From £18,548
Experienced extension builder ready to quote for your work. J&J Building Solutions is the best extension builder in SE20. No obligation free quotes...
From £18,700
Relax... you have found a reliable extension builder in SE20. Derryard Construction Ltd is a friendly and reliable company based in SE20 who consid...
From £18,468
B J CULLEN BUILDERS are here to help customers who need an Extension Builder in SE20. We offer a competitive rate to complete all your extension bu...
From £18,532
Relax... you have found a reliable extension builder in SE20. Major Building Contractors Ltd is a friendly and reliable company based in SE20 who c...
From £18,684
Need to find an Extension Builder near you for all your extension buildering work?
Sz Builders provides a local, trusted extension builderi...
From £19,212
Experienced extension builder ready to quote for your work. Render is the best extension builder in SE20. No obligation free quotes and many happy ...
From £18,396
Experienced extension builder ready to quote for your work. Jhon is the best extension builder in SE20. No obligation free quotes and many happy cu...
From £18,380
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 £18,692
NIECEIC / NAAPIT GASSAFE WATER REGULATIONS We offer services towards completion of high end construction projects to dis...
From £18,812
skilled worker who specializes in completing a wide range of building and renovation projects

Builders charge between £18,380 (Can design and Construction based in Ig11) and £19,212 (Render based in IG1) in SE20 to build a garage, but these costs are only estimates.
Comparing extension builders estimates for building a garage gives you an idea of who will be better value, but the best way to compare costs is to get actual quotes.
Get real quotes to build a new garage in SE20 by posting a job with HaMuch and we will send it to extension builders in SE20.
| Borough in London |
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| Garage in Penge |
| Garage in Sydenham |
| Garage in Crystal Palace |
| Garage in South Norwood |
| Garage in Beckenham |
| Garage in Forest Hill |
| Garage in Dulwich |
| Garage in Thornton Heath |
| Garage in Tulse Hill |
| Garage in Catford |
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