From £2,296
Greater London, SE6
Whether you are looking to build, extend or upgrade we will help. From building to decorating. Our professional team have the skills and experie...
From £2,224
Jeremy Weston, trading as GreenGauge has over 10 years experience working as a Heating Engineer. Fully Insured and Gas Safe Registered.Base...
From £2,352
Catford, SE6
Relax... you have found a reliable extension builder in SE6. S G Painting Contractor Ltd is a friendly and reliable company based in SE6 who consid...
From £2,352
We provide our clients with excellent service and quality. Whether you are looking to extend or upgrade, our professional team has the skills and e...
From £2,448
London, SE6
Baseline Build and Renovate Ltd is an established extension buildering business in SE6. We come highly recommended and provide competitive quotes f...
From £2,512
Construction Surety is an established extension buildering business in SE6. We come highly recommended and provide competitive quotes for your work...
From £2,656
MPN Engineering LTD are here to help customers who need an Extension Builder in SE6. We offer a competitive rate to complete all your extension bui...
From £2,272
Trusted and professional extension builder in SE6. Experienced in all extension buildering work and keeping within budget and on quote. Carai Ltd h...
From £2,512
Pure Building & Maintenance is a family run business with over 35 years' experience. Comprising a team of dedicated professionals who all have the...
From £2,400
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 SE6 it ranges from £2,224 (GreenGauge Heating Limited based in SE6) to £2,656 (MPN Engineering LTD based in BR1).
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 SE6 by posting a job with HaMuch and we will send it to extension builders in SE6.
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 - £17,702

Two storey extension - £88,304

Build a timber frame extension - £26,202

Build a swimming pool - £81,202

Single storey extension - £59,048

Side return extension - £43,777

Install an RSJ - £2,402

Outbuilding - £10,202

Build a Mansard loft conversion - £52,202

Loft conversion - £35,648

Build a kitchen extension - £42,202

Hip to gable loft conversion - £42,202

Granny annexe - £87,202

Garden office - £10,202

Convert a Garage - £16,202

Garage - £18,702

Build a flat roof extension - £22,202

Build a dormer loft conversion - £42,202

Concrete foundations - £6,452

Convert a bungalow loft - £29,202

Convert a basement - £39,777