House extension in Chiswick

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

Grove Park was designated on 11 January 2002; its appraisal says some properties first included in the Strand on the Green Conservation Area in 1968 were transferred to it, and calls it Chiswick’s first large Victorian housing estate, planned for large mansions and recreational areas. On Grove Park Road, Nos. 17–35 and 47–57 (odd) are 1870s Italianate houses of yellow stock brick with stucco, mostly locally listed; most on the south side are two-storey semi-detached houses of the early 1930s, and Nos. 8–18 (even) are flats. Locally listed Hartington Court is a streamline moderne design of 1938.

Bedford Park, begun in 1875, is divided by Woodstock Road: Hounslow’s appraisal puts the west side of that road and the estate westward of it, The Avenue included, in Ealing. Hounslow designated its part on 16 April 1970 and Ealing its own in 1969. Hounslow’s appraisal describes artistically designed houses of moderate size and notes that detached houses are rare, while Ealing’s consultation speaks of a rich variety of styles in the spirit of the Arts and Crafts movement, with Queen Anne Revival references. St Michael and All Angels and The Tabard are both Grade II*.

A W4 postcode and the name Chiswick are labels, not legal tests. They cannot tell you which planning authority deals with an application, whether the house sits inside a conservation area boundary, whether it is on the statutory or local list, or what consents the work requires. On Woodstock Road the answer can change across the street, because the west side is in Ealing and the east in Hounslow, whose Article 4 schedule stops at its own boundary, and the Old Chiswick appraisal describes Chiswick Mall stretching east into Hammersmith, a different borough. Work from the house number: the council’s appraisal maps, Hounslow’s Article 4 schedule and both lists, then turn to the title or lease and to past planning decisions on the property.

Local design and consent context

Hounslow’s conservation areas page says the borough currently has 29 conservation areas, and its download page lists their appraisals and maps. Among those for Chiswick, Strand on the Green’s appraisal was adopted in October 2018 and Old Chiswick’s, for an area designated on 1 May 1969, in Autumn 2019; the Grove Park, Turnham Green and Chiswick House appraisals were each adopted in January 2021. Turnham Green, designated on 4 September 1975, grew westward in 2001 and southward and westward in 2020, and its appraisal traces the green to a larger common where the Battle of Turnham Green was fought in 1642. The Chiswick House Conservation Area was designated on 18 July 1977.

Hounslow’s Article 4 page says its A4D.1 directions cover all properties in the Bedford Park and Gunnersbury Park conservation areas, and the householder leaflet says the properties shown in the schedules are affected and that the directions were confirmed on 24 July 2001. Where development fronts a highway or open space, they bring extensions, new windows or altered window openings, cladding and front vehicle hardstandings under planning control, and the leaflet also lists porches, boundary walls, gates and fences and exterior painting. Demolishing, building or altering a chimney stack needs permission too, but like-for-like repairs do not.

The Character, Sustainability and Design Codes SPD, adopted on 14 May 2024, supersedes the 2017 Residential Extension Guidelines. Its Part A5 gives maximum single-storey rear extension depths of 3.05m for a terraced house and 3.65m for a semi-detached one, measured from the original rear wall, says front dormers will generally be refused, opposes new basements to listed buildings in principle and asks you to read the individual appraisal alongside it. Part B10 adds a vision and neighbourhood guidance for Chiswick.

Access and site planning

Hounslow says Hounslow Highways issues the licences for temporary structures on roads, and that licences are needed for scaffolding, hoardings, building materials, crane operations and skips; an application without a current public liability insurance certificate and a full method statement will not be processed. The skip company applies for the skip permit, and no skip may stand on the footway or verge. For a skip in a parking bay, get the bay suspension approved first, applying at least ten working days ahead. On the Ealing side of Woodstock Road, ask Ealing Council.

Continue planning

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

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