From £87,352
Experienced extension builder ready to quote for your work. Mayfair Design is the best extension builder in W1J. No obligation free quotes and many...
From £87,024
Luxe Refurbs is an established extension buildering business in W1J. We come highly recommended and provide competitive quotes for your work.
From £87,040
We Love Build - Three Arches is an established extension buildering business in W1J. We come highly recommended and provide competitive quotes for ...
From £87,472
We are a Design and Build Company, based in London.We focus on super prime and luxury residential renovations in and around London and internationa...
From £87,104
Trusted and professional extension builder in W1J. Experienced in all extension buildering work and keeping within budget and on quote. The Maybria...
From £87,384
Experienced extension builder ready to quote for your work. Future Homes Design and Build is the best extension builder in W1J. No obligation free ...
From £87,256
Originally established in 1996 ELV8 has set the highest standards within the building industry, achieving success by winning numerous gold awards f...
From £87,096
Need to find an Extension Builder near you for all your extension buildering work?
Pillar Contractors Ltd provides a local, trusted extensi...
From £87,400
Starfish Properties is a trusted extension builder serving customers in W1J and the surrounding area. Contact us to today to get a competitive quot...
From £85,208
Here at London Design and Build, our team of architects, interior designers, structural engineers and contractors, offer a bespoke, turn-key servic...

Building a granny annexe ranges from £85,208 (London Design And Build based in SW1A) to £87,472 (We Love Build based in W1J), but these are just estimates that can help give you an idea of who will be better value in your area.
The best thing to do is to get quotes to build a granny annexe in W1J by posting a job with HaMuch. We will send it to extension builders in W1J who will be happy to help you.
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 - £17,534

Two storey extension - £88,050

Build a timber frame extension - £26,034

Build a swimming pool - £81,034

Single storey extension - £55,672

Side return extension - £41,878

Install an RSJ - £2,234

Outbuilding - £10,034

Build a Mansard loft conversion - £52,034

Loft conversion - £34,065

Build a kitchen extension - £42,034

Hip to gable loft conversion - £42,034

Granny annexe - £87,034

Garden office - £10,034

Convert a Garage - £16,034

Garage - £18,534

Build a flat roof extension - £22,034

Build a dormer loft conversion - £42,034

Concrete foundations - £6,284

Convert a bungalow loft - £29,034

Convert a basement - £37,878