Looking for experienced extension builders in Barnet? The Construction Collective designs and delivers fully managed home extensions across North London and Hertfordshire, including rear, side-return, wrap-around, kitchen, single-storey and double-storey extensions.
Add space, light and value to your home with a fully managed house extension from The Construction Collective. We design and build house extensions in Barnet, North London and Hertfordshire — including rear extensions, side-return extensions, wrap-around extensions, kitchen extensions, single-storey extensions and double-storey extensions.
Get an instant cost estimate for your extension, loft conversion, renovation or new build — tailored to your project in under 60 seconds.
As experienced extension builders in Barnet, we give you a clear, itemised quotation from the outset and a dedicated project manager for the whole build. We coordinate structural works, roofing, glazing, plumbing, electrics, kitchens and final decoration under one contract, so you have a single accountable team rather than a series of separate trades to chase.
From a kitchen extension with bi-fold doors and a roof lantern, through to a full double-storey side extension adding bedrooms and a bathroom upstairs, we deliver home extensions in North London and house extensions in Hertfordshire to a premium standard, with clear pricing and realistic programmes.
We work with your architect or recommend one of ours, manage planning applications, structural design, party-wall awards and building control sign-off — so your extension starts on solid foundations.
House extension builders across North London and Hertfordshire: Barnet, Finchley, Hampstead, Mill Hill, Whetstone, Totteridge, Hendon, Edgware, Radlett, Potters Bar, St Albans and surrounding areas.
Most single-storey rear extensions in Barnet fall under Permitted Development and don't require planning permission, provided they meet size limits. Extensions in conservation areas or above Permitted Development size limits will need full planning permission. We assess this for every client.
A typical single-storey rear extension costs £35,000–£65,000. Side return extensions cost £40,000–£70,000. Wrap-around extensions cost £60,000–£100,000. Double-storey extensions cost £70,000–£120,000. Use our Online Price Guide for an instant estimate.
A typical single-storey rear extension takes 10–14 weeks from start to finish. Double-storey extensions typically take 16–24 weeks. We provide a detailed programme at quotation stage.
We build all types of extension including single-storey rear, side return, wrap-around, double-storey, kitchen extensions and garden room extensions. Visit our dedicated extension sub-pages for full details on each type.
Yes — bi-fold and sliding doors are extremely popular and we install them on the majority of our extensions. We work with trusted glazing suppliers and can advise on the best specification for your project and budget.
Yes — typically 10–20% in the North London market. For properties in Barnet, Finchley and Hampstead, this regularly represents £80,000–£200,000 in added value.
In most cases no — the main disruption is during rear wall removal and structural steel installation, which typically takes 1–2 weeks. After that, the build is largely external and disruption to your daily life is minimal.
Yes — where planning permission is required, we manage the entire application process including preparation of planning drawings, planning statements and all liaison with the London Borough of Barnet planning department.
A turnkey single-storey rear extension and full ground floor reconfiguration in East Barnet (EN4), featuring extensive structural steel knock-throughs, precision subfloor screeding, and complete architectural fit-out.
A substantial architect-designed ground floor extension in Winchmore Hill — a complex, fully managed project including party wall agreements, delivered to the highest specification.
A fully managed single storey rear extension in Waltham Cross — extending the ground floor living space with quality finishes and full building regulations compliance throughout.
A transformative wrap-around rear extension creating a sun-drenched open-plan kitchen, living area and utility.
Get an instant cost estimate for your extension, loft conversion, renovation or new build — tailored to your project in under 60 seconds.
We work throughout North London and Hertfordshire. Choose your area for local guidance, planning insight and recent projects near you.
Book a free, no-obligation consultation. We'll visit your home, listen to your brief and tell you honestly what's possible.
Or message us directly on WhatsApp — we typically respond within the hour.
