From £22,400
Starfish Properties is a trusted extension builder serving customers in W1 and the surrounding area. Contact us to today to get a competitive quote...
From £22,088
Dominic Payte - Design & Build is an established extension buildering business in W1. We come highly recommended and provide competitive quotes for...
From £21,944
Hestia Contractors Ltd are here to help customers who need an Extension Builder in W1. We offer a competitive rate to complete all your extension b...
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 W1. No obligation free quotes and many hap...
From £21,984
JK Doors is a trusted extension builder serving customers in W1 and the surrounding area. Contact us to today to get a competitive quote for extens...
From £22,288
Grand Phase Ltd is a trusted extension builder serving customers in W1 and the surrounding area. Contact us to today to get a competitive quote for...
From £22,312
Teammax LTD are here to help customers who need an Extension Builder in W1. We offer a competitive rate to complete all your extension buildering j...

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 W1 by posting a job with HaMuch. We'll send it to extension builders in W1.
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