# Builders in Harrow Weald

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

> Loft conversions, extensions and renovations for 1930s semis in Harrow Weald, HA3, with local housing figures, Green Belt edges and Harrow conservation areas.

Harrow Weald is a leafy 1930s suburb on the edge of Harrow Weald Common, and our work here is mainly loft conversions and extensions to its semi-detached houses.

Harrow Weald combines a 1930s suburban development with the ancient woodland of Harrow Weald Common to the north. The houses along and off the main roads are mostly semi-detached family homes with hipped roofs, front bays and long back gardens.

It has one of the highest shares of semi-detached houses we have found. At the 2021 Census, 82% of households in Harrow Weald and Belmont lived in houses, and 61% in semi-detached houses. Median semi-detached prices were about £590,000 to £640,000 in the year to March 2026, lower than in Pinner or Stanmore, so extending is often worth comparing with moving.

The common projects are a hip-to-gable loft with a rear dormer, a full-width rear kitchen extension and a side extension replacing the garage. There is no station in the centre of Harrow Weald; Headstone Lane and Harrow & Wealdstone stations are nearby, and most deliveries arrive along the main roads.

Harrow Weald has two conservation areas: Harrow Weald Park, and Brookshill Drive and Grimsdyke Estate, where an Article 4 direction applies to some buildings. Both are covered by Harrow's Harrow Weald Conservation Areas SPD.

Much of the open land to the north, including Harrow Weald Common, is Green Belt, where houses face stricter limits on extensions. Elsewhere, Harrow's Residential Design Guide applies: single-storey rear extensions are judged against the permitted development depths of 3 metres for a semi and 4 metres for a detached house, with heights on the boundary of about 3 metres for a flat roof and 3.5 metres at the mid-point of a pitched roof. For houses in the Green Belt, national policy treats additions that are disproportionate to the original building as inappropriate, so earlier extensions count against what can be added.

Building work in Harrow Weald: common questions

Are there conservation areas in Harrow Weald?

Yes, two: Harrow Weald Park, and Brookshill Drive and Grimsdyke Estate. Some buildings in the latter are covered by an Article 4 direction, which removes permitted development rights.

How high can a single-storey extension be in Harrow?

Harrow's guidance suggests a maximum of 3 metres on the boundary for a flat roof, and 3.5 metres at the mid-point of the roof slope on the boundary for a pitched roof, subject to site circumstances.

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