Find a builder to make your building structurally sound

RSJs support your new extension or other construction to ensure that your property is structurally sound. They are crucial parts of your building work that mustn't be ignored, and must be installed by a professional.  To see prices and availability for your job click Get quotes.

HaMuch is Excellent

Install an RSJ cost in S21 - Sort by rates or availability

From £2,064

(last active 08/09/26)
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MGG CONSTRUCTION LTD

Trusted and professional extension builder in S21. Experienced in all extension buildering work and keeping within budget and on quote. MGG CONSTRU...

From £2,104

(last active 09/04/26)
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Maison Frais

Looking to Transform Your Home Space?Maison Frais are Space Solution Specialists based in S. Yorkshire. We help TRANSFORM people's family homes to ...

From £2,056

(last active 08/02/26)
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C ROWLEY (SELFBUILD)

C ROWLEY (SELFBUILD) is an established and experienced local extension builder in S21. Please contact us for a free, no obligation quote and compet...

From £2,336

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S. & A. Parsons (Building Contractors) Limited

S. & A. Parsons (Building Contractors) Limited is a trusted extension builder serving customers in S21 and the surrounding area. Contact us to toda...

From £2,112

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Oliver Wild Ltd

Oliver Wild Ltd is an established extension buildering business in S21. We come highly recommended and provide competitive quotes for your work.

From £2,384

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Maison Frais

Trusted and professional extension builder in S21. Experienced in all extension buildering work and keeping within budget and on quote. Maison Frai...

RSJ cost in S21

Estimates for install an rsj near S21

How much RSJs cost for supply and installation varies depending on the size, type and load-bearing properties, but in S21 it ranges from £2,056 (C ROWLEY (SELFBUILD) based in S43) to £2,384 (Maison Frais based in S26).

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 S21 by posting a job with HaMuch and we will send it to extension builders in S21.


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Estimates for common extension builder jobs in S21;

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.

More extensions & conversions cost guides...