From £17,628
Experienced extension builder ready to quote for your work. Top Builders is the best extension builder in Thornton Heath. No obligation free quotes...
From £17,764
Peng Construction & Property Maintenance is an established extension buildering business in Thornton Heath. We come highly recommended and provide ...
From £18,700
Member since August 2025
Banga decoration. Is Base in south London for number of year Banga decoration is a small company. Wich provide an excellent job to the custom...
From £17,716
Building Plus Company London Ltd is an established extension buildering business in Thornton Heath. We come highly recommended and provide competit...
From £17,740
Need to find an Extension Builder near you for all your extension buildering work?
VDL Construction Ltd provides a local, trusted extension...
From £17,468
Experienced extension builder ready to quote for your work. Croft Structural Engineers is the best extension builder in Thornton Heath. No obligati...
From £17,716
Experienced extension builder ready to quote for your work. Atkins Builders is the best extension builder in Thornton Heath. No obligation free quo...
From £18,020
Need an Extension Builder in Thornton Heath? Fredibuilder has been helping local clients (10 mile radius) with their extension buildering jobs for...
From £17,452
Experienced extension builder ready to quote for your work. A & P Master Construction is the best extension builder in Thornton Heath. No obligatio...

Underpinning ranges from £17,076 (M & J Building Construction based in CR7) to £18,700 (Banga Decoration based in CR7), 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 Thornton Heath by posting a job with HaMuch and we will send it to extension builders in Thornton Heath.
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 - £17,728

Two storey extension - £88,342

Build a timber frame extension - £26,228

Build a swimming pool - £81,228

Single storey extension - £59,560

Side return extension - £44,065

Install an RSJ - £2,428

Outbuilding - £10,228

Build a Mansard loft conversion - £52,228

Loft conversion - £35,888

Build a kitchen extension - £42,228

Hip to gable loft conversion - £42,228

Granny annexe - £87,228

Garden office - £10,228

Convert a Garage - £16,228

Garage - £18,728

Build a flat roof extension - £22,228

Build a dormer loft conversion - £42,228

Concrete foundations - £6,478

Convert a bungalow loft - £29,228

Convert a basement - £40,065