From £17,876
Need an Extension Builder in Greater London? Saintflexs has been helping local clients (10 mile radius) with their extension buildering jobs for m...
From £17,612
Pineapple Interiors is an established extension buildering business in Greater London. We come highly recommended and provide competitive quotes fo...
From £17,660
Nicholas James Construction is an established extension buildering business in Greater London. We come highly recommended and provide competitive q...
From £17,588
Reliable and experienced extension builders with competitive rates and good at keeping within budget. Happy to provide examples of extension builde...
From £17,876
Travel London Ltd is an established and experienced local extension builder in Greater London. Please contact us for a free, no obligation quote an...
From £17,796
AAB Tile Installation & Repairs are here to help customers who need an Extension Builder in Greater London. We offer a competitive rate to complete...
From £17,820
Relax... you have found a reliable extension builder in Greater London. PROBUILD (SE) LTD is a friendly and reliable company based in Greater Londo...
From £16,956
Highly dedicated company to deliver exceptional customer service
From £17,628
Relax... you have found a reliable extension builder in Greater London. Upwards and Outwards is a friendly and reliable company based in Greater Lo...
From £17,572
Trusted and professional extension builder in Greater London. Experienced in all extension buildering work and keeping within budget and on quote. ...

Underpinning ranges from £16,956 (London Quality Construction Group Limited based in BR2) to £17,876 (Saintflexs based in BR1), but the final cost will depend on the method of underpinning used, how much of your foundations need underpinning and where you live.
Comparing extension builders estimates for underpinning gives you an idea of who will be better value but the best way to compare costs is to get actual quotes.
Get quotes to underpin your home in Greater London by posting a job with HaMuch and we will send it to extension builders in Greater London.
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 - £17,638

Two storey extension - £88,208

Build a timber frame extension - £26,138

Build a swimming pool - £81,138

Single storey extension - £57,768

Side return extension - £43,057

Install an RSJ - £2,338

Outbuilding - £10,138

Build a Mansard loft conversion - £52,138

Loft conversion - £35,048

Build a kitchen extension - £42,138

Hip to gable loft conversion - £42,138

Granny annexe - £87,138

Garden office - £10,138

Convert a Garage - £16,138

Garage - £18,638

Build a flat roof extension - £22,138

Build a dormer loft conversion - £42,138

Concrete foundations - £6,388

Convert a bungalow loft - £29,138

Convert a basement - £39,057