From £17,548
Experienced extension builder ready to quote for your work. J&J Building Solutions is the best extension builder in TW16. No obligation free quotes...
1 review
From £17,692
NIECEIC / NAAPIT GASSAFE WATER REGULATIONS We offer services towards completion of high end construction projects to dis...
"Did callout made safe my elctrical work thanks" - reviewed 16/05/23, REECYRUSSO
From £17,524
Need the extension buildering job done quickly without breaking the bank? SH Enterprise offer fast, reliable, and affordable extension buildering s...
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 £17,836
Aerea is a trusted extension builder serving customers in TW16 and the surrounding area. Contact us to today to get a competitive quote for extensi...
From £17,892
Need an Extension Builder in TW16? Samuele Paolini has been helping local clients (5 mile radius) with their extension buildering jobs for many ye...
From £17,780
Member since August 2026
Relax... you have found a reliable extension builder in TW16. ABC Associates STRUCTURES 4 U is a friendly and reliable company based in TW16 who co...
From £17,692
Need an Extension Builder in TW16? VA Structures has been helping local clients (10 mile radius) with their extension buildering jobs for many year...
From £17,780
Trusted and professional extension builder in TW16. Experienced in all extension buildering work and keeping within budget and on quote. DC Build &...
From £17,932
DP Services is a fully insured friendly local company which has been trading since 2002 and delivers high quality building work in domestic extensi...

Underpinning ranges from £17,524 (SH Enterprise based in EC1V) to £17,932 (DP Services based in RG41), 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 TW16 by posting a job with HaMuch and we will send it to extension builders in TW16.
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 - £17,749

Two storey extension - £88,373

Build a timber frame extension - £26,249

Build a swimming pool - £81,249

Single storey extension - £59,976

Side return extension - £44,299

Install an RSJ - £2,449

Outbuilding - £10,249

Build a Mansard loft conversion - £52,249

Loft conversion - £36,083

Build a kitchen extension - £42,249

Hip to gable loft conversion - £42,249

Granny annexe - £87,249

Garden office - £10,249

Convert a Garage - £16,249

Garage - £18,749

Build a flat roof extension - £22,249

Build a dormer loft conversion - £42,249

Concrete foundations - £6,499

Convert a bungalow loft - £29,249

Convert a basement - £40,299