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

Find affordable New Malden extension builders

Extension builders rates in New Malden range from £39/hour £245/day (Flanagan Construction Ltd) to £49/hour £313/day (Aranstruct). To see prices and availability now for your job click Get quotes.

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"Build a brick outbuilding, 24ft by 14ft including folding doors. Usage is for gym and office." - KT5, job posted 01/05/26

"Build a hip to gable loft conversion" - KT4, job posted 22/09/25

"Two storey extension on the side and rear, new kitchen, new bathrooms" - WORCESTER, job posted 15/05/25

"Loft conversion" - SURBITON, job posted 11/04/25

"Single storey extension" - WORCESTER, job posted 18/02/25

"Single storey extension" - WORCESTER, job posted 31/01/25

"Loft conversion" - KINGSTON UPON THAMES, job posted 18/11/24

"Loft conversion" - WORCESTER PARK, job posted 31/08/24

"Two Storey Extension plans approved, must be high end builder." - KT2, job posted 01/07/24

"Just a general enquiry" - KT4, job posted 02/10/23

Quickly find an Extension Builder in New Malden

Use these steps to find Extension Builders in New Malden for FREE!

Post your job: Click "Get quotes" and briefly describe your job.
Enter your details: We’ll match you with Extension Builders in New Malden. 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 New Malden 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 New Malden
Extension Builders in Surbiton
Extension Builders in Merton
Extension Builders in Worcester Park
Extension Builders in Kingston Upon Thames
Extension Builders in Coombe
Extension Builders in Long Ditton
Extension Builders in Morden
Extension Builders in North Cheam
Extension Builders in Wimbledon

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 - £26,176

Garden office - £10,176

Granny annexe - £87,176

Build a flat roof extension - £22,176

Convert a Garage - £16,176

Hip to gable loft conversion - £42,176

Convert a bungalow loft - £29,176

Build a dormer loft conversion - £42,176

Build a swimming pool - £81,176

Build a Mansard loft conversion - £52,176

Concrete foundations - £6,426

Underpin a building - £17,676

Two storey extension - £88,264

Convert a basement - £39,480

Side return extension - £43,480

Loft conversion - £35,400

Garage - £18,676

Single storey extension - £58,520

Outbuilding - £10,176

Install an RSJ - £2,376

Build a kitchen extension - £42,176

More extensions & conversions cost guides...

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