House extension in High Barnet and Monken Hadley

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

Barnet’s Monken Hadley Conservation Area Character Appraisal Statement, adopted in January 2007, describes an area that is still green, leafy and of low built density, with large Georgian houses and gardens around Hadley Green and the edges of the Common. Small Victorian cottages of stock brick or stucco line the road at Hadley Highstone, Hadley Green Road has a string of mainly Georgian listed buildings and Dury Road a range of listed buildings, several timber-framed. Hadley Grove has a group of Edwardian houses, and the High Street end is tighter, commercial and mostly Victorian.

Barnet’s Wood Street appraisal of July 2007 describes a conservation area running west along the ridge from St John the Baptist church at the top of Barnet Hill, taking in historic shops, Union Street, the villas facing Ravenscroft Park and Wood Street as far as The Whalebones. It records Victorian villas and terraces, almshouses, 18th and 19th-century houses and timber-framed buildings refronted in brick or stucco, with large central chimneystacks and clay-tiled roofs, such as 32 and 17 Wood Street. The land drops south of Wood Street towards the Dollis Brook, on ground the appraisal describes as largely London clay.

Neither the names High Barnet and Monken Hadley nor an EN5 postcode tells you which council decides, whether a home is in the Monken Hadley or Wood Street Conservation Area or the Green Belt, whether it is listed, which Article 4 direction applies or which consent route the work takes. The Monken Hadley Conservation Area has Hertfordshire and Enfield on its northern boundary, and a 2019 Barnet tree preservation order still gives an EN5 address on Wood Street as Barnet, Hertfordshire, so confirm the council with the official lookup, then read the conservation area map, the list entry, the mapped Article 4 areas, the title or lease and the planning history of the property itself.

Local design and consent context

Monken Hadley (CA01) was designated in December 1968, one of Barnet’s first four conservation areas, and extended in February 1979 to the northern end of Chipping Barnet High Street. Barnet’s map, dated November 2023, gives its last amendment as 15 January 2007 and marks the borough boundary. The Character Appraisal Statement, adopted in January 2007 with a management plan, divides the area into ten sub-areas, from Hadley Highstone and Hadley Green to Barnet High Street, Camlet Way and Monken Hadley Common. Its guidance says extensions should normally be subordinate to the main building and need thoughtful design at the rear as well as the front, and that materials should match the existing building unless a contrast is intended.

Wood Street’s direction, A4D13, records approvals in 1970, 1974 and 1981, and Planning Data maps it as two areas. The appraisal says it covers most of the conservation area and brings replacement windows and doors, roof extensions and rooflights, new wall materials and painting, small extensions such as front porches, outbuildings, oil tanks, satellite dishes, the removal and replacement of boundaries other than hedges, front-garden hard standings and crossovers, and most new gates, fences and walls under planning control. In 2007 Barnet removed it from 2 to 30 (even) West End Lane, The Croft in Blenheim Road and 6 and 8 Queens Road.

The Monken Hadley appraisal records about three quarters of the conservation area as Green Belt and over half of it as open fields and recreational land, and a Planning Data search finds the current Barnet Green Belt record, part of the London Green Belt, overlapping it but none in Wood Street. Green Belt is a separate designation from the conservation area, with its own national policy test. Check with Barnet whether the Green Belt boundary takes in your house or garden.

Access and site planning

Barnet’s 2007 Wood Street appraisal describes traffic dominating the High Street end, busy and noisy particularly at the junction of Wood Street with High Street; it also records busy traffic in the morning and afternoon rush hours on Wood Street between Tudor Hall and the Black Horse, and limited parking schemes in the area. The Monken Hadley appraisal records restricted road widths around Taylors Lane and Old Fold Lane, describes Camlet Way as a narrow lane and notes that Games Road has no pavement or kerb. A skip on a public road needs a council licence, usually obtained by the skip company, while one wholly on private land needs none; scaffolding or hoarding on the highway needs a licence too. TfL licenses such items only on its red routes, so check whether the road outside is one.

Continue planning

The High Barnet and Monken Hadley area guide · House extension across London · Hampstead Architecture & Planning · Hampstead Chartered Surveyors

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