sit towards the top of each range.
| Dormer loft conversions | Guide price incl. VAT |
|---|---|
| Rear dormer, bedroom only | £50,000 to £65,000 |
| Full-width dormer with en-suite | £60,000 to £80,000 |
| L-shaped dormer (over rear outrigger) | £65,000 to £90,000 |
What approvals does a dormer loft conversion need in England?
Projects in England go through two separate checks. Planning (or confirmation that the work is permitted development) comes from the district, borough or unitary council, and building regulations approval comes from the council’s building control team or a registered building control approver. Where work touches a shared wall or digs near a neighbour’s foundations, the Party Wall etc. Act 1996 applies.
In England many loft conversions are permitted development: the extra roof volume must stay within 40 m³ on a terraced house or 50 m³ on a semi or detached house, nothing can sit higher than the existing ridge, no dormer can face a road on the main elevation, and side windows must be obscure-glazed and non-opening below 1.7 m.
What should I think about before starting?
- Dormers on the front of the house facing a road are not permitted development in England.
- Dormer cheeks close to a shared wall can trigger the Party Wall Act.
What happens after I enquire?
- Tell us about the project. Call, use the guide price tool or send the form with a few photos and a postcode.
- Free site visit. We measure up, look at access, drains and the structure, and talk through options and budget.
- Drawings, approvals, written quote. We prepare the design, apply for the approvals it needs, and give you a fixed price in writing.
- We build it. Work follows an agreed programme, with inspections at each stage and a final sign-off.
Questions about a dormer loft conversion in Horley
Is a dormer permitted development?
Rear dormers in England often are, within the 40 m³ (terrace) or 50 m³ (semi or detached) volume allowance. Front dormers facing a road are not.
How long does a dormer conversion take?
Around 8 to 12 weeks on site.
Can you visit a house in Horley to quote?
Yes. After a short call we arrange a site visit to measure up and agree what the design needs to do, then send a written price.
Other towns nearby
- Dormer loft conversions in Crawley
- Dormer loft conversions in Redhill
- Dormer loft conversions in Reigate
- Dormer loft conversions in East Grinstead
Learn more about dormer loft conversions, or see every project we cover in Horley.

