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J&J Building Solutions
Experienced extension builder ready to quote for your work. J&J Building Solutions is the best extension builder in Merton. No obligation free quot...
Greens Gardening & Landscape Property Maintenance
John Mcdonagh
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more than 10 y...
From £23,200
Banga Decoration
Sebastian Banga
Member since August 2025
Banga decoration. Is Base in south London for number of year Banga decoration is a small company. Wich provide an excellent job to the custom...
Buci builders ltd
Robert Buci
Buci builders ltd is a trusted extension builder serving customers in Merton and the surrounding area. Contact us to today to get a competitive quo...
J & D Construction
Trusted and professional extension builder in Merton. Experienced in all extension buildering work and keeping within budget and on quote. J & D Co...
Langston Builders
Langston Builders is a trusted extension builder serving customers in Merton and the surrounding area. Contact us to today to get a competitive quo...
Sonik Building Services
Trusted and professional extension builder in Merton. Experienced in all extension buildering work and keeping within budget and on quote. Sonik Bu...
ACE BUILDING CONTRACTORS AND D
Reliable and experienced extension builders with competitive rates and good at keeping within budget. Happy to provide examples of extension builde...
Renaissance Timothy Brewer Ltd
Renaissance Timothy Brewer Ltd is an established extension buildering business in Merton. We come highly recommended and provide competitive quotes...
Flat roof extension cost in Merton
A flat roof extension ranges from the cheapest of £22,048 (J&J Building Solutions based in SW16) to the dearest of £23,200 (Banga Decoration based in CR7), 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 Merton by posting a job with HaMuch. We'll send it to extension builders in Merton.
"Flat roof extension" - CR44, job posted 01/01/70
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Estimates for common extension builder jobs in Merton;
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 - £17,863
Two storey extension - £88,545
Build a timber frame extension - £26,363
Build a swimming pool - £81,363
Single storey extension - £62,264
Side return extension - £45,586
Install an RSJ - £2,563
Outbuilding - £10,363
Build a Mansard loft conversion - £52,363
Loft conversion - £37,155
Build a kitchen extension - £42,363
Hip to gable loft conversion - £42,363
Granny annexe - £87,363
Garden office - £10,363
Convert a Garage - £16,363
Garage - £18,863
Build a flat roof extension - £22,363
Build a dormer loft conversion - £42,363
Concrete foundations - £6,613
Convert a bungalow loft - £29,363
Convert a basement - £41,586