Loft conversions in Marylebone.
Marylebone · W1 · Marylebone listed apartmentCompleted work, photograph
Roof rooms and mansards for Marylebone houses and top floor flats. Drawn to Westminster’s rules, built by one team.
Marylebone roofs, behind the parapet.
- Mansards
- Often the most discreet roof extension
- Top floors
- The roof space often comes with a lease
- W1
- Georgian terraces, mostly apartments
NU Projects is a design and build company in Fulham SW6, founded in 2010. We handle loft conversions, dormers and mansards in Marylebone W1, under one contract. A loft runs £215 to £425 a sq ft, construction only. Call 020 7731 6841, and a budget estimate typically follows within seven days.
Marylebone is Georgian terraces, most now split into apartments. Roofs hide behind tall parapets.
Many have a valley, or butterfly, roof between the party walls.
Westminster’s roof guide keeps an unbroken run of butterfly roofs as it is.
Where a roof can take more, a mansard behind the parapet is usual.
In a flat, the roof space is often the freeholder’s. Its lease comes first.
What Westminster allows on a Marylebone roof.
- Council
- City of Westminster, for planning and listed building consent alike.
- Butterfly roofs
- An unbroken run of them normally rules out a roof extension.
- Finished terraces
- A terrace already completed with roof storeys is not normally extended again.
- Long views
- Roofs exposed to long views from public spaces are not normally extended.
- Listed buildings
- Listed consent can cover the roof structure and the top floor rooms.
- Flats
- A flat has no householder permitted development rights. Roof changes need planning.
Source: Westminster’s Roofs guide to alterations and extensions on domestic buildings. Read on 6 October 2026. Policies change, so we read them again for your address.
Our work under Westminster’s rules.
Marylebone·Apartment
Marylebone listed apartment
A Grade II listed apartment in Marylebone. The period rooms were kept, and a kitchen fitted.
See the project
Mayfair·Apartment
Mayfair apartment
A Mayfair apartment in Westminster, refitted with joinery by Cochrane Bespoke.
See the projectCompleted work, photographs
What loft conversion costs in Marylebone.
£215 to £425a sq ft, construction only. Our loft band.
£140k to £220kA mansard loft. A project total, from our 2026 cost guide.
£90k to £140kA dormer loft. A project total, from our 2026 cost guide.
A mansard on a listed terrace needs more drawing, and more time.
The band is per square foot, construction only. The guide figures are project totals.
Fees, party wall costs, contingency and VAT sit outside both.
What Marylebone owners ask about lofts.
In Marylebone
Lofts nearby
- Loft conversion across London
- Loft conversion in St John’s Wood
- Loft conversion in Highgate
- Loft conversion in Fulham
- Loft conversion in Notting Hill
- Mayfair
- Fitzrovia and Bloomsbury
- Hampstead and St John’s Wood
Further reading, from the journal
Can I add a mansard to a Marylebone terrace?
Sometimes. Westminster often sees a mansard as the most discreet roof extension.
It is resisted on terraces already complete, or with butterfly roofs.
We study the whole terrace before we draw.
What is a butterfly roof in Marylebone?
A V-shaped roof, dipping to a central gutter between the party walls.
It hides behind the front parapet.
Westminster normally keeps unbroken runs of them as they are.
Can I build into the roof above my Marylebone flat?
Often the freeholder owns that space, so a new lease is needed.
That sits alongside planning, not instead of it.
Your solicitor handles the lease. We handle the design and consent.
Is a loft possible in a listed Marylebone house?
Sometimes, with listed building consent as well as planning.
The original roof structure is often part of the listing.
We record it first, then design around what must stay.
What does a loft conversion in Marylebone cost?
A mansard loft totals £140k to £220k, from our 2026 cost guide.
Our loft band is £215 to £425 a sq ft, construction only.
Listed work often sits high in that band.
Tell us about your home in Marylebone.
Your name and one way to reply are enough. It goes straight to the studio.
- Already have an architect or designer? We build to their design. Working with your designer
- An NDA on request, and your home is never published without your consent. How we work in confidence