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 Worthing?
In Worthing, a dormer loft conversion typically costs £54,000–£76,000 for a typical rear dormer with en-suite, including VAT at 20% (standard rate). That range is adjusted for the South East, where domestic building work typically costs around 12% above the national average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A typical rear dormer with en-suite | £54,000–£76,000 |
| Higher specification | £76,000–£95,000 |
The biggest cost drivers are:
- Dormer size and roof structure
- Staircase position
- Scaffolding and access
- En-suite or bathroom
Your exact price depends on the survey and drawings. The guide price tool gives a quick range in the meantime.
Do you need planning permission for a dormer loft conversion in Worthing?
The approval route for Worthing 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
From survey to sign-off, the job normally involves:
- Party wall notices for shared walls
- Measured survey and head-height check
- New staircase and fire-safe escape route
- Drawings and structural calculations
- Insulation, plastering, electrics and plumbing
- Dormer structure, roof covering and windows
How long does it take?
Build time is typically 6 to 9 weeks on site. Allow time beforehand for drawings and approvals, usually 6 to 12 weeks.
Building in Worthing
The South East has a broad mix of housing, from Victorian terraces in the towns to post-war semis and newer estates, so extension types vary street by street.
Our Worthing coverage includes postcode districts BN11, BN91 and BN99, and we also work in nearby places such as Lancing, Shoreham-by-Sea and Portslade.
How it works
- 01
Free visit
We look at the property, talk through what you want and measure up. There is no charge and no obligation.
- 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
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about dormer loft conversions in Worthing
Will I need to move out?
No. Most of the work is done from scaffolding and the roof. The new staircase is formed near the end, which causes a few days of disruption.
Does a dormer loft conversion need planning permission?
A rear dormer is often permitted development in England, provided the extra roof volume is within 40 cubic metres on a terraced house or 50 on a semi-detached or detached house, and it does not face the road. Front dormers and houses in conservation areas usually need an application.
How long does a dormer loft conversion take in Worthing?
Typically 6 to 9 weeks on site. Design and approvals beforehand usually take 6 to 12 weeks.
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.
How much does a dormer loft conversion cost in Worthing?
In Worthing, a dormer loft conversion typically costs £54,000–£76,000 for a typical rear dormer with en-suite, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.