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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 Streatham. No obligation free q...
Greens Gardening & Landscape Property Maintenance
John Mcdonagh
Watch our short video highlighting all our expertise and services here:
more than 10 y...
From £53,200
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 Streatham and the surrounding area. Contact us to today to get a competitive ...
J & D Construction
Trusted and professional extension builder in Streatham. Experienced in all extension buildering work and keeping within budget and on quote. J & D...
Langston Builders
Langston Builders is a trusted extension builder serving customers in Streatham and the surrounding area. Contact us to today to get a competitive ...
Sonik Building Services
Trusted and professional extension builder in Streatham. Experienced in all extension buildering work and keeping within budget and on quote. Sonik...
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 Streatham. We come highly recommended and provide competitive quo...
Tenfold Renovation
Tenfold Renovation
Need to find an Extension Builder near you for all your extension buildering work?
Tenfold Renovation provides a local, trusted extension b...
Mansard loft conversion cost in Streatham
Mansard loft conversions range from the cheapest installation of £52,048 (J&J Building Solutions based in SW16) to the dearest of around £53,200 (Banga Decoration based in CR7).
While these estimates give you a good idea how much you'll pay for a mansard loft conversion, the only way to get an accurate price is to get real quotes from real builders.
Get quotes to install a mansard loft conversion in Streatham by posting a job with HaMuch and we'll send it to extension builders in Streatham.
- How much does a mansard loft conversion cost?
- What is a mansard loft conversion?
- Factors that affect the cost of a mansard loft conversion
- Additional costs to consider with a mansard loft conversion
- How long does a mansard loft conversion take?
- Do I need planning permission for a mansard roof?
- What is the difference between a dormer and a mansard?
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Estimates for common extension builder jobs in Streatham;
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 - £17,864
Two storey extension - £88,546
Build a timber frame extension - £26,364
Build a swimming pool - £81,364
Single storey extension - £62,280
Side return extension - £45,595
Install an RSJ - £2,564
Outbuilding - £10,364
Build a Mansard loft conversion - £52,364
Loft conversion - £37,163
Build a kitchen extension - £42,364
Hip to gable loft conversion - £42,364
Granny annexe - £87,364
Garden office - £10,364
Convert a Garage - £16,364
Garage - £18,864
Build a flat roof extension - £22,364
Build a dormer loft conversion - £42,364
Concrete foundations - £6,614
Convert a bungalow loft - £29,364
Convert a basement - £41,595