House extension in Herne Hill

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

On the west side, Lambeth’s Herne Hill Conservation Area, first designated in December 2007, covers commercial and residential buildings of around 1900 near the road’s junctions with Half Moon Lane and Milkwood Road, in red or yellow stock brick under tile or slate. The 2012 statement finds commercial premises on the ground floor of the vast majority, often with storage or homes above; the one exception is Herne Hill Mansions, a wholly residential mansion block with a mature front garden. It notes that building east of the railway tended to be later, with detached and semi-detached houses in bigger gardens.

Opposite, most of the adjoining properties on the Southwark side fall in the Stradella Road Conservation Area, designated on 26 September 2000, which covers Stradella and Winterbrook Roads and bordering properties on Burbage Road and Half Moon Lane. Its appraisal describes mostly single-family houses with a small number of flats: principally semi-detached, on two floors with attic rooms, in plain red brick laid in Flemish bond, originally roofed mainly in natural Welsh slate, with mostly double-hung timber sash windows. A pocket of post-war houses replaced war-damaged ones in Stradella Road.

Southwark’s Sunray Estate Conservation Area, designated on 20 January 2009, lies on Denmark Hill in North Dulwich and includes part of the road Herne Hill. Built between 1920 and 1922 as cottage housing, it is described by the council as a small garden suburb. Its appraisal sets rendered main streets against brick-faced enclaves of flats and attached houses, with larger detached and semi-detached houses on Red Post Hill, white-painted wooden casements with small panes, and privet hedges with wooden gates about one metre high.

Local design and consent context

Lambeth’s Brockwell Park Conservation Area, first designated on 10 December 1983 and extended on 24 March 1999, includes the park and the houses adjoining its south and east sides; its character appraisal exists only as a 2020 consultation draft, not an adopted document. Nearby Lambeth conservation areas include Poet’s Corner, designated on 12 October 1998, a mid-to-late 19th-century development of Chaucer, Spenser, Shakespeare and Milton Roads, and the Peabody Estate on Rosendale Road, designated on 24 March 1999, social housing from 1901 onwards in blocks of flats and terraced houses.

Neither appraisal carries an adoption date; the Stradella Road one cites national guidance of March 2010, so it is no older than that. Given an unaltered roofscape, it treats roof extensions and changes to the basic roof form as generally unacceptable, full-width rear extensions as normally unacceptable and side extensions or link blocks that close the gaps between houses as unlikely to be acceptable. Aluminium or uPVC replacements should always be avoided, and further losses of front gardens, walls and planting will be resisted wherever possible. It also records a tree preservation order at 25 Burbage Road.

The Sunray appraisal finds dormers and roof extensions unlikely to be acceptable on the estate’s repetitive roofscape, and two-storey rear extensions or ones not set back from side boundaries unlikely too. As a general guide it expects rear extensions to stay within the line of the flank walls and no deeper than 3.5 metres from the house, while noting that a particular site may justify exceeding some criteria. It prefers secondary glazing behind original windows to replacement double glazing, calls aluminium, uPVC and picture windows without glazing bars unsuitable, and finds front-garden hardstanding out of character.

Access and site planning

Check the council before booking anything for the street, since Southwark and Lambeth follow different rules. In Southwark, the skip company applies for the licence at least 7 days before delivery, a scaffolding or hoarding licence is applied for at least 15 working days ahead, and a parking bay suspension needs seven days’ notice. In Lambeth, only the skip company can obtain a skip licence, a highways licence covers scaffolding, hoarding, fencing, gantries and stored materials, and a standard suspension, including one for a skip, needs 10 or more working days’ notice.

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

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