Loft conversion in Mill Hill

Test the roof space before settling on a layout.

Start with the loft conversion brief

A measured roof survey should establish headroom, structural spans and where a staircase could meet the floor below. Plan the stair, escape route, insulation and building services together before treating the loft as another room.

Compare the proposed roof shape with the address-specific design guidance below. Record chimneys, shared walls and neighbouring rooflines, then ask the appointed designers to identify the structural work and consents the proposal needs.

The local building context

The appraisal’s principal building types include timber-framed buildings from the late sixteenth century onwards, largely remodelled in brick or white or black weatherboard, with clay-tiled roofs, timber casements or sashes and low picket fences; Rosebank and Rosebank Cottage on The Ridgeway, a seventeenth-century timber-framed building, is listed at grade II. Small weatherboard and brick cottages of the mid-eighteenth to nineteenth century are another, such as the late eighteenth-century weatherboarded cottages on Hammers Lane, also grade II. Early timber-framed roofs are pitched at about 45 degrees in handmade clay tiles; most buildings after the mid-nineteenth century have Welsh slate.

Mill Hill Village, a cluster of small vernacular dwellings at the top of Milespit Hill, is mainly two-storey late Victorian development in brick under slate or tile, or render under tile, behind white-painted picket fences. Wills Grove and Winterstoke Gardens have early twentieth-century Arts and Crafts houses in red brick and tile, with roughcast or brick walls, steep roofs, timber casements, prominent chimneys and hedged boundaries. By 2008 some former Mill Hill School boarding and staff houses on Wills Grove were private houses and apartments, and the appraisal records John Laing’s 1933 Sunnyfields Estate where Lawrence Street meets Highwood Hill.

The council, the conservation boundary, any listing and the consent route all depend on the exact property; the name Mill Hill and an NW7 postcode answer none of them. Use the government’s council lookup first; after that, work through the conservation area boundary map, the listed building records, the Article 4 orders and the January 1991 schedule of properties, the title or lease and the planning history of the property. The 2008 appraisal proposed taking one Marsh Lane house out of the boundary, so rely on the current map rather than older plans.

Local design and consent context

According to the 2008 appraisal, an Article 4 direction made shortly after designation covers most of the conservation area. In the parts it names, around the Old Forge, The Ridgeway, Milespit Hill, Wills Grove and Winterstoke Gardens, it lists planning controls including replacement windows and doors, roof lights, new wall materials and painting, small additions such as front porches and outbuildings, replacing boundaries other than hedges, hardstandings in front gardens, vehicle crossovers, and most new gates, fences and walls.

A separate Article 4(2) direction, whose map outlines the Retail Trust Cottages on both sides of Hammers Lane, controls specified householder works that would front a highway, waterway or open space, and the erection, alteration or removal of chimneys. The order is marked approved on 24 April 2008, but planning data starts it on 15 January 2007, so confirm the details with Barnet. Mill Hill Cemetery has a direction of its own covering gates, fences, walls and other means of enclosure.

Green Belt is a different designation from the conservation area. The 2008 appraisal records the green open space within and around the conservation area as Green Belt, open land where development is strictly controlled to prevent urban sprawl, and planning data holds a current Green Belt record for Barnet. Ask Barnet whether land at the address lies in the Green Belt today, and treat that as a separate question from the conservation-area and Article 4 controls.

Access and site planning

Delivery stops, waste storage and protection for any shared hall, stair or drive all need a plan before work starts. Barnet’s 2008 appraisal describes The Ridgeway and Highwood Hill as busy vehicular routes, with heavy school traffic on The Ridgeway, Wills Grove as a private shared-surface road with patchy, privately maintained surfacing, and Wills Grove and Winterstoke Gardens as informal roads with no pedestrian paths. Before scaffolding, a skip or materials go on the road or pavement, ask the highway authority which licence is needed and how much notice it requires; TfL issues such licences only on its red routes, so check whether the road outside is one.

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The Mill Hill area guide · Loft conversion across London · Hampstead Architecture & Planning · Hampstead Chartered Surveyors

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