# Builders in Barnet Canonical URL: https://mirion.uk/areas/barnet/ > Extensions, loft conversions and renovations in Barnet, from Mill Hill to Hampstead Garden Suburb, under the council's June 2026 extensions guidance. We carry out extensions, loft conversions and renovations across the London Borough of Barnet, from interwar semis in Edgware and Mill Hill to Edwardian houses in Finchley, Hendon and Golders Green. Barnet's character is suburban but varied. The council's own design guidance highlights historic residential areas such as Hampstead Garden Suburb, Totteridge, the Cricklewood Railway Terraces and Monken Hadley, alongside large areas of detached, semi-detached and terraced housing that followed the railways and the Northern line in the late nineteenth and early twentieth centuries. At the 2021 Census, 52% of Barnet's 148,900 households lived in houses: 27% semi-detached, 15% terraced and 10% detached. The other 45% lived in flats. Typical projects range from rear kitchen extensions and hip-to-gable lofts on interwar semis in Edgware, Mill Hill and Hendon, to careful extensions and renovations of Edwardian houses in Finchley and Golders Green and the Arts and Crafts houses of Hampstead Garden Suburb. On 15 June 2026 Barnet adopted its [Sustainable Design and Development Guidance SPD](https://www.barnet.gov.uk/planning-and-building-control/planning-policies-and-local-plan/local-plan-review/sustainable-design), which replaced the Residential Design Guidance SPD of 2016. Part 4 covers residential extensions and alterations, with specific limits for rear, side, roof and basement extensions that we summarise on our [Barnet extensions](https://mirion.uk/areas/barnet/extensions/) and [Barnet loft conversions](https://mirion.uk/areas/barnet/loft-conversions/) pages. Barnet has 16 conservation areas, including Hampstead Garden Suburb, Mill Hill, Totteridge, Hendon Church End, Golders Green, Finchley Church End and Finchley Garden Village. In Hampstead Garden Suburb, the Suburb Trust's consent is also needed for any external change, separately from planning permission. The council publishes character appraisals, boundary maps and Article 4 directions on its [conservation pages](https://www.barnet.gov.uk/planning-and-building-control/conservation-and-heritage/conservation-areas). Part 4 also covers basements, which should project no further than 3 metres beyond the rear wall of a terraced house, 3.5 metres for a semi and 4 metres for a detached house, with front lightwells no more than 1 metre deep. Large areas of open land around Mill Hill and Totteridge are Green Belt, where extensions are limited further. Building work in Barnet: common questions Has Barnet changed its extension guidance? Yes. Barnet adopted the Sustainable Design and Development Guidance SPD on 15 June 2026, replacing the 2016 Residential Design Guidance SPD. Part 4 sets out the council's current expectations for extensions, dormers and basements. How many conservation areas are there in Barnet? Sixteen, from Hampstead Garden Suburb and Totteridge to the Watling Estate, Railway Terraces and Wood Street. The council publishes a character appraisal or boundary map for each. Which parts of Barnet do you cover? We work across Edgware, Mill Hill, Hendon, Finchley, Golders Green, Hampstead Garden Suburb, Totteridge and Whetstone. - Local planning authority: London Borough of Barnet - Postcode districts: HA8, N2, N3, N12, N20, NW4, NW7, NW11 - Work Mirion has carried out here: Extensions, loft conversions and renovations ## Pages - [House extensions in Barnet](https://mirion.uk/areas/barnet/extensions/index.md): Rear, side, wraparound and two-storey extensions in Barnet under the council's June 2026 guidance: depths, heights, garden limits and boundary gaps. - [Loft conversions in Barnet](https://mirion.uk/areas/barnet/loft-conversions/index.md): Loft conversions in Barnet: rear, side and L-shaped dormers, hip-to-gable rules, materials and permitted development under the council's 2026 guidance. - [Home renovations in Barnet](https://mirion.uk/areas/barnet/renovations/index.md): Renovating Edwardian, Arts and Crafts and interwar houses in Barnet, including Hampstead Garden Suburb Trust consent and conservation area checks. - [Builders in Mill Hill](https://mirion.uk/areas/barnet/mill-hill/index.md): Extensions, loft conversions and renovations in Mill Hill, NW7: interwar semis near the Broadway, the conservation village and Barnet's 2026 extension rules. - [Builders in Edgware](https://mirion.uk/areas/barnet/edgware/index.md): Loft conversions, extensions and renovations in Edgware, HA8: interwar semis built after the 1924 tube station, with Barnet and Harrow planning rules. - [Builders in Finchley](https://mirion.uk/areas/barnet/finchley/index.md): Extensions, loft conversions and renovations in Finchley, N3 and N12, for Edwardian and interwar houses, with Barnet's 2026 guidance and conservation areas. - [Builders in Hendon](https://mirion.uk/areas/barnet/hendon/index.md): Loft conversions, extensions and renovations in Hendon, NW4: interwar semis near Hendon Central, older streets at Church End and Barnet's 2026 guidance. - [Builders in Golders Green](https://mirion.uk/areas/barnet/golders-green/index.md): Extensions, loft conversions and renovations in Golders Green, NW11: Edwardian houses built after the 1907 tube station, with Barnet's 2026 guidance. - [Builders in Hampstead Garden Suburb](https://mirion.uk/areas/barnet/hampstead-garden-suburb/index.md): Renovations, extensions and loft conversions in Hampstead Garden Suburb, NW11 and N2: how Trust consent, Barnet planning and Article 4 rules work together. - [Builders in Totteridge](https://mirion.uk/areas/barnet/totteridge/index.md): Extensions, loft conversions and renovations in Totteridge and Whetstone, N20: large detached houses, the 1968 conservation area and Green Belt limits.