From £17,812
Reliable and experienced extension builders with competitive rates and good at keeping within budget. Happy to provide examples of extension builde...
From £17,780
Member since August 2026
Relax... you have found a reliable extension builder in HP4. ABC Associates STRUCTURES 4 U is a friendly and reliable company based in HP4 who cons...
From £17,780
Trusted and professional extension builder in HP4. Experienced in all extension buildering work and keeping within budget and on quote. DC Build & ...
From £17,420
NISUP BUILDING SERVICES Company specializes in the domestic and commercial building industry :1. Refurbishm...
From £17,932
Krystian Wojasiewicz is a trusted extension builder serving customers in HP4 and the surrounding area. Contact us to today to get a competitive quo...
From £17,932
Platinum Electrics is a Branch off Platinum Premier Projects who deal in all types of construction projects. Platinum Electrics are based in London...
From £17,612
Trusted and professional extension builder in HP4. Experienced in all extension buildering work and keeping within budget and on quote. D Dan Const...
From £17,684
Experienced extension builder ready to quote for your work. DIAL 1ST CONSTRUCTION LTD is the best extension builder in HP4. No obligation free quot...
From £17,660
Trusted and professional extension builder in HP4. Experienced in all extension buildering work and keeping within budget and on quote. PARKWAY MAI...
From £17,748
C & A Contractors is a trusted extension builder serving customers in HP4 and the surrounding area. Contact us to today to get a competitive quote ...

Underpinning ranges from £17,420 (Nisup Building Services based in HA8) to £17,932 (Krystian Wojasiewicz based in HA9), 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 HP4 by posting a job with HaMuch and we will send it to extension builders in HP4.
| Location in UK | Hourly Rate | Daily Rate |
|---|---|---|
| Underpin A Building near Berkhamsted | £41 | £263 |
| Underpin A Building near Dacorum | £42 | £269 |
| Underpin A Building near Hemel Hempstead | £42 | £270 |
| Underpin A Building near Chesham | £42 | £277 |
| Underpin A Building near Dunstable | £41 | £272 |
| Underpin A Building near Rickmansworth | £42 | £278 |
| Underpin A Building near St Albans | £63 | £288 |
| Underpin A Building near Harpenden | £86 | £315 |
| Underpin A Building near Hazlemere | £40 | £272 |
| Underpin A Building near Luton | £41 | £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 - £17,736

Two storey extension - £88,354

Build a timber frame extension - £26,236

Build a swimming pool - £81,236

Single storey extension - £59,720

Side return extension - £44,155

Install an RSJ - £2,436

Outbuilding - £10,236

Build a Mansard loft conversion - £52,236

Loft conversion - £35,963

Build a kitchen extension - £42,236

Hip to gable loft conversion - £42,236

Granny annexe - £87,236

Garden office - £10,236

Convert a Garage - £16,236

Garage - £18,736

Build a flat roof extension - £22,236

Build a dormer loft conversion - £42,236

Concrete foundations - £6,486

Convert a bungalow loft - £29,236

Convert a basement - £40,155