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 West Glamorgan?
In West Glamorgan, a dormer loft conversion typically costs £44,000–£62,500 for a typical rear dormer with en-suite, including VAT at 20% (standard rate). We start from a UK-wide guide and adjust it for Wales, where labour and materials are typically about 8% below average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A typical rear dormer with en-suite | £44,000–£62,500 |
| Higher specification | £62,500–£78,000 |
The main things that change the cost:
- En-suite or bathroom
- Scaffolding and access
- Staircase position
- Dormer size and roof structure
A guide range is only a starting point: the guide price tool gives an instant figure for your size, and a free survey turns it into a fixed quote.
Do you need planning permission for a dormer loft conversion in West Glamorgan?
Approvals for a dormer loft conversion in West Glamorgan follow the rules for Wales. In Wales roof enlargements such as rear dormers can be permitted development within volume limits and design conditions. Dormers facing a road, balconies and conservation-area work need permission.
Building regulations in Wales are set by the Welsh Government. Approval comes from the council’s building control service or a registered building control approver, with inspections during the work and a completion certificate at the end.
We check this for your address before design work starts, so there are no surprises later.
What we handle
From survey to sign-off, the job normally involves:
- Measured survey and head-height check
- Dormer structure, roof covering and windows
- Building control completion certificate
- Party wall notices for shared walls
- New staircase and fire-safe escape route
- Steel beams and new floor joists
How long does it take?
The build itself usually takes 6 to 9 weeks on site. Allow time beforehand for drawings and approvals, usually 6 to 12 weeks.
Building in West Glamorgan
Wales has many terraced valley streets, stone cottages and post-war estates, so extension designs are shaped by slopes, materials and local character.
Towns we cover in West Glamorgan include Swansea, Neath, Gorseinon and Clydach.
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
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 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 West Glamorgan
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.
Do I need planning permission for a dormer loft conversion in West Glamorgan?
In Wales roof enlargements such as rear dormers can be permitted development within volume limits and design conditions. Dormers facing a road, balconies and conservation-area work need permission.
What fire safety is required?
Building regulations require a safe escape route. Converting a two-storey house to three storeys usually means a protected stairway with fire doors to habitable rooms and mains-wired smoke alarms.
How much does a dormer loft conversion cost in West Glamorgan?
In West Glamorgan, a dormer loft conversion typically costs £44,000–£62,500 for a typical rear dormer with en-suite, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.
How long does a dormer loft conversion take in West Glamorgan?
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.