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 Grantham?
In Grantham, a dormer loft conversion typically costs £45,500–£64,500 for a typical rear dormer with en-suite, including VAT at 20% (standard rate). The guide for Grantham reflects typical costs in the East Midlands, roughly 5% below the UK-wide figure. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A typical rear dormer with en-suite | £45,500–£64,500 |
| Higher specification | £64,500–£80,500 |
What moves the price most:
- Fire safety upgrades to the existing house
- Dormer size and roof structure
- En-suite or bathroom
- Scaffolding and access
For a figure based on your own measurements, try the guide price tool, then book a free home visit for a fixed quote.
Do you need planning permission for a dormer loft conversion in Grantham?
Approvals for a dormer loft conversion in Grantham follow the rules for 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
The work we manage on a dormer loft conversion:
- Insulation, plastering, electrics and plumbing
- Drawings and structural calculations
- Party wall notices for shared walls
- Steel beams and new floor joists
- Building control completion certificate
- Measured survey and head-height check
How long does it take?
Expect 6 to 9 weeks on site. Design and approvals come first and typically take 6 to 12 weeks, depending on the approval route.
Building in Grantham
In the East Midlands, many estates built since the 1960s have integral garages that convert well into a study or bedroom.
Our Grantham coverage includes postcode districts NG31, and we also work in nearby places such as Newark on Trent, Melton Mowbray and Oakham.
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
Planning or permitted development confirmation, building regulations and any party wall matters.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about dormer loft conversions in Grantham
How long does it take?
Usually 6 to 9 weeks on site.
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 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.
Do you build dormer loft conversions in Grantham?
Yes. We build dormer loft conversions across Grantham, including postcodes NG31. Every project starts with a free home visit.
How much does a dormer loft conversion cost in Grantham?
In Grantham, a dormer loft conversion typically costs £45,500–£64,500 for a typical rear dormer with en-suite, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.