# Builders in Harrow

Canonical URL: https://mirion.uk/areas/harrow/

> Extensions, loft conversions and renovations in Harrow, from Pinner and Stanmore to Harrow on the Hill, with Harrow's design guide and 30 conservation areas.

We carry out extensions, loft conversions and renovations across the London Borough of Harrow, where most homes are 1920s and 1930s semi-detached and detached houses built as the Metropolitan line pushed out from London.

Harrow is classic Metro-land. Apart from historic centres such as Harrow on the Hill, Pinner village and Stanmore, most of the borough was built up between the wars along the railway lines, with estates of semi-detached and detached houses at Rayners Lane, North Harrow, Hatch End, Kenton, Harrow Weald and Stanmore.

That shows in the 2021 Census: 65% of Harrow's 89,600 households lived in a house, a higher share than in Brent, Barnet or Ealing. 37% lived in semi-detached houses, 17% in terraced houses and 11% in detached houses, while a third lived in flats.

Because so many houses share the same interwar designs, the same improvements come up again and again: hip-to-gable loft conversions with rear dormers, single-storey rear kitchen extensions, two-storey side extensions over the old garage, and refurbishments that open up the ground floor. The details still vary from street to street, especially in the borough's conservation areas.

Harrow Council judges householder applications against its [Residential Design Guide SPD](https://www.harrow.gov.uk/planning-developments/residential-design) \(2010\), which includes Harrow's long-standing 45-degree code for protecting neighbours' windows. Its preferred loft conversion for semi-detached and terraced houses is a hip-to-gable with a rear dormer, and it says there is generally no scope for first-floor or two-storey rear extensions on mid-terraced houses. We summarise the detail on our [Harrow loft conversions](https://mirion.uk/areas/harrow/loft-conversions/) and [Harrow extensions](https://mirion.uk/areas/harrow/extensions/) pages.

Harrow has 30 conservation areas, grouped into Harrow on the Hill, Pinner, Stanmore and Edgware, and Harrow Weald. Each group has its own supplementary planning document with appraisals, management strategies and maps showing any Article 4 directions, published on the [council's conservation pages](https://www.harrow.gov.uk/planning-developments/biodiversity-conservation). Open land in the north of the borough is Green Belt, where extensions face stricter limits.

Building work in Harrow: common questions

What is Harrow's 45-degree code?

It is the test Harrow uses to protect light and outlook from neighbouring windows. Extensions of two or more storeys should not cross a 45-degree line drawn from the nearest protected window next door, and a vertical version of the test also applies. Single-storey extensions are judged on the site circumstances and Harrow's householder guidance.

How many conservation areas does Harrow have?

Thirty, according to the council. They are grouped into four supplementary planning documents covering Harrow on the Hill, Pinner, Stanmore and Edgware, and Harrow Weald, and the council's online finder checks a postcode.

Do you cover the whole of Harrow?

Yes, including Pinner, Hatch End, Stanmore, Harrow on the Hill, North Harrow, Rayners Lane, Harrow Weald, Kenton, Wealdstone and South Harrow.

- Local planning authority: London Borough of Harrow
- Postcode districts: HA1, HA2, HA3, HA5, HA7
- Work Mirion has carried out here: Extensions, loft conversions and renovations

## Pages

- [House extensions in Harrow](https://mirion.uk/areas/harrow/extensions/index.md): Rear, side and two-storey house extensions in Harrow, with the council's Residential Design Guide rules on depth, height, set-backs and the 45-degree code.
- [Loft conversions in Harrow](https://mirion.uk/areas/harrow/loft-conversions/index.md): Hip-to-gable and dormer loft conversions in Harrow: the council's preferred designs, set-back distances, detached-house rules and permitted development.
- [Home renovations in Harrow](https://mirion.uk/areas/harrow/renovations/index.md): Renovating 1930s semis and period houses in Harrow: opening up layouts, rewiring, new kitchens and bathrooms, plus conservation area and Article 4 checks.
- [Builders in Pinner](https://mirion.uk/areas/harrow/pinner/index.md): Loft conversions, extensions and renovations in Pinner, HA5, for 1930s semis, detached houses and period cottages, with Pinner's conservation areas explained.
- [Builders in Hatch End](https://mirion.uk/areas/harrow/hatch-end/index.md): Extensions, loft conversions and renovations for detached and semi-detached houses in Hatch End, HA5, with local housing figures and Harrow planning guidance.
- [Builders in Stanmore](https://mirion.uk/areas/harrow/stanmore/index.md): Extensions, loft conversions and renovations in Stanmore and Canons Park, HA7: large detached homes, Kerry Avenue and other conservation areas, Harrow rules.
- [Builders in Harrow on the Hill](https://mirion.uk/areas/harrow/harrow-on-the-hill/index.md): Renovations, extensions and loft conversions in Harrow on the Hill, HA1 and HA2: eight conservation areas, period houses and the planning care they need.
- [Builders in North Harrow](https://mirion.uk/areas/harrow/north-harrow/index.md): Loft conversions and extensions for 1930s semis in North Harrow and Rayners Lane, HA2, with housing figures, Harrow's design guide and local conservation areas.
- [Builders in Harrow Weald](https://mirion.uk/areas/harrow/harrow-weald/index.md): Loft conversions, extensions and renovations for 1930s semis in Harrow Weald, HA3, with local housing figures, Green Belt edges and Harrow conservation areas.