Name: Extension Builder
Brand: HaMuch
SKU: extension-renovation
Rating: 4.67 (3 reviews)

Find affordable Cockfosters extension builders

Prices range from cheapest £21/hour and £165/day (Onyx Iv) to £77/hour and £323/day (Homeworks Design & Build Ltd) - average £45/hr and £267/day

HaMuch is Excellent

Local Cockfosters extension builders & latest jobs

"Underpinning" - N20, job posted 01/03/26

"Underpinning" - EN2, job posted 19/12/25

"Loft conversion" - N20, job posted 11/01/24

Quickly find an Extension Builder in Cockfosters

Use these steps to find Extension Builders in Cockfosters for FREE!

Post your job: Click "Get quotes" and briefly describe your job.
Enter your details: We’ll match you with Extension Builders in Cockfosters. We’ll notify you via text or email when an Extension Builder is available to quote.
Select your Extension Builder: Compare Extension Builders interested in working with you. You can use HaMuch to safely message local Cockfosters Extension Builders or phone them directly - you’re in control!

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

Local Extension Builders in London Boroughs

Local Extension Builders in London Boroughs
Borough in London
Extension Builders in Cockfosters
Extension Builders in Whetstone
Extension Builders in High Barnet
Extension Builders in Southgate
Extension Builders in North Finchley
Extension Builders in Friern Barnet
Extension Builders in Winchmore Hill
Extension Builders in Botany Bay
Extension Builders in Palmers Green
Extension Builders in Finchley

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 - £26,192

Garden office - £10,192

Granny annexe - £87,192

Build a flat roof extension - £22,192

Convert a Garage - £16,192

Hip to gable loft conversion - £42,192

Convert a bungalow loft - £29,192

Build a dormer loft conversion - £42,192

Build a swimming pool - £81,192

Build a Mansard loft conversion - £52,192

Concrete foundations - £6,442

Underpin a building - £17,692

Two storey extension - £88,288

Convert a basement - £39,660

Side return extension - £43,660

Loft conversion - £35,550

Garage - £18,692

Single storey extension - £58,840

Outbuilding - £10,192

Install an RSJ - £2,392

Build a kitchen extension - £42,192

More extensions & conversions cost guides...

People in Cockfosters searching for a Extension Builder also viewed...

Painter and Decorator

The Largest Database of UK Trade Rates

At HaMuch we know what tradespeople charge because we have the largest database of rates anywhere in the UK. If you want quotes for jobs at the right price for you, post your jobs with HaMuch and get your home improvements kickstarted straight away!

Appliance Repair Specialist

Conservatory Specialist