Basement conversion in Hatch End

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

Harrow’s 2021 character study counts the Victorian semi-detached villas at Woodridings among Hatch End’s oldest development, and the 2011 assessment says initial suburban development there was dominated by Woodridings, an estate of Italianate villas along Uxbridge Road, Devonshire Road and Wellington Road. Around Wellington, Devonshire and Cornwall Roads it records a mix: one three-storey Italianate pair surviving on Wellington Road, Edwardian and inter-war detached houses, a 1930s mansion block, 1960s and 1970s flats and 1950s maisonettes in two-storey pairs, with some front gardens lost to hard surfacing and forecourt parking.

Inter-war growth brought the garden suburb of Pinnerwood Park, the Tudorbethan estate at Sherrington Avenue and Royston Park. Around The Avenue, Royston Park Road and Royston Grove, the 2011 assessment records mainly Edwardian, 1930s and post-war houses, usually two storeys plus rooms in the roof, many Arts and Crafts in style with tall chimneys and complex hipped and gabled roofs in brick, tile and render, set well back on wide streets with very large mature trees. Along Uxbridge Road it records mainly 1930s detached and some semi-detached houses, some with Tudorbethan bays and gables.

The Pinnerwood Park Estate, now a conservation area that Harrow lists with Pinner and its 2021 study names among Hatch End’s garden suburb estates, was laid out for the Artizans, Labourers and General Dwellings Company, and its layout was granted planning permission on 6 October 1932; only about 435 houses were built. Its 2009 appraisal describes two-storey cottage-style houses of dark red multicoloured brick with lighter red quoins, hipped roofs of handcut red plain tiles and tall chimneys, separated by hedges rather than walls, on streets with grass verges, granite kerbs and mature trees.

Local design and consent context

Harrow designated Pinnerwood Park Estate as a conservation area on 31 August 1989. Its current appraisal and management strategy, adopted in December 2009 as Appendix 8 to the Pinner Conservation Areas SPD, replaced a February 1990 appraisal and carries weight as a material planning consideration. Harrow lists the area on its Pinner page, its 2021 character study names it among Hatch End’s garden suburb estates, and the Pinner SPD says the Hatch End local centre lies outside the conservation area but forms part of its setting.

The conservation area is in two parts, and the appraisal lists its roads, several only in part, among them Uxbridge Road, Grimsdyke Road, Altham Road, Woodhall Drive and Pinner Hill Road, so check the house number as well as the street. It records hipped roofs turned into gables, large dormers and third front gables as eroding the area’s appearance, says new front dormers would be out of character and hip-to-gable conversion is unlikely to be permitted, finds conservation rooflights only likely to be acceptable at the rear, and asks extensions not to overpower the house or offset the symmetry of paired houses.

In the core area, planning permission is needed for additions and alterations, including replacing windows and doors other than at the rear, dormers, rooflights and the gabling of hipped roofs, porches to front or side doors, hard surfaces and boundaries in front and side gardens, and painting unpainted surfaces. In the outer areas, the same kinds of work need permission only on elevations facing a highway, waterway or open space. The 2009 schedules place 516 to 530 Uxbridge Road, except 522, in the core area and Grimsdyke Road from 35 to 67 (odd) and 40 to 82 (even) in the outer areas; confirm the house number with Harrow.

Access and site planning

Harrow permits noisy construction work from 8am to 6pm, Monday to Friday, and 8am to 1pm on Saturday, with none on Sundays or bank holidays. It can limit working hours under the Control of Pollution Act 1974 and suggests warning neighbours in advance about the work and how long it will last. In a flat or maisonette, ask the managing agent about building rules on hours, deliveries and common parts; if you stay at home, agree which rooms stay in use and when water or power will be off.

Continue planning

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

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