From £6,298
Experienced extension builder ready to quote for your work. J&J Building Solutions is the best extension builder in SE25. No obligation free quotes...
From £6,450
Relax... you have found a reliable extension builder in SE25. Derryard Construction Ltd is a friendly and reliable company based in SE25 who consid...
From £6,218
B J CULLEN BUILDERS are here to help customers who need an Extension Builder in SE25. We offer a competitive rate to complete all your extension bu...
From £6,282
Relax... you have found a reliable extension builder in SE25. Major Building Contractors Ltd is a friendly and reliable company based in SE25 who c...
From £6,434
Need to find an Extension Builder near you for all your extension buildering work?
Sz Builders provides a local, trusted extension builderi...
From £6,962
Experienced extension builder ready to quote for your work. Render is the best extension builder in SE25. No obligation free quotes and many happy ...
From £6,146
Experienced extension builder ready to quote for your work. Jhon is the best extension builder in SE25. No obligation free quotes and many happy cu...
From £6,130
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 £6,442
NIECEIC / NAAPIT GASSAFE WATER REGULATIONS We offer services towards completion of high end construction projects to dis...
From £6,562
skilled worker who specializes in completing a wide range of building and renovation projects

Concrete foundations range from the £6,130 (Can design and Construction based in Ig11) to £6,962 (Render based in IG1) in SE25.
Comparing extension builders estimates for laying concrete foundations gives you an idea of who will be better value, but the best way to compare costs is to get actual quotes.
Find out the exact cost of laying concrete foundations in SE25 by posting a job with HaMuch. We will send it to extension builders who can give you a detailed quote.
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 - £17,642

Two storey extension - £88,214

Build a timber frame extension - £26,142

Build a swimming pool - £81,142

Single storey extension - £57,848

Side return extension - £43,102

Install an RSJ - £2,342

Outbuilding - £10,142

Build a Mansard loft conversion - £52,142

Loft conversion - £35,085

Build a kitchen extension - £42,142

Hip to gable loft conversion - £42,142

Granny annexe - £87,142

Garden office - £10,142

Convert a Garage - £16,142

Garage - £18,642

Build a flat roof extension - £22,142

Build a dormer loft conversion - £42,142

Concrete foundations - £6,392

Convert a bungalow loft - £29,142

Convert a basement - £39,102