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 Highgate?
In Highgate, a dormer loft conversion typically costs £62,500–£88,500 for a typical rear dormer with en-suite, including VAT at 20% (standard rate). Prices across London are typically 30% above the UK average for this kind of work, which is reflected in the range for Highgate. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A typical rear dormer with en-suite | £62,500–£88,500 |
| Higher specification | £88,500–£110,500 |
What moves the price most:
- Staircase position
- Built-in storage and finishes
- Dormer size and roof structure
- En-suite or bathroom
Use the guide price tool to see how size and specification change the figure, then ask for a written, itemised quote.
Do you need planning permission for a dormer loft conversion in Highgate?
Before anything is built in Highgate, 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.
Building regulations approval comes from the council’s building control service or a registered building control approver. The work is inspected at key stages, such as foundations, drainage and insulation, and a completion certificate is issued at the end.
We check this for your address before design work starts, so there are no surprises later.
What we handle
The work we manage on a dormer loft conversion:
- Dormer structure, roof covering and windows
- Building control completion certificate
- Measured survey and head-height check
- Party wall notices for shared walls
- Steel beams and new floor joists
- Insulation, plastering, electrics and plumbing
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 Highgate
Victorian and Edwardian terraces dominate many London streets, which is why side return, wraparound and mansard projects are so common here.
If your home is in Highgate or close by in Hampstead, Crouch End and Camden, a free home visit is the first step.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 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
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about dormer loft conversions in Highgate
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.
Who approves a dormer loft conversion in Highgate?
Planning matters in Highgate go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
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 does a dormer loft conversion cost in Highgate?
In Highgate, a dormer loft conversion typically costs £62,500–£88,500 for a typical rear dormer with en-suite, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.