House extension in Cockfosters

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

Along Cockfosters Road, the appraisal records Cockfosters Cottages, built in the 19th century for the Bevans of Trent Park to house estate workers. It dates Nos. 337–345, a red-brick terrace with small-paned sashes, to about 1800–20; Nos. 325–335 are a grade II listed Tudor revival group of 1837–1840 in yellow stock brick with four-centred arched porches; and Nos. 305–319 are a late-Victorian terrace with unusual triangular dormers. It finds a degree of unity in their consistent scale, eaves lines and brick and slate on low-pitched roofs, with small front gardens and picket fences softening them.

Around the Chalk Lane cricket ground, the appraisal finds formally arranged suburban housing on three sides, and calls Christ Church, built in 1839 of stock brick, an important local landmark whose spire is highly visible, particularly from the Underground station. Across the boundary, Barnet’s 2007 Monken Hadley appraisal describes Games Road with housing on one side only, set back behind greens, including Nos. 10 to 18, a terrace of modest cottages built in 1750. It records Ludgrove Hall, of the 1830s, and West Farm Court as converted into apartments, and The Grange as a modern block of neo-Georgian flats.

Neither the name Cockfosters nor an EN4 postcode settles which council decides, whether a home is in a conservation area or listed, which Article 4 direction applies or which consent route the work takes. Enfield’s Cockfosters ward also takes in Hadley Wood, Barnet uses the name for streets in its East Barnet ward, Heddon Court Avenue appears in both councils’ records, and Enfield’s own records list some Enfield properties with a ‘Barnet’ postal address. Confirm the council with the official lookup using the full postcode, not EN4 alone; Barnet notes that postcodes do not match administrative boundaries exactly. If in doubt, ask the council. Then read that council’s conservation map, the list entry, the Article 4 schedule or mapped area, the title or lease and the planning history of the property.

Local design and consent context

Trent Park, reference CA18, is one of Enfield’s 22 conservation areas and is separate from the Hadley Wood Conservation Area. It was designated in 1973 and extended to include Cockfosters Cottages in 1990 and the area around Chalk Lane in 1993. Its character appraisal, first adopted in 2006 and reviewed in February and March 2013, was approved in February 2015, with separate management proposals. It describes five character areas, including Cockfosters Cottages and Chalk Lane with the cricket ground, and roughly eighty residential addresses, and says about half of the conservation area is on the register of parks and gardens at grade II.

The appraisal says designation brings a general control over the demolition of unlisted buildings and over lopping or felling trees above a certain size, while some changes to family houses do not normally need planning permission and an Article 4 direction can withdraw particular permitted development rights. The management proposals say development affecting listed or locally listed buildings, buildings identified as making a positive contribution, or buildings affecting their setting, should normally use matching traditional historic materials and detailing, and that mass-produced materials such as uPVC and concrete roof tiles will not normally be appropriate within the conservation area.

Across the boundary, Barnet’s Monken Hadley Conservation Area was designated in December 1968 as one of the first four in the borough, and its character appraisal was adopted in January 2007. Barnet’s boundary map, dated November 2023, gives its last amendment as 15 January 2007. The boundary takes in the part of the former Trent Park West conservation area that lies in Barnet, the rest being in Enfield, and the appraisal says the greater part of the conservation area is covered by Green Belt.

Access and site planning

For an Enfield address, the council says noisy building work that can be heard at the site boundary should only take place Monday to Friday, 8am to 6pm, and Saturday, 8am to 1pm, and is not allowed outside these times or on bank holidays unless agreed with the council in advance. For a Barnet address, Barnet’s published hours are Monday to Friday, 8am to 6pm, and Saturday, 8am to 1pm, and at no time on a Sunday or bank holiday. A lease or building manager may set tighter limits. If you will live at home through the work, decide which rooms stay usable and when water or power will be off, and tell neighbours what is planned and when.

Continue planning

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

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