From £2,136
L.D.Design&Build means a holistic approach to building, one simple way of finding everything you need for your building project under the ‘same r...
From £2,072
Need an Extension Builder in NN1? DAB & K&G Building Services has been helping local clients (20 mile radius) with their extension buildering jobs ...
From £1,816
Brickwork specialist with 30 years experience.
From repointing, small repairs up to building extensions and houses.
Stonework...
From £2,392
Relax... you have found a reliable extension builder in NN1. Wright Building is a friendly and reliable company based in NN1 who consider no job as...
From £1,800
M Home Renovations is an established extension buildering business in NN1. We come highly recommended and provide competitive quotes for your work....
From £2,312
Need to find an Extension Builder near you for all your extension buildering work?
The Builders - Northampton Limited provides a local, tru...
From £2,128
Fountain Construction Ltd is an established and experienced local extension builder in NN1. Please contact us for a free, no obligation quote and c...
From £2,448
Samrai Associates was founded by Hars Samrai in Northampton in order to provide clients with a prompt and robust Architectural Service. Over time m...
From £1,608
We have a great team behind us, we offer friendly, competitive and professional service. With years of experience among the trades, there's not muc...
From £2,064
Walsh Builders Ltd is an established and experienced local extension builder in NN1. Please contact us for a free, no obligation quote and competit...

How much RSJs cost for supply and installation varies depending on the size, type and load-bearing properties, but in NN1 it ranges from £1,608 (Artizan Roofing based in NN2) to £2,448 (Samrai Associates Limited based in NN3).
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 NN1 by posting a job with HaMuch and we will send it to extension builders in NN1.
| Location in UK | Hourly Rate | Daily Rate |
|---|---|---|
| Install An RSJ near Northampton | £35 | £239 |
| Install An RSJ near Wellingborough | £39 | £251 |
| Install An RSJ near Daventry | £31 | £230 |
| Install An RSJ near Rushden | £34 | £231 |
| Install An RSJ near Kettering | £34 | £237 |
| Install An RSJ near Milton Keynes | £39 | £263 |
| Install An RSJ near Market Harborough | £31 | £217 |
| Install An RSJ near Rugby | £31 | £224 |
| Install An RSJ near Bletchley | £39 | £265 |
| Install An RSJ near South Bedfordshire | £45 | £278 |
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 - £17,378

Two storey extension - £87,816

Build a timber frame extension - £25,878

Build a swimming pool - £80,878

Single storey extension - £52,552

Side return extension - £40,123

Install an RSJ - £2,078

Outbuilding - £9,878

Build a Mansard loft conversion - £51,878

Loft conversion - £32,603

Build a kitchen extension - £41,878

Hip to gable loft conversion - £41,878

Granny annexe - £86,878

Garden office - £9,878

Convert a Garage - £15,878

Garage - £18,378

Build a flat roof extension - £21,878

Build a dormer loft conversion - £41,878

Concrete foundations - £6,128

Convert a bungalow loft - £28,878

Convert a basement - £36,123