From £2,536
We make the adage ‘House is where the heart is’, a reality for the house-owners.We are an empathetic housebuilder that delivers elegance and du...
From £2,496
Archway Greater London, N19
We pride ourselves on our ability to provide unmatched construction, renovation and refurbishment services to homeowners, designers and architects ...
From £2,088
Reliable and experienced extension builders with competitive rates and good at keeping within budget. Happy to provide examples of extension builde...
From £2,336
Our building services company Brothers Group have been helping customers in North, East and West London and the surrounding area by providing profe...
From £2,248
Need an Extension Builder in Archway? Avocado Sweets Design Studio has been helping local clients (5 mile radius) with their extension buildering j...
From £2,624
Archway, N19
ARCHWAY DESIGN+BUILD LTD are here to help customers who need an Extension Builder in Archway. We offer a competitive rate to complete all your exte...
From £2,160
Experienced extension builder ready to quote for your work. D.W Baker is the best extension builder in Archway. No obligation free quotes and many ...
From £2,184
Andreas Thomas Demetri is a trusted extension builder serving customers in Archway and the surrounding area. Contact us to today to get a competiti...
From £2,328
RAM Build Construction Ltd is an established and experienced local extension builder in Archway. Please contact us for a free, no obligation quote ...
From £2,200
Need an Extension Builder in Archway? Bok Services Ltd has been helping local clients (5 mile radius) with their extension buildering jobs for many...

How much RSJs cost for supply and installation varies depending on the size, type and load-bearing properties, but in Archway it ranges from £2,088 (Warren House Construction Ltd based in N19) to £2,624 (ARCHWAY DESIGN+BUILD LTD based in N19).
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 Archway by posting a job with HaMuch and we will send it to extension builders in Archway.
"RSJ re-installation" - N16, job posted 04/10/25
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 - £17,620

Two storey extension - £88,180

Build a timber frame extension - £26,120

Build a swimming pool - £81,120

Single storey extension - £57,400

Side return extension - £42,850

Install an RSJ - £2,320

Outbuilding - £10,120

Build a Mansard loft conversion - £52,120

Loft conversion - £34,875

Build a kitchen extension - £42,120

Hip to gable loft conversion - £42,120

Granny annexe - £87,120

Garden office - £10,120

Convert a Garage - £16,120

Garage - £18,620

Build a flat roof extension - £22,120

Build a dormer loft conversion - £42,120

Concrete foundations - £6,370

Convert a bungalow loft - £29,120

Convert a basement - £38,850