From £2,512
Local Boiler Plumbing & Heating Services is an established and experienced local extension builder in CM4. Please contact us for a free, no obligat...
From £2,384
Experienced extension builder ready to quote for your work. CC&D BUILDING LTD is the best extension builder in CM4. No obligation free quotes and m...
From £2,816
HOUSE BUILDING SERVICES LIMITED is a trusted extension builder serving customers in CM4 and the surrounding area. Contact us to today to get a comp...
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...
From £3,784
Propello is an established and experienced local extension builder in CM4. Please contact us for a free, no obligation quote and competitive rates...
From £2,624
Nouvell Decor is a trusted extension builder serving customers in CM4 and the surrounding area. Contact us to today to get a competitive quote for ...
From £2,512
skilled worker who specializes in completing a wide range of building and renovation projects
From £2,440
M&J Brickwork Ltd are a Chelmsford based Bricklaying & General Building company that operate throughout the Essex and South London...
From £2,400
Relax... you have found a reliable extension builder in CM4. Derryard Construction Ltd is a friendly and reliable company based in CM4 who consider...
From £2,168
B J CULLEN BUILDERS are here to help customers who need an Extension Builder in CM4. We offer a competitive rate to complete all your extension bui...

How much RSJs cost for supply and installation varies depending on the size, type and load-bearing properties, but in CM4 it ranges from £2,080 (Can design and Construction based in Ig11) to £3,784 (Propello based in E17).
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 CM4 by posting a job with HaMuch and we will send it to extension builders in CM4.
| Location in UK | Hourly Rate | Daily Rate |
|---|---|---|
| Install An RSJ near Billericay | £38 | £248 |
| Install An RSJ near Brentwood | £39 | £255 |
| Install An RSJ near Chelmsford | £38 | £258 |
| Install An RSJ near Wickford | £39 | £255 |
| Install An RSJ near Basildon | £39 | £251 |
| Install An RSJ near Stanford-le-Hope | £40 | £254 |
| Install An RSJ near Romford | £45 | £274 |
| Install An RSJ near Rayleigh | £39 | £252 |
| Install An RSJ near Thundersley | £38 | £251 |
| Install An RSJ near South Ockendon | £58 | £276 |
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 - £17,872

Two storey extension - £88,558

Build a timber frame extension - £26,372

Build a swimming pool - £81,372

Single storey extension - £62,440

Side return extension - £45,685

Install an RSJ - £2,572

Outbuilding - £10,372

Build a Mansard loft conversion - £52,372

Loft conversion - £37,238

Build a kitchen extension - £42,372

Hip to gable loft conversion - £42,372

Granny annexe - £87,372

Garden office - £10,372

Convert a Garage - £16,372

Garage - £18,872

Build a flat roof extension - £22,372

Build a dormer loft conversion - £42,372

Concrete foundations - £6,622

Convert a bungalow loft - £29,372

Convert a basement - £41,685