From £22,400
Starfish Properties is a trusted extension builder serving customers in City Of Westminster and the surrounding area. Contact us to today to get a ...
From £22,088
Dominic Payte - Design & Build is an established extension buildering business in City Of Westminster. We come highly recommended and provide compe...
From £21,944
Hestia Contractors Ltd are here to help customers who need an Extension Builder in City Of Westminster. We offer a competitive rate to complete all...
From £22,040
Independent construction company we have wide range of experience, including newconstruction, renovation, design build and retail stores. We provid...
From £22,232
We are specialised in: demolition services, foundation services, property extension, general bricklaying, internal renovation and configuration, ca...
From £22,432
Reliable and experienced extension builders with competitive rates and good at keeping within budget. Happy to provide examples of extension builde...
From £22,064
Experienced extension builder ready to quote for your work. Cornerstone is the best extension builder in City Of Westminster. No obligation free qu...
From £21,984
JK Doors is a trusted extension builder serving customers in City Of Westminster and the surrounding area. Contact us to today to get a competitive...
From £22,288
Grand Phase Ltd is a trusted extension builder serving customers in City Of Westminster and the surrounding area. Contact us to today to get a comp...
From £22,312
Teammax LTD are here to help customers who need an Extension Builder in City Of Westminster. We offer a competitive rate to complete all your exten...

A flat roof extension ranges from the cheapest of £21,944 (Hestia Contractors Ltd based in W1B) to the dearest of £22,432 (Sehem Design based in W1F), but these are just estimates. While they give you an idea of who will be better value, the best way to compare costs is to get real quotes.
Find out how much your flat roof extension will cost in City Of Westminster by posting a job with HaMuch. We'll send it to extension builders in City Of Westminster.
"Flat roof extension for a period mews terraced house. We'd like a bedroom extension with full bathroom and a roof top terrace. Footprint is roughly 8.5m x 6m." - W6, job posted 10/06/24
"Flat roof extension" - E5, job posted 01/01/70
| Location in UK | Hourly Rate | Daily Rate |
|---|---|---|
| Build A Flat Roof Extension near London | £45 | £274 |
| Build A Flat Roof Extension near Camden Town | £44 | £277 |
| Build A Flat Roof Extension near Belgravia | £44 | £276 |
| Build A Flat Roof Extension near Chelsea | £44 | £276 |
| Build A Flat Roof Extension near Lambeth | £44 | £275 |
| Build A Flat Roof Extension near Kensington | £44 | £277 |
| Build A Flat Roof Extension near Islington | £45 | £276 |
| Build A Flat Roof Extension near Fulham | £44 | £277 |
| Build A Flat Roof Extension near Camberwell | £44 | £276 |
| Build A Flat Roof Extension near Bethnal Green | £45 | £276 |
Whether you’re looking to extend your kitchen with a side return extension or you want to convert your basement into a liveable space, read our cost guides to get an idea of how much each project costs before getting a more accurate quote from our database of reliable tradespeople.

Underpin a building - £17,678

Two storey extension - £88,268

Build a timber frame extension - £26,178

Build a swimming pool - £81,178

Single storey extension - £58,568

Side return extension - £43,507

Install an RSJ - £2,378

Outbuilding - £10,178

Build a Mansard loft conversion - £52,178

Loft conversion - £35,423

Build a kitchen extension - £42,178

Hip to gable loft conversion - £42,178

Granny annexe - £87,178

Garden office - £10,178

Convert a Garage - £16,178

Garage - £18,678

Build a flat roof extension - £22,178

Build a dormer loft conversion - £42,178

Concrete foundations - £6,428

Convert a bungalow loft - £29,178

Convert a basement - £39,507