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 green button.

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From £3,400

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Banga Decoration

Sebastian Banga

Member since August 2025

Banga decoration. Is Base in south London  for number of year  Banga decoration is a small  company. Wich provide an excellent job to the custom...

From £2,344

Last active Nov 26
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Greens Gardening & Landscape Property Maintenance

John Mcdonagh

Watch our short video highlighting all our expertise and services here:

more than 10 y...

From £2,544

Last active Oct 26
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Glenn Miller Builders Limited

Glenn Miller

Relax... you have found a reliable extension builder in SE25. Glenn Miller Builders Limited is a friendly and reliable company based in SE25 who co...

From £2,496

Last active Sep 26
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Aviemore Building Contractors Ltd

Experienced extension builder ready to quote for your work. Aviemore Building Contractors Ltd is the best extension builder in SE25. No obligation ...

From £1,768

Last active Sep 26
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Oaksure Construction

Stuart Bogazzi

Working as a builder for over 20 years now.

Family run business 

Can sort any problem out and help build your dreams.

From £2,456

Last active Sep 26
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Bhagtana & Co Construction

Experienced extension builder ready to quote for your work. Bhagtana & Co Construction is the best extension builder in SE25. No obligation free qu...

From £2,384

Last active Aug 26
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K S BUILDERS (UK) LTD

Trusted and professional extension builder in SE25. Experienced in all extension buildering work and keeping within budget and on quote. K S BUILDE...

From £2,440

Last active Aug 26
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VDL Construction Ltd

Need to find an Extension Builder near you for all your extension buildering work?

VDL Construction Ltd provides a local, trusted extension...

From £2,328

Last active Aug 26
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Top Builders

Experienced extension builder ready to quote for your work. Top Builders is the best extension builder in SE25. No obligation free quotes and many ...

From £2,584

Last active Aug 26
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Howland Building Services

Need to find an Extension Builder near you for all your extension buildering work?

Howland Building Services provides a local, trusted exte...

RSJ cost in SE25

Estimates for install an rsj near SE25

How much RSJs cost for supply and installation varies depending on the size, type and load-bearing properties, but in SE25 it ranges from £1,768 (Oaksure Construction based in CR0) to £3,400 (Banga Decoration based in CR7).

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 SE25 by posting a job with HaMuch and we will send it to extension builders in SE25.


Estimates for common extension builder jobs in SE25;

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...