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Select your affordable N21 extension builder
Homeowners look no further if you want a qualified extension builder to work in your home. The00Company Ltd are tidy and neat, providing a quality ...
HOW WE WORK?We are here to design the best places!Our experience includes projects all over the world, from small scaled projects to large resident...
AGK Building Services Ltd is a small family-run business with more than 20 years' experience in the building services industry. We have a team of d...
Renova PMC - bespoke construction, interior designers
We are an experienced team dedicated to designing property in a way that is both beautiful and practical. For most people buying a property is an e...
From £42,168
Arben Neza (Benny)
We are focused on delivering high quality loft conversions, house extensions, full or partial house refurbishment, also maximising the full potent...
From £42,256
Winchmore Hill, N21
Need to find an Extension Builder near you for all your extension buildering work?
S E H BUILDERS LTD provides a local, trusted extension b...
From £41,984
Experienced extension builder ready to quote for your work. TIPS CONSTRUCTION is the best extension builder in N21. No obligation free quotes and m...
From £42,160
Nexlevel - An aspiring construction and refurbishment company situated in the London. As a family-run business that is meshed with love, we believe...
From £42,408
Reliable and experienced extension builders with competitive rates and good at keeping within budget. Happy to provide examples of extension builde...

In N21, prices for dormer loft conversions range from £41,960 (The00Company Ltd based in N13) to £42,432 (AGK Building Services Ltd based in N14), but how much your conversion costs will vary depending on the size of your property, how easy access to your roof is and what you want to use the space for.
The best way to get an accurate price is to compare quotes from extension builders in N21. Post your job on HaMuch now and we'll put you in touch with available extension builders.
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.

Underpin a building - £17,666

Two storey extension - £88,250

Build a timber frame extension - £26,166

Build a swimming pool - £81,166

Single storey extension - £58,328

Side return extension - £43,372

Install an RSJ - £2,366

Outbuilding - £10,166

Build a Mansard loft conversion - £52,166

Loft conversion - £35,310

Build a kitchen extension - £42,166

Hip to gable loft conversion - £42,166

Granny annexe - £87,166

Garden office - £10,166

Convert a Garage - £16,166

Garage - £18,666

Build a flat roof extension - £22,166

Build a dormer loft conversion - £42,166

Concrete foundations - £6,416

Convert a bungalow loft - £29,166

Convert a basement - £39,372