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 Wandsworth?
In Wandsworth, 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 Wandsworth. 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 |
Your quote will depend mainly on:
- Dormer size and roof structure
- En-suite or bathroom
- Staircase position
- Built-in storage and finishes
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 Wandsworth?
Approvals for a dormer loft conversion in Wandsworth 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.
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
Handled as part of most dormer loft conversions:
- Steel beams and new floor joists
- New staircase and fire-safe escape route
- Measured survey and head-height check
- Dormer structure, roof covering and windows
- Party wall notices for shared walls
- Building control completion certificate
How long does it take?
Allow 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 Wandsworth
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 Wandsworth or close by in Battersea, Chelsea and Fulham, a free home visit is the first step.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 02
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 03
Approvals
Planning or permitted development confirmation, building regulations and any party wall matters.
- 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 Wandsworth
How much does a dormer loft conversion cost in Wandsworth?
In Wandsworth, 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.
Do you build dormer loft conversions in Wandsworth?
Yes. We build dormer loft conversions across Wandsworth, including postcodes SW18 and SW95. Every project starts with a free home visit.
How long does it take?
Usually 6 to 9 weeks on site.
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.
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.