House extension in Stanmore

Connect the added space to the existing home.

Start with the house extension brief

Begin with how the new space will meet the old rooms, garden and circulation. A measured brief should record boundaries, levels, existing drains, neighbouring windows and the parts of the building you intend to keep.

Develop daylight, structure and services alongside the floor plan. Agree which openings and finishes are included, how the existing home will be protected during construction and which decisions need surveys or approval before a quotation.

The local building context

The Stanmore Hill appraisal describes houses and some commercial units from the eighteenth to the early twentieth century on sloping land, among greenery and historic walls. Linear development reflects properties built mainly to serve travellers heading to London along Stanmore Hill, many of whom would have stopped at the Abercorn Arms, an eighteenth-century hotel. Stanmore Hill and upper Green Lane are relatively dense, with small terraced cottages on Green Lane, many fronting the pavement; further down Green Lane, medium-sized detached houses in spacious grounds dominate. Buildings usually do not exceed two storeys, and most are listed or locally listed.

Kerry Avenue is different again. Its appraisal records an unusual concentration of inter-war and post-war houses in the Modern or International Style, laid out symmetrically on the axis of Stanmore Station, which opened on 10 December 1932 and became the terminus of the Metropolitan Line, and the 2013 SPD describes its well-preserved Modernist buildings as forming the earliest domestic group in west London. The houses are two or three storeys, with flat roofs often carrying sundecks and curved bays often holding the stair; all are brick, some designed with render to look like concrete against large Crittall windows.

The name Stanmore and an HA7 postcode do not settle the council, a conservation area boundary, a listing, Article 4 coverage or the consent route. ONS lists Stanmore as an electoral ward in Harrow, while the 2013 SPD notes that the Brockley Hill scheduled monument extends partly into the London Borough of Barnet. Confirm the council for the address first. For a Harrow address, check Harrow’s current conservation area map and Article 4 schedule; for any address, check the listing records, the title or lease and the planning history.

Local design and consent context

The map documents give the designation history: Little Common designated in 1970, extended in 1987 and 2002 and amended in 2013; Stanmore Hill designated in 1975 and extended in 1980, 1991 and 2002; Old Church Lane designated in 1975 and extended five times, most recently in December 2013; and Kerry Avenue designated in 1980 and extended in 1986, 1991 and 1998. Some appraisal dates differ, such as 1969 for Little Common, so rely on the current map for the boundary.

The December 2013 SPD was written to supplement a policy of the replaced 2013 plan; the new plan says conservation area SPDs, appraisals and management plans can provide further material considerations, so ask Harrow how it weighs them for a proposal. The SPD sets a presumption in favour of keeping single-family houses in these conservation areas, and the Stanmore Hill appraisal encourages any extension to sit at the rear, subservient to the house and matching its design and materials.

Harrow counts over 300 listed building entries in the borough and 909 locally listed buildings, which are protected locally by planning policy rather than to the statutory standard. Stanmore Station is locally listed and part of the Kerry Avenue conservation area, and Harrow’s local list of parks and gardens includes Bernays Gardens, Stanmore Recreation Ground and Little Common, Stanmore. Ask Harrow whether a building or garden near the work is on the current lists.

Access and site planning

Plan deliveries, waste and protection for any shared hall or drive before work starts. In Harrow, a skip on the public highway needs a skip licence, which the skip company obtains; scaffolding on the highway needs a licence, issued only to the scaffolding company; and building materials on the highway need a licence even briefly, placed on the carriageway rather than the footway. Allow up to 10 working days for a skip licence or a parking-bay suspension, and never reserve a space with cones or bins. TfL licenses these only on its red routes.

Continue planning

The Stanmore area guide · House extension across London · Hampstead Architecture & Planning · Hampstead Chartered Surveyors

Discuss your project

Tell us what you are planning in Stanmore

Share the property location, the work you have in mind and any drawings or permissions you already have.

£5M public liability, £10M employers’ liability and contractors’ all risks cover.

Design support: Hampstead Architecture & Planning.
Surveying support: Hampstead Chartered Surveyors.