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 Bolton?
In Bolton, a dormer loft conversion typically costs £45,000–£64,000 for a typical rear dormer with en-suite, including VAT at 20% (standard rate). That range is adjusted for the North West, where domestic building work typically costs around 6% below the national average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A typical rear dormer with en-suite | £45,000–£64,000 |
| Higher specification | £64,000–£80,000 |
The main things that change the cost:
- En-suite or bathroom
- Scaffolding and access
- Dormer size and roof structure
- Staircase position
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 Bolton?
Before anything is built in Bolton, we confirm which approvals apply 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.
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:
- Party wall notices for shared walls
- Insulation, plastering, electrics and plumbing
- Drawings and structural calculations
- Building control completion certificate
- New staircase and fire-safe escape route
- Steel beams and new floor joists
How long does it take?
Expect 6 to 9 weeks on site. Allow time beforehand for drawings and approvals, usually 6 to 12 weeks.
Building in Bolton
The North West has many brick terraces and inter-war semis, where kitchen extensions and dormer loft conversions add space without moving.
From BL1 outwards, we take on projects throughout Bolton and the surrounding parts of Greater Manchester.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 02
Design and fixed quote
Drawings, structural calculations and an itemised, fixed price for the agreed specification.
- 03
Permissions sorted
Applications, building control and neighbour arrangements, all before the start date.
- 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 Bolton
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.
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 does a dormer loft conversion cost in Bolton?
In Bolton, a dormer loft conversion typically costs £45,000–£64,000 for a typical rear dormer with en-suite, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.
Do you build dormer loft conversions in Bolton?
Yes. We build dormer loft conversions across Bolton, including postcodes BL1, BL11 and BL78. Every project starts with a free home visit.
How long does it take?
Usually 6 to 9 weeks on site.