From £2,632
Island design & Construction Ltd are here to help customers who need an Extension Builder in SE8. We offer a competitive rate to complete all your ...
From £2,104
Reliable and experienced extension builders with competitive rates and good at keeping within budget. Happy to provide examples of extension builde...
From £2,320
CG Design & Build is a boutique architectural design agency with in-house construction teams, delivering unique one-off residential and commercial...
From £2,216
WiseContract are here to help customers who need an Extension Builder in SE8. We offer a competitive rate to complete all your extension buildering...
From £2,648
We pride ourselves on providing a professional, caring, and high-quality service and always meet our customers’ needs. Each contractor that works...
From £2,576
Need an Extension Builder in SE8? Exquisite Design & Build Ltd has been helping local clients (5 mile radius) with their extension buildering jobs ...
From £2,512
Need to find an Extension Builder near you for all your extension buildering work?
blitbolt ltd provides a local, trusted extension builder...
From £2,400
We have a creative eye and like a challenge, often building bespoke and creative buildings and furniture. This is mixed with a wide experience of m...
From £2,544
MARMAREX is a trusted extension builder serving customers in SE8 and the surrounding area. Contact us to today to get a competitive quote for exten...
From £2,512
We are a London-based contractor with significant experience in prime property construction and refurbishment, delivering projects for our clients ...

How much RSJs cost for supply and installation varies depending on the size, type and load-bearing properties, but in SE8 it ranges from £2,104 (CG Design and Build LTD. based in e14) to £2,648 (DWL Construction Ltd based in SE14).
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 SE8 by posting a job with HaMuch and we will send it to extension builders in SE8.
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 - £17,746

Two storey extension - £88,370

Build a timber frame extension - £26,246

Build a swimming pool - £81,246

Single storey extension - £59,928

Side return extension - £44,272

Install an RSJ - £2,446

Outbuilding - £10,246

Build a Mansard loft conversion - £52,246

Loft conversion - £36,060

Build a kitchen extension - £42,246

Hip to gable loft conversion - £42,246

Granny annexe - £87,246

Garden office - £10,246

Convert a Garage - £16,246

Garage - £18,746

Build a flat roof extension - £22,246

Build a dormer loft conversion - £42,246

Concrete foundations - £6,496

Convert a bungalow loft - £29,246

Convert a basement - £40,272