Name: Extension Builder
Brand: HaMuch
SKU: extension-renovation
Rating: 4.65 (10 reviews)

Find affordable W4 extension builders

Prices range from cheapest £38/hour and £241/day (True Linear) to £50/hour and £313/day (Ferdas Design & Build Ltd) - average £44/hr and £278/day

HaMuch is Excellent

Local W4 extension builders & latest jobs

"UC beam install 2.5m only (calculations done, building control notification done, no pretty boxing etc.)" - TW8, job posted 09/03/26

"Hi there, I'm reaching out regarding a live opportunity at Heathrow Airport for the design, manufacture, and installation of a pre-fabricated pedestrian bridge next to the Longford Link Bridge. The contract is valued between £150k–£250k and runs until Jan 2027. CAS accreditation is required. If..." - W4, job posted 12/06/25

"Loft conversion" - W12, job posted 21/04/25

"Loft conversion" - W12, job posted 20/04/25

"Loft conversion" - W12, job posted 23/10/24

"Flat roof extension for a period mews terraced house. We'd like a bedroom extension with full bathroom and a roof top terrace. Footprint is roughly 8.5m x 6m." - W6, job posted 06/10/24

"Mansard loft conversion" - SHEPHERD'S BUSH, job posted 26/09/24

"Garage" - W3, job posted 18/06/24

"Side return extension" - SW13, job posted 24/08/23

"Basement conversion" - W4, job posted 07/08/23

Quickly find an Extension Builder in W4

Use these steps to find Extension Builders in W4 for FREE!

Post your job: Click "Get quotes" and briefly describe your job.
Enter your details: We’ll match you with Extension Builders in W4. 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 W4 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 Chiswick
Extension Builders in Acton
Extension Builders in Barnes
Extension Builders in Hammersmith
Extension Builders in Mortlake
Extension Builders in Shepherd's Bush
Extension Builders in Brentford
Extension Builders in Kew
Extension Builders in Ealing
Extension Builders in West Kensington

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 - £26,200

Garden office - £10,200

Granny annexe - £87,200

Build a flat roof extension - £22,200

Convert a Garage - £16,200

Hip to gable loft conversion - £42,200

Convert a bungalow loft - £29,200

Build a dormer loft conversion - £42,200

Build a swimming pool - £81,200

Build a Mansard loft conversion - £52,200

Concrete foundations - £6,450

Underpin a building - £17,700

Two storey extension - £88,300

Convert a basement - £39,750

Side return extension - £43,750

Loft conversion - £35,625

Garage - £18,700

Single storey extension - £59,000

Outbuilding - £10,200

Install an RSJ - £2,400

Build a kitchen extension - £42,200

More extensions & conversions cost guides...

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