From £2,248
Experienced extension builder ready to quote for your work. J&J Building Solutions is the best extension builder in W7. No obligation free quotes a...
From £2,480
Member since August 2026
Relax... you have found a reliable extension builder in W7. ABC Associates STRUCTURES 4 U is a friendly and reliable company based in W7 who consid...
From £2,512
Reliable and experienced extension builders with competitive rates and good at keeping within budget. Happy to provide examples of extension builde...
From £2,400
Relax... you have found a reliable extension builder in W7. Derryard Construction Ltd is a friendly and reliable company based in W7 who consider n...
From £2,168
B J CULLEN BUILDERS are here to help customers who need an Extension Builder in W7. We offer a competitive rate to complete all your extension buil...
From £2,232
Relax... you have found a reliable extension builder in W7. Major Building Contractors Ltd is a friendly and reliable company based in W7 who consi...
From £2,384
Need to find an Extension Builder near you for all your extension buildering work?
Sz Builders provides a local, trusted extension builderi...
From £2,912
Experienced extension builder ready to quote for your work. Render is the best extension builder in W7. No obligation free quotes and many happy cu...
From £2,096
Experienced extension builder ready to quote for your work. Jhon is the best extension builder in W7. No obligation free quotes and many happy cust...
From £2,080
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...

How much RSJs cost for supply and installation varies depending on the size, type and load-bearing properties, but in W7 it ranges from £2,080 (Can design and Construction based in Ig11) to £2,912 (Render based in IG1).
Comparing extension builders estimates for fitting an RSJ gives you an idea of who will be better value but the best way to compare costs is to get actual quotes.
Get rates and quotes to install an RSJ in W7 by posting a job with HaMuch and we will send it to extension builders in W7.
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 - £17,651

Two storey extension - £88,227

Build a timber frame extension - £26,151

Build a swimming pool - £81,151

Single storey extension - £58,024

Side return extension - £43,201

Install an RSJ - £2,351

Outbuilding - £10,151

Build a Mansard loft conversion - £52,151

Loft conversion - £35,168

Build a kitchen extension - £42,151

Hip to gable loft conversion - £42,151

Granny annexe - £87,151

Garden office - £10,151

Convert a Garage - £16,151

Garage - £18,651

Build a flat roof extension - £22,151

Build a dormer loft conversion - £42,151

Concrete foundations - £6,401

Convert a bungalow loft - £29,151

Convert a basement - £39,201