Relax... you have found a reliable extension builder in BT7. SM Plumbing & Heating is a friendly and reliable company based in BT7 who consider no ...
From £1,376
Trusted and professional extension builder in BT7. Experienced in all extension buildering work and keeping within budget and on quote. Extended li...

How much RSJs cost for supply and installation varies depending on the size, type and load-bearing properties, but in BT7 it ranges from £1,376 (Extended living by Gilbert-Ash based in BT12) to £1,568 (SM Plumbing & Heating based in BT7).
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 BT7 by posting a job with HaMuch and we will send it to extension builders in BT7.
"RSJ installation" - BELFAST, job posted 09/08/25
| Location in UK | Hourly Rate | Daily Rate |
|---|---|---|
| Install An RSJ near Belfast | £23 | £161 |
| Install An RSJ near Carryduff | £23 | £158 |
| Install An RSJ near Holywood | £23 | £159 |
| Install An RSJ near Lisburn | £24 | £164 |
| Install An RSJ near Comber | £22 | £160 |
| Install An RSJ near Greenisland | £23 | £153 |
| Install An RSJ near Ballygowan | £24 | £183 |
| Install An RSJ near Saintfield | £23 | £162 |
| Install An RSJ near Hillsborough and Culcavy | £25 | £170 |
| Install An RSJ near Crumlin | £26 | £194 |
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 - £16,772

Two storey extension - £86,908

Build a timber frame extension - £25,272

Build a swimming pool - £80,272

Single storey extension - £40,440

Side return extension - £33,310

Install an RSJ - £1,472

Outbuilding - £9,272

Build a Mansard loft conversion - £51,272

Loft conversion - £26,925

Build a kitchen extension - £41,272

Hip to gable loft conversion - £41,272

Granny annexe - £86,272

Garden office - £9,272

Convert a Garage - £15,272

Garage - £17,772

Build a flat roof extension - £21,272

Build a dormer loft conversion - £41,272

Concrete foundations - £5,522

Convert a bungalow loft - £28,272

Convert a basement - £29,310