Name: Extension Builder
Brand: HaMuch
SKU: extension-renovation
Rating: 4.65 (20 reviews)

Find affordable B21 extension builders

Cheapest £24/hour & £196/day (Bhogal Construction) to £45/hour & £375/day (Sperin Interiors) - average £30/hour & £241/day

Local B21 extension builders with reviews/jobs - Sort by rates or availability

"Build a kitchen extension" - B8, job posted 16/09/26

"Install an RSJ. For bow window replacement" - WS5, job posted 15/09/26

"Loft conversion" - WS10, job posted 08/05/26

"Loft conversion" - B68, job posted 06/05/26

"RSJ installation" - BIRMINGHAM, job posted 13/04/26

"Dormer loft conversion" - B62, job posted 17/03/26

"Door into garagefrom kitchen how much" - B74, job posted 20/02/26

"Garage conversion (separate from main house) into a bedroom" - B42, job posted 17/02/26

"Garden self contained annex" - B68, job posted 10/11/25

"Two storey extension" - WEST MIDLANDS, job posted 05/10/25

"Concrete foundation" - B29, job posted 03/09/25

"New Wetroom for special needs with wheelchair access. Complete build with material,plumbing,wall panels,floor tiles.shower, toilet etc.this will be built joined with a living room. Quotes required.Thanks" - SANDWELL, job posted 26/08/25

"Two storey extension" - WEST MIDLANDS, job posted 03/08/25

"Two storey extension" - B68, job posted 21/07/25

"Need an extension builder" - SANDWELL, job posted 13/06/25

"Two storey extension" - WEST MIDLANDS, job posted 08/06/25

"Side return extension" - BIRMINGHAM, job posted 24/02/25

"Build an outbuilding" - B44, job posted 15/02/25

"WET ROOM WITH WHEELCHAIR ACCESS" - SANDWELL, job posted 05/02/25

"2 metres front extension and 3 meters back extension" - WS1, job posted 07/01/25

What are the best ways to avoid problems when paying the Extension Builder?

The most important thing is do avoid handing over cash or paying large sums in advance. Be wary of paying cash for a cheaper job, i.e. to avoid VAT, you may be going down a slippery slope of not doing things properly which may eventually mean your job is also not done properly.

Agree when you intend to pay, ideally after you are satisfied with the completed job. If it is a big job agree a schedule of staged payments which is fair to both parties.

To avoid bad tradespeople and to ensure you can find them should they not answer a mobile;

Get proper contact details and check them yourself
Check if the company is verified on the Companies House website
Get phone details, ideally a land line or 0800 number and check it
Get a physical office address

Before the job starts should I agree standards of quality and behaviour?

Get quotes in writing by email or in person if possible. Getting quotes online or by text is ok (make sure you accept the offer by replying). For large projects make a written agreement, schedule of works and snagging plans as part of a working document. Also;

Agree expected quality of workmanship and materials in advance
When will work start and when will project be finished, what happens if project over runs ?
How long is the guarantee on work and materials eg 12 months
Discuss onsite behaviour in advance (no smoking, swearing or using mobile phones for non-work purposes)
Agree that your Extension Builder will remove all debris and rubbish and what level of tidying up you want after job

Compare B21 extension builders rates

Compare B21 extension builders rates (excluding VAT or callout charges)
Location in UK	Hourly Rate	Daily Rate
Extension Builders near Smethwick	£29	£226
Extension Builders near Birmingham	£29	£227
Extension Builders near West Bromwich	£29	£227
Extension Builders near Oldbury	£29	£227
Extension Builders near Sandwell	£29	£229
Extension Builders near Rowley Regis	£29	£226
Extension Builders near Wednesbury	£29	£227
Extension Builders near Tipton	£29	£227
Extension Builders near Halesowen	£29	£227
Extension Builders near Walsall	£29	£226

Job estimates from extension builders near you

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.

Build a timber frame extension - £25,888

Garden office - £9,888

Granny annexe - £86,888

Build a flat roof extension - £21,888

Convert a Garage - £15,888

Hip to gable loft conversion - £41,888

Convert a bungalow loft - £28,888

Build a dormer loft conversion - £41,888

Build a swimming pool - £80,888

Build a Mansard loft conversion - £51,888

Concrete foundations - £6,138

Underpin a building - £17,388

Two storey extension - £87,832

Convert a basement - £36,240

Side return extension - £40,240

Loft conversion - £32,700

Garage - £18,388

Single storey extension - £52,760

Outbuilding - £9,888

Install an RSJ - £2,088

Build a kitchen extension - £41,888

More extensions & conversions cost guides...

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