Name: Extension Builder
Brand: HaMuch
SKU: extension-renovation
Rating: 4.75 (2 reviews)

Find affordable Welwyn Garden City extension builders

Prices range from cheapest £17/hour and £165/day (Complex Construction) to £48/hour and £307/day (PRIMEEXPERT) - average £41/hr and £266/day

HaMuch is Excellent

Local Welwyn Garden City extension builders & latest jobs

"Single storey extension" - WELWYN, job posted 31/08/25

"We are small builders looking quote for foundations ,groundworks and drainage - soakways Thanks Harsha.R" - AL8, job posted 16/02/25

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 Welwyn Garden City extension builders rates

Compare Welwyn Garden City extension builders rates (excluding VAT or callout charges)
Location in UK	Hourly Rate	Daily Rate
Extension Builders near Welwyn Garden City	£42	£268
Extension Builders near Hatfield	£64	£283
Extension Builders near Hertford	£46	£289
Extension Builders near Potters Bar	£43	£273
Extension Builders near Harpenden	£86	£315
Extension Builders near St Albans	£63	£288
Extension Builders near Ware	£47	£296
Extension Builders near Cheshunt	£48	£285
Extension Builders near Stevenage	£44	£282
Extension Builders near Hoddesdon	£46	£296

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 - £26,240

Garden office - £10,240

Granny annexe - £87,240

Build a flat roof extension - £22,240

Convert a Garage - £16,240

Hip to gable loft conversion - £42,240

Convert a bungalow loft - £29,240

Build a dormer loft conversion - £42,240

Build a swimming pool - £81,240

Build a Mansard loft conversion - £52,240

Concrete foundations - £6,490

Underpin a building - £17,740

Two storey extension - £88,360

Convert a basement - £40,200

Side return extension - £44,200

Loft conversion - £36,000

Garage - £18,740

Single storey extension - £59,800

Outbuilding - £10,240

Install an RSJ - £2,440

Build a kitchen extension - £42,240

More extensions & conversions cost guides...

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