Name: Extension Builder
Brand: HaMuch
SKU: extension-renovation
Rating: 4.79 (7 reviews)

Find affordable Knebworth extension builders

Prices range from cheapest £17/hour and £165/day (Complex Construction) to £50/hour and £317/day (R. Newman Construction) - average £41/hr and £267/day

HaMuch is Excellent

Local Knebworth extension builders, reviews & latest jobs

"Outbuilding" - SG2, job posted 01/06/26

"Can i get a builder for an extension quotation please - require 1first floor building on top of my garage and a revamped, heat-proof conservatory if you deal with this - reasonably priced please, thank you." - SG2, job posted 21/04/26

"Single storey extension" - STEVENAGE, job posted 08/11/25

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

"I would to build an extension on top of my garage, planning stage at the moment but I would like to have an experienced builders intake, realistic cost analysis with a plan to use the builder throughout too. Thanks." - SG2, job posted 04/06/25

"Front of house extension. End of terrace property." - SG2, job posted 30/04/25

"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 Knebworth extension builders rates

Compare Knebworth extension builders rates (excluding VAT or callout charges)
Location in UK	Hourly Rate	Daily Rate
Extension Builders near Stevenage	£44	£282
Extension Builders near Welwyn Garden City	£42	£268
Extension Builders near Hertford	£46	£289
Extension Builders near Hitchin	£43	£283
Extension Builders near East Hertfordshire	£44	£289
Extension Builders near North Hertfordshire	£44	£283
Extension Builders near Hatfield	£64	£283
Extension Builders near Ware	£47	£296
Extension Builders near Harpenden	£86	£315
Extension Builders near Letchworth	£44	£283

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 - £26,208

Garden office - £10,208

Granny annexe - £87,208

Build a flat roof extension - £22,208

Convert a Garage - £16,208

Hip to gable loft conversion - £42,208

Convert a bungalow loft - £29,208

Build a dormer loft conversion - £42,208

Build a swimming pool - £81,208

Build a Mansard loft conversion - £52,208

Concrete foundations - £6,458

Underpin a building - £17,708

Two storey extension - £88,312

Convert a basement - £39,840

Side return extension - £43,840

Loft conversion - £35,700

Garage - £18,708

Single storey extension - £59,160

Outbuilding - £10,208

Install an RSJ - £2,408

Build a kitchen extension - £42,208

More extensions & conversions cost guides...

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