Basement conversion in Chiswick

Investigate the structure and ground before design.

Start with the basement conversion brief

Distinguish an existing cellar conversion from excavation for a new basement. Record levels, drainage, access and the adjoining structures, and obtain project-specific ground and structural investigations before relying on a design or budget.

Plan temporary works, waterproofing, ventilation, escape and spoil removal as part of the same brief. Ask Hampstead Chartered Surveyors to assess party-wall matters and Hampstead Architecture & Planning to coordinate the design requirements. An area name alone does not establish ground conditions.

The local building context

Designated on 7 November 1968 and extended in 2001, the Strand on the Green Conservation Area is, in its appraisal’s words, essentially a half-kilometre curve of houses of irregular heights, sizes and colours fronting the Thames. The appraisal, adopted in October 2018, finds its interest in a tranquil waterside setting of fishermen’s cottages, boat builders’ sheds, public houses and maltings, joined by larger houses in the late eighteenth century, and the area also takes in modest Victorian and Edwardian terraces. It dates Ship Cottage, Grade II, to 1694, the oldest building on the Strand; Zoffany House is Grade II*.

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*.

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.

Three documents need more care. Planning Data records 3 September 2024 as the designation date of the Glebe Estate, though its appraisal of that month calls it a new proposed conservation area and describes its coherent terraces and wide roads as an early and significant expression of a Victorian working-class estate in west London. The council lists a Chiswick High Road appraisal as updated in January 2022, so ask the council about its current status before relying on it. Hounslow’s Bedford Park appraisal prints no date, and Ealing’s July 2020 update addendum and its later consultation are Ealing’s own documents, the consultation relating only to the western part of the estate that falls in Ealing.

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.

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The Chiswick area guide · Basement conversion across London · Hampstead Architecture & Planning · Hampstead Chartered Surveyors

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