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 Barry?
In Barry, a dormer loft conversion typically costs £44,000–£62,500 for a typical rear dormer with en-suite, including VAT at 20% (standard rate). Building costs in Wales run about 8% below the UK average, and the figures for Barry are adjusted to reflect that. 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 |
What moves the price most:
- Staircase position
- Scaffolding and access
- En-suite or bathroom
- 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 Barry?
Before anything is built in Barry, we confirm which approvals apply in 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.
The Party Wall etc. Act 1996 applies in Wales, so notices must be served before work on a shared wall, on the boundary, or excavation close to a neighbour’s foundations.
Our first visit includes a check of your planning history, so you know the route before paying for drawings.
What we handle
Handled as part of most dormer loft conversions:
- Dormer structure, roof covering and windows
- Measured survey and head-height check
- Drawings and structural calculations
- Steel beams and new floor joists
- Insulation, plastering, electrics and plumbing
- Building control completion certificate
How long does it take?
The build itself usually takes 6 to 9 weeks on site. Before that, surveys, drawings and approvals usually take 6 to 12 weeks, longer if the council asks for changes.
Building in Barry
Wales has many terraced valley streets, stone cottages and post-war estates, so extension designs are shaped by slopes, materials and local character.
We work across Barry and neighbouring areas such as Penarth, Cardiff and Caerphilly. Postcodes we cover in Barry include CF62.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 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
Build and handover
Work follows the agreed programme, with inspections along the way and a completion certificate at the end.
Questions about dormer loft conversions in Barry
How much does a dormer loft conversion cost in Barry?
In Barry, 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.
Who approves a dormer loft conversion in Barry?
Planning matters in Barry go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
Do I need planning permission for a dormer loft conversion in Barry?
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.
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.
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 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.