Khalid Osman
We agree on the work, price and appointment before starting. Our approach focuses on clear communication, punctuality, careful workmanship and leav...
Jay Reid
CK Constructions & Development Ltd is a trusted extension builder serving customers in W1C and the surrounding area. Contact us to today to get a c...
A to Z Builders Ltd are here to help customers who need an Extension Builder in W1C. We offer a competitive rate to complete all your extension bui...
JK Doors is a trusted extension builder serving customers in W1C and the surrounding area. Contact us to today to get a competitive quote for exten...
JM Building Services is a trusted extension builder serving customers in W1C and the surrounding area. Contact us to today to get a competitive quo...
Hussein Eljhani
We are highly professional Builders Company, hones pricing and reliable, we leave all areas clean and tidy.
Buildwiser is a trusted extension builder serving customers in W1C and the surrounding area. Contact us to today to get a competitive quote for ext...
F & F Building Services is an established extension buildering business in W1C. We come highly recommended and provide competitive quotes for your ...
Anthony Sullivan
We build Lofts. We build Extensions. We undertake conversions. Our Terms and conditions apply as shown in our starter packs.

A flat roof extension ranges from the cheapest of £21,976 (A to Z Builders Ltd based in SW1P) to the dearest of £24,320 (Reid and Co Developments Ltd based in NW8), 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 W1C by posting a job with HaMuch. We'll send it to extension builders in W1C.
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 - £18,092

Two storey extension - £88,888

Build a timber frame extension - £26,592

Build a swimming pool - £81,592

Single storey extension - £66,840

Side return extension - £48,160

Install an RSJ - £2,792

Outbuilding - £10,592

Build a Mansard loft conversion - £52,592

Loft conversion - £39,300

Build a kitchen extension - £42,592

Hip to gable loft conversion - £42,592

Granny annexe - £87,592

Garden office - £10,592

Convert a Garage - £16,592

Garage - £19,092

Build a flat roof extension - £22,592

Build a dormer loft conversion - £42,592

Concrete foundations - £6,842

Convert a bungalow loft - £29,592

Convert a basement - £44,160