Loft conversion cost in London (2026)
By Kristian Toth, Co-owner, Making World Beautiful · Last updated: 16 October 2026
Short answer
Loft conversions with MWB start from £60,000, depending on type (dormer, hip-to-gable or mansard). Most take 8–12 weeks on site.
Which loft conversion type do I need?
It depends on your roof and planning constraints.
- Rear dormer: most common for terraces
- Hip-to-gable: for semis and end-of-terraces
- Mansard: maximum space, usually needs planning
Do I need planning permission for a loft conversion?
Rear dormers are often permitted development; mansards and anything in a conservation area generally need planning permission.
What hidden costs should I budget for?
Allow roughly 10–15% on top of the build price for fees and contingency. The most common extras in London are:
- Party wall surveyor: typically £700–£1,500 per neighbour if works affect a shared wall
- Structural engineer calculations: usually £500–£2,000
- Building control fees: commonly £800–£2,000 depending on the council
- Skip permits and parking suspensions: charged per week by the borough
- Planning or lawful development certificate fees where needed
Frequently asked questions
How much does a loft conversion cost in London?
With MWB, from £60,000.
How long does a loft conversion take?
Usually 8–12 weeks on site.