Member since October 2026
We are polite, punctual and respectful small construction business. We take pride in all our work.
Silicone Render System Ltd is a plastering company based in Porthcawl, with over 20 years’ experience in the plastering trade. W...
Barlam Drylining Ltd are here to help customers who need an Extension Builder in Mountain Ash. We offer a competitive rate to complete all your ext...
Need an Extension Builder in Mountain Ash? P.D.Builders has been helping local clients (20 mile radius) with their extension buildering jobs for ma...
Very reliable honest and hard working guarantee all work clean and tidy first class work
Experienced extension builder ready to quote for your work. JA Building Maintenance is the best extension builder in Mountain Ash. No obligation fr...
Experienced extension builder ready to quote for your work. TOR BUILD is the best extension builder in Mountain Ash. No obligation free quotes and ...
T Porter Buiding is an established and experienced local extension builder in Mountain Ash. Please contact us for a free, no obligation quote and c...
Relax... you have found a reliable extension builder in Mountain Ash. Charles Marshall Contracting Ltd is a friendly and reliable company based in ...
Sharif General Builder is an established and experienced local extension builder in Mountain Ash. Please contact us for a free, no obligation quote...

Underpinning ranges from £16,700 (A.Gaddarn Builders based in NP11) to £19,580 (Silicone Rendering Systems Ltd based in CF36), but the final cost will depend on the method of underpinning used, how much of your foundations need underpinning and where you live.
Comparing extension builders estimates for underpinning gives you an idea of who will be better value but the best way to compare costs is to get actual quotes.
Get quotes to underpin your home in Mountain Ash by posting a job with HaMuch and we will send it to extension builders in Mountain Ash.
| Location in UK | Hourly Rate | Daily Rate |
|---|---|---|
| Underpin A Building near Rhondda, Cynon, Taff | £31 | £209 |
| Underpin A Building near Rhondda | £31 | £206 |
| Underpin A Building near Pontypridd | £33 | £211 |
| Underpin A Building near Aberdare | £32 | £212 |
| Underpin A Building near Merthyr Tydfil | £33 | £220 |
| Underpin A Building near Church Village | £34 | £214 |
| Underpin A Building near Tredegar | £30 | £217 |
| Underpin A Building near Caerphilly | £33 | £208 |
| Underpin A Building near Ebbw Vale | £30 | £217 |
| Underpin A Building near Risca | £32 | £218 |
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 - £17,487

Two storey extension - £87,981

Build a timber frame extension - £25,987

Build a swimming pool - £80,987

Single storey extension - £54,744

Side return extension - £41,356

Install an RSJ - £2,187

Outbuilding - £9,987

Build a Mansard loft conversion - £51,987

Loft conversion - £33,630

Build a kitchen extension - £41,987

Hip to gable loft conversion - £41,987

Granny annexe - £86,987

Garden office - £9,987

Convert a Garage - £15,987

Garage - £18,487

Build a flat roof extension - £21,987

Build a dormer loft conversion - £41,987

Concrete foundations - £6,237

Convert a bungalow loft - £28,987

Convert a basement - £37,356