From £22,032
Relax... you have found a reliable extension builder in E20. Major Building Contractors Ltd is a friendly and reliable company based in E20 who con...
From £21,272
LOCAL COMPANY WITH A TAILORED SERVICE TO ALL BUILDING WORKSYour A2Z building needsLOFT SPACE from £12,000LOFT DORMER from &...
From £22,712
Experienced extension builder ready to quote for your work. Render is the best extension builder in E20. No obligation free quotes and many happy c...
From £22,312
Local Boiler Plumbing & Heating Services is an established and experienced local extension builder in E20. Please contact us for a free, no obligat...
From £21,968
B J CULLEN BUILDERS are here to help customers who need an Extension Builder in E20. We offer a competitive rate to complete all your extension bui...
From £21,984
Reliable and experienced extension builders with competitive rates and good at keeping within budget. Happy to provide examples of extension builde...
From £21,992
Sky Property Group is a trusted extension builder serving customers in E20 and the surrounding area. Contact us to today to get a competitive quote...
From £21,880
Member since August 2025
Reliable and experienced extension builders with competitive rates and good at keeping within budget. Happy to provide examples of extension builde...
From £22,184
Need to find an Extension Builder near you for all your extension buildering work?
Sz Builders provides a local, trusted extension builderi...
From £22,424
A firm that believes in quality, doesn't cut on the key values that creates a ideal home or business. We take on all jobs working to your budget

A flat roof extension ranges from the cheapest of £21,272 (RLUK & Co.Ltd based in IG3) to the dearest of £22,712 (Render based in IG1), 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 E20 by posting a job with HaMuch. We'll send it to extension builders in E20.
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 - £17,576

Two storey extension - £88,114

Build a timber frame extension - £26,076

Build a swimming pool - £81,076

Single storey extension - £56,520

Side return extension - £42,355

Install an RSJ - £2,276

Outbuilding - £10,076

Build a Mansard loft conversion - £52,076

Loft conversion - £34,463

Build a kitchen extension - £42,076

Hip to gable loft conversion - £42,076

Granny annexe - £87,076

Garden office - £10,076

Convert a Garage - £16,076

Garage - £18,576

Build a flat roof extension - £22,076

Build a dormer loft conversion - £42,076

Concrete foundations - £6,326

Convert a bungalow loft - £29,076

Convert a basement - £38,355