Name: Extension Builder
Brand: HaMuch
SKU: extension-renovation
Rating: 4.7 (20 reviews)

Find affordable Cardiff extension builders

Prices range from cheapest £16/hour and £130/day (PK CONSTRUCTION) to £55/hour and £246/day (RDL BUILDING SERVICES LTD) - average £32/hr and £209/day

HaMuch is Excellent

Local Cardiff extension builders & latest jobs

"Side return extension" - CF24, job posted 21/08/26

"Hello A kitchen extension is required. Full planning has been received and structural drawings/recommendations received. Would you be interested in providing a quote? Thank you Jackie" - CF14, job posted 05/06/26

"Loft conversion" - CF23, job posted 16/05/26

"Loft conversion" - CARDIFF, job posted 01/11/25

"Kitchen extension" - CARDIFF, job posted 31/10/25

"Side return extension" - CF24, job posted 21/09/25

"Porch with toilet and shower to be built onto front of house" - CF14, job posted 24/06/25

"Build a garden office, Build a dormer loft conversion" - CF23, job posted 03/06/25

"RSJ installation to open up kitchen and utility room. About 2m wide." - CARDIFF, job posted 22/04/25

"RSJ installation" - CARDIFF, job posted 22/04/25

"Single storey extension" - CF24, job posted 09/04/25

"Looking for a single storey side return to extend kitchen / living space." - CF23, job posted 25/03/25

"Side return extension" - CF24, job posted 25/03/25

"Looking for a single storey side return to extend kitchen / living space." - CF23, job posted 25/03/25

"Double height side extension with single story rear to my existing semi-detached in Cardiff. Planning permission received." - CF14, job posted 11/03/25

"Double height side extension and single story rear" - CF14, job posted 11/03/25

"Side return extension" - CF24, job posted 11/01/25

"Loft conversion with en suite" - CARDIFF, job posted 29/12/24

"Loft conversion" - CARDIFF, job posted 20/11/24

"Loft conversion" - CARDIFF, job posted 23/09/24

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 Cardiff extension builders rates

Compare Cardiff extension builders rates (excluding VAT or callout charges)
Location in UK	Hourly Rate	Daily Rate
Extension Builders near Cardiff	£34	£219
Extension Builders near Penarth	£35	£218
Extension Builders near Caerphilly	£33	£208
Extension Builders near Barry	£33	£218
Extension Builders near Church Village	£34	£214
Extension Builders near Risca	£32	£218
Extension Builders near Newport	£41	£233
Extension Builders near Pontypridd	£33	£211
Extension Builders near Cwmbran	£43	£219
Extension Builders near Weston-super-Mare	£33	£253

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 - £25,704

Garden office - £9,704

Granny annexe - £86,704

Build a flat roof extension - £21,704

Convert a Garage - £15,704

Hip to gable loft conversion - £41,704

Convert a bungalow loft - £28,704

Build a dormer loft conversion - £41,704

Build a swimming pool - £80,704

Build a Mansard loft conversion - £51,704

Concrete foundations - £5,954

Underpin a building - £17,204

Two storey extension - £87,556

Convert a basement - £34,170

Side return extension - £38,170

Loft conversion - £30,975

Garage - £18,204

Single storey extension - £49,080

Outbuilding - £9,704

Install an RSJ - £1,904

Build a kitchen extension - £41,704

More extensions & conversions cost guides...

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