# Builders in Mill Hill

Canonical URL: https://mirion.uk/areas/barnet/mill-hill/

> Extensions, loft conversions and renovations in Mill Hill, NW7: interwar semis near the Broadway, the conservation village and Barnet's 2026 extension rules.

We work across Mill Hill, NW7, from the semi-detached and detached houses around Mill Hill Broadway and Mill Hill East to period cottages in the conservation village on The Ridgeway.

Mill Hill has three distinct parts. The original village on The Ridgeway, with the shortest high street in London, became a country retreat from the seventeenth century. Mill Hill Broadway grew from the 1890s onwards, especially in the early twentieth century, after the Midland Railway station opened in 1868. Mill Hill East has seen large new housing developments on redeveloped sites such as the former gas works.

At the 2021 Census, 62% of households in Mill Hill Park, Mill Hill Broadway, Mill Hill East and Copthall lived in houses: 30% semi-detached, 17% terraced and 15% detached. Median semi-detached prices were about £705,000 to £895,000 in the year to March 2026.

Around the Broadway, the common projects are rear kitchen extensions, hip-to-gable lofts and side extensions on interwar semis. In and around the village, they are careful renovations and modest extensions to older buildings.

The Mill Hill conservation area covers the village and looks out over Green Belt countryside in both directions. Barnet describes it as about 260 houses, mainly brick and weatherboard cottages typical of rural Middlesex, mixed with large institutional buildings. Changes there need a conservation-led design, and Green Belt policy limits extensions on the open land around it.

Elsewhere in Mill Hill, Barnet's 2026 guidance applies. For a semi-detached house, it sets a maximum depth of 3.5 metres for a single-storey rear extension, up to 4 metres high with eaves no higher than 3 metres, and asks for two-storey side extensions to keep a 1-metre gap to the boundary at first floor, particularly where gaps between houses are part of the street's character.

Building work in Mill Hill: common questions

Is Mill Hill village a conservation area?

Yes. The Mill Hill conservation area covers the historic village around The Ridgeway, which Barnet describes as about 260 houses with Green Belt countryside on both sides. Expect a planning application for most external changes there.

How deep can a rear extension be on a Mill Hill semi?

Barnet's June 2026 guidance sets a maximum of 3.5 metres for a single-storey rear extension to a semi-detached house \(3 metres on a terrace, 4 metres detached\). A larger extension already confirmed through the prior approval process can be built as approved.

- Local planning authority: London Borough of Barnet
- Postcode districts: NW7
- Work Mirion has carried out here: Extensions, loft conversions and renovations