From £2,768
Experienced extension builder ready to quote for your work. Ashtons is the best extension builder in Harpenden. No obligation free quotes and many ...
From £2,512
Trusted and professional extension builder in Harpenden. Experienced in all extension buildering work and keeping within budget and on quote. Home ...
From £2,544
Harpenden, AL5
Trusted and professional extension builder in Harpenden. Experienced in all extension buildering work and keeping within budget and on quote. Peter...
From £2,472
Harpenden, AL5
Experienced extension builder ready to quote for your work. Priolotiling is the best extension builder in Harpenden. No obligation free quotes and ...
From £2,312
4siblings are here to help customers who need an Extension Builder in Harpenden. We offer a competitive rate to complete all your extension builder...
From £2,264
We pride ourselves in offering transparent, collaborative construction services, defining your project, through planning and taking your project t...
From £2,600
Bob's Home Maintenance are here to help customers who need an Extension Builder in Harpenden. We offer a competitive rate to complete all your exte...
From £2,224
In an unstable market house extensions are often the most viable option, helping you to get the most out of the space you have without the addition...
From £2,728
Billy Homan set up Grain Property to provide high-quality design, seamless project delivery, and a commitment to excellent communication throughout...
From £2,184
Abalon is Western Canada’s leading foundation repair and basement waterproofing company, operating in the Edmonton area for over 40 years (50 yea...

How much RSJs cost for supply and installation varies depending on the size, type and load-bearing properties, but in Harpenden it ranges from £2,184 (Abalon Construction based in ZZ99) to £2,768 (Ashtons based in Al5).
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 Harpenden by posting a job with HaMuch and we will send it to extension builders in Harpenden.
| Location in UK | Hourly Rate | Daily Rate |
|---|---|---|
| Install An RSJ near Harpenden | £86 | £315 |
| Install An RSJ near St Albans | £63 | £288 |
| Install An RSJ near Luton | £42 | £276 |
| Install An RSJ near Hatfield | £64 | £283 |
| Install An RSJ near Hemel Hempstead | £42 | £270 |
| Install An RSJ near Welwyn Garden City | £42 | £268 |
| Install An RSJ near Dacorum | £42 | £269 |
| Install An RSJ near Hitchin | £43 | £283 |
| Install An RSJ near Dunstable | £41 | £270 |
| Install An RSJ near Stevenage | £44 | £282 |
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 - £17,761

Two storey extension - £88,391

Build a timber frame extension - £26,261

Build a swimming pool - £81,261

Single storey extension - £60,216

Side return extension - £44,434

Install an RSJ - £2,461

Outbuilding - £10,261

Build a Mansard loft conversion - £52,261

Loft conversion - £36,195

Build a kitchen extension - £42,261

Hip to gable loft conversion - £42,261

Granny annexe - £87,261

Garden office - £10,261

Convert a Garage - £16,261

Garage - £18,761

Build a flat roof extension - £22,261

Build a dormer loft conversion - £42,261

Concrete foundations - £6,511

Convert a bungalow loft - £29,261

Convert a basement - £40,434