Name: Extension Builder
Brand: HaMuch
SKU: extension-renovation
Rating: 4.67 (12 reviews)

Need help with a job?

Find affordable NN4 extension builders

Prices range from cheapest £25/hour and £176/day (GW BUILDERS) to £44/hour and £281/day (Samrai Associates Limited) - average £35/hr

HaMuch is Excellent

Local NN4 extension builders

"Loft extension (dormer)" - NN5, job posted 21/08/26

"Granny annexe" - NN5, job posted 04/08/26

"I need a quote for a second-floor extension sized 3m x 3.5m. Work includes structure, walls, insulation, roof, windows, and basic internal finishing, plus connection to the existing house. Please confirm: Total cos with my material and if with your material Time to complet and when you can..." - NORTHAMPTON, job posted 19/11/25

"Side return extension" - NORTHAMPTON, job posted 03/06/25

"Loft conversion" - NORTHAMPTON, job posted 29/01/25

"Loft conversion" - NORTHAMPTON, job posted 10/01/25

"Loft conversion, 2 beds dormer" - NORTHAMPTON, job posted 23/11/24

"Dormer Loft conversion" - NORTHAMPTON, job posted 02/04/24

"Loft conversion" - NORTHAMPTON, job posted 24/03/24

"Basement conversion" - NORTHAMPTON, job posted 13/02/24

"Loft conversion" - NORTHAMPTON, job posted 30/10/23

"Loft conversion" - NORTHAMPTON, job posted 02/09/23

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 NN4 extension builders rates

Compare NN4 extension builders rates (excluding VAT or callout charges)
Location in UK	Hourly Rate	Daily Rate
Extension Builders near Northampton	£35	£239
Extension Builders near Wellingborough	£39	£251
Extension Builders near Daventry	£31	£230
Extension Builders near Milton Keynes	£39	£263
Extension Builders near Rushden	£34	£231
Extension Builders near Kettering	£34	£237
Extension Builders near Bletchley	£39	£265
Extension Builders near Market Harborough	£31	£217
Extension Builders near South Bedfordshire	£45	£278
Extension Builders near Bedford	£45	£278

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 - £25,896

Garden office - £9,896

Granny annexe - £86,896

Build a flat roof extension - £21,896

Convert a Garage - £15,896

Hip to gable loft conversion - £41,896

Convert a bungalow loft - £28,896

Build a dormer loft conversion - £41,896

Build a swimming pool - £80,896

Build a Mansard loft conversion - £51,896

Concrete foundations - £6,146

Underpin a building - £17,396

Two storey extension - £87,844

Convert a basement - £36,330

Side return extension - £40,330

Loft conversion - £32,775

Garage - £18,396

Single storey extension - £52,920

Outbuilding - £9,896

Install an RSJ - £2,096

Build a kitchen extension - £41,896

More extensions & conversions cost guides...

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