From £2,248
Experienced extension builder ready to quote for your work. J&J Building Solutions is the best extension builder in Knaphill. No obligation free qu...
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 £2,384
Experienced extension builder ready to quote for your work. DIAL 1ST CONSTRUCTION LTD is the best extension builder in Knaphill. No obligation free...
From £2,344
ABC Building & Maintenance Contractors Ltd is a trusted extension builder serving customers in Knaphill and the surrounding area. Contact us to tod...
From £2,184
Need an Extension Builder in Knaphill? DIU Builders Group UK has been helping local clients (10 mile radius) with their extension buildering jobs f...
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 £2,360
Homeowners look no further if you want a qualified extension builder to work in your home. LCD Pixel Construction Ltd are tidy and neat, providing ...
From £2,528
Reliable and experienced extension builders with competitive rates and good at keeping within budget. Happy to provide examples of extension builde...
From £2,480
Member since August 2026
Relax... you have found a reliable extension builder in Knaphill. ABC Associates STRUCTURES 4 U is a friendly and reliable company based in Knaphil...

How much RSJs cost for supply and installation varies depending on the size, type and load-bearing properties, but in Knaphill it ranges from £2,184 (DIU Builders Group UK based in HA0) to £2,624 (LALI BUILDERS based in NW10).
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 Knaphill by posting a job with HaMuch and we will send it to extension builders in Knaphill.
| 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 - £17,726

Two storey extension - £88,340

Build a timber frame extension - £26,226

Build a swimming pool - £81,226

Single storey extension - £59,528

Side return extension - £44,047

Install an RSJ - £2,426

Outbuilding - £10,226

Build a Mansard loft conversion - £52,226

Loft conversion - £35,873

Build a kitchen extension - £42,226

Hip to gable loft conversion - £42,226

Granny annexe - £87,226

Garden office - £10,226

Convert a Garage - £16,226

Garage - £18,726

Build a flat roof extension - £22,226

Build a dormer loft conversion - £42,226

Concrete foundations - £6,476

Convert a bungalow loft - £29,226

Convert a basement - £40,047