Basement conversion in Blackheath

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

Royal Greenwich designated the Blackheath Park conservation area in 2002, when a boundary review split the original Blackheath area in two. Its appraisal, which the council lists as 2013, places the private Cator Estate within it: wide tree-lined avenues, villas set back from the road, grass verges, gutters of granite setts and white-painted timber gates at the entrances. The area also takes in the east side of Blackheath Village from the railway to Cresswell Park, 1–23 Lee Road, Cresswell Park and Bennett Park.

The appraisal finds the area’s significance in the quality and diversity of its housing, from grand Georgian and Victorian villas to compact flats. Pond Road has listed 1830s Regency stucco villas and, beyond the church, four 1860s villas; Morden Road, laid out in 1852–3, has large yellow-brick villas, some divided into flats by the 1930s. Between 1958 and 1969 Span replaced eight houses with 240 houses and 181 flats; its hallmark was the short terrace, often grouped round a courtyard or set among shared gardens. Cator Estate South has two-storey brick houses of the 1930s.

Beside it lies Royal Greenwich’s Blackheath conservation area, designated in 1968, which covers the streets east of the Heath between Kidbrooke, Maze Hill and Blackheath Park and was substantially complete by 1900. Its set pieces include Morden College, a charitable foundation of 1695, and the Paragon, four-storey paired villas linked by colonnades, built on one of the first Cator leases. Its appraisal records homes from modern purpose-built flats to substantial mansions, and says many of the mansions have been subdivided. It gives Welsh slate as the prevailing roof, with widespread replacements in concrete tiles and artificial slate.

Local design and consent context

The council’s conservation page lists a Blackheath Park conservation area appraisal, with photo surveys and a boundary map, and a Blackheath appraisal in four parts with its own boundary map, both labelled 2013. Their text was written before summer 2010 and the photo surveys date their fieldwork to 2006, so treat them as the council’s appraisals listed as 2013 rather than recent studies. Each describes itself as a non-statutory planning document to be read with national, regional and local planning policy.

The council’s 2010 management guidance covers the Greenwich and Blackheath conservation areas together. It says further backland development in Blackheath Park should be permitted only in the most exceptional circumstances. It names ill-considered attic conversions in the inter-war area, and the loss of front gardens to hard standing along Lee Road, as risks. It also records that the north-western part of the Blackheath area, from Stratheden Road to Westcombe Park Road, lay within the Maritime Greenwich World Heritage Site buffer zone, and that Blackheath Park did not.

Royal Greenwich’s development plan is the London Plan 2021, the Core Strategy with Detailed Policies, adopted on 30 July 2014, and, where relevant, the Lee Neighbourhood Plan 2024. Policy DH(h) grants permission in a conservation area only for proposals that pay special attention to preserving or enhancing its character or appearance, and DH(a) limits rear, side and other additions, basements included, to a scale and design suited to the building and locality. The Urban Design Guide supplementary planning document, adopted on 18 October 2023, is consistent with the Core Strategy.

Access and site planning

On Royal Greenwich streets, a skip on the road needs a licence that only a skip hire company can obtain, usually valid for 30 days, while a skip in a front garden or driveway needs none. Scaffolding and hoardings on a public street or pavement need licences, as do building materials left there, and parking bay suspensions should be applied for 10 working days ahead. The Blackheath Park appraisal records that only Lee Road, Bennett Park and Cresswell Park are public roads there, so on an estate road ask who controls it before booking. On the Lewisham side, a skip on the highway needs a licence, and scaffolding or hoarding licences are requested at least five days ahead.

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

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