From £2,248
Experienced extension builder ready to quote for your work. J&J Building Solutions is the best extension builder in GU21. No obligation free quotes...
From £2,536
Aerea is a trusted extension builder serving customers in GU21 and the surrounding area. Contact us to today to get a competitive quote for extensi...
From £2,480
Member since August 2026
Relax... you have found a reliable extension builder in GU21. ABC Associates STRUCTURES 4 U is a friendly and reliable company based in GU21 who co...
From £2,392
Need an Extension Builder in GU21? VA Structures has been helping local clients (10 mile radius) with their extension buildering jobs for many year...
From £2,480
Trusted and professional extension builder in GU21. Experienced in all extension buildering work and keeping within budget and on quote. DC Build &...
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 £2,632
DP Services is a fully insured friendly local company which has been trading since 2002 and delivers high quality building work in domestic extensi...
From £2,504
Hi we have 15 years of experience in building and construction industry our specialization is bathrooms and renovations please have a look at the w...
From £2,624
Reliable and experienced extension builders with competitive rates and good at keeping within budget. Happy to provide examples of extension builde...
From £2,104
Elite Construction London Ltd has been one of the top providers of building and remodeling services in London for more than ten years.Our goal is ...

How much RSJs cost for supply and installation varies depending on the size, type and load-bearing properties, but in GU21 it ranges from £2,104 (Elite Construction London Ltd based in TW8) to £2,632 (DP Services based in RG41).
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 GU21 by posting a job with HaMuch and we will send it to extension builders in GU21.
| Location in UK | Hourly Rate | Daily Rate |
|---|---|---|
| Install An RSJ near Woking | £43 | £277 |
| Install An RSJ near New Haw | £43 | £273 |
| Install An RSJ near Guildford | £53 | £298 |
| Install An RSJ near Ascot | £41 | £276 |
| Install An RSJ near Camberley | £41 | £283 |
| Install An RSJ near Ash Vale | £41 | £277 |
| Install An RSJ near Egham | £42 | £266 |
| Install An RSJ near Farnborough | £41 | £273 |
| Install An RSJ near Staines-upon-Thames | £42 | £269 |
| Install An RSJ near Walton-on-Thames | £43 | £277 |
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 - £17,751

Two storey extension - £88,377

Build a timber frame extension - £26,251

Build a swimming pool - £81,251

Single storey extension - £60,024

Side return extension - £44,326

Install an RSJ - £2,451

Outbuilding - £10,251

Build a Mansard loft conversion - £52,251

Loft conversion - £36,105

Build a kitchen extension - £42,251

Hip to gable loft conversion - £42,251

Granny annexe - £87,251

Garden office - £10,251

Convert a Garage - £16,251

Garage - £18,751

Build a flat roof extension - £22,251

Build a dormer loft conversion - £42,251

Concrete foundations - £6,501

Convert a bungalow loft - £29,251

Convert a basement - £40,326