From £17,908
By being involved in a variety of residential and commercial projects, we understand the needs of our clients and can complete different types of r...
From £17,660
Whetstone Greater London, N20
Nava Construction LTD a bespoke solution that will transform any space into a place you feel happy and content.
From £17,516
Reliable and experienced extension builders with competitive rates and good at keeping within budget. Happy to provide examples of extension builde...
From £17,932
Whetstone, N20
Need an Extension Builder in Whetstone? Odp Builders has been helping local clients (5 mile radius) with their extension buildering jobs for many y...
From £17,444
Builder for London is an established and experienced local extension builder in Whetstone. Please contact us for a free, no obligation quote and co...
From £17,788
Whetstone, N20
Trusted and professional extension builder in Whetstone. Experienced in all extension buildering work and keeping within budget and on quote. D.J C...
From £17,532
Relax... you have found a reliable extension builder in Whetstone. A Sparky Technical Building Services is a friendly and reliable company based in...
From £18,084
Reliable and experienced extension builders with competitive rates and good at keeping within budget. Happy to provide examples of extension builde...
From £17,692
I Builder are a well established, reliable and trustworthy company with over twenty years' experience.We are based in Barnet covering Barne...

Underpinning ranges from £17,444 (Builder for London based in N12) to £18,084 (Homeworks Design & Build Ltd based in N20), 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 Whetstone by posting a job with HaMuch and we will send it to extension builders in Whetstone.
"Underpinning" - N20, job posted 03/01/26
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 - £17,702

Two storey extension - £88,304

Build a timber frame extension - £26,202

Build a swimming pool - £81,202

Single storey extension - £59,048

Side return extension - £43,777

Install an RSJ - £2,402

Outbuilding - £10,202

Build a Mansard loft conversion - £52,202

Loft conversion - £35,648

Build a kitchen extension - £42,202

Hip to gable loft conversion - £42,202

Granny annexe - £87,202

Garden office - £10,202

Convert a Garage - £16,202

Garage - £18,702

Build a flat roof extension - £22,202

Build a dormer loft conversion - £42,202

Concrete foundations - £6,452

Convert a bungalow loft - £29,202

Convert a basement - £39,777