What a conservation area is
A conservation area is a designated area of special architectural or historic interest, the character of which it is desirable to preserve or enhance. Conservation areas are designated by local planning authorities under section 69 of the Planning (Listed Buildings and Conservation Areas) Act 1990. There are over 1,000 conservation areas in London, covering roughly 25% of residential land. Examples: most of Belsize Park, much of Hampstead, most of Stoke Newington, large parts of Camberwell, most of Greenwich. Whether your property sits in a conservation area is recorded on the borough's online planning map.
What's restricted in a conservation area
Conservation area designation adds restrictions to permitted development rights and additional controls on works that would otherwise be unregulated. Side extensions require planning permission (PD is removed). Roof extensions (including loft dormers) usually require planning. Demolition of any building over 115m³ requires planning permission (Conservation Area Consent was abolished but the requirement was rolled into planning permission). Painting of previously unpainted brickwork is restricted. Removal of trees over a certain trunk size requires notice to the council. Replacement of windows and doors to materials or styles incongruous with the area is restricted. Each borough also operates an Article 4 direction that may add further restrictions specific to that conservation area.
Working with the design context
Successful conservation area applications work with the historic context rather than against it. Planning officers look for proposals that preserve or enhance the character — using sympathetic materials, proportions, and detailing. Common acceptable approaches: rear extensions with matching brick, slim-frame glazing, lead or zinc roof details. Common refusals: large-volume modern flat-roofed glass boxes that contrast violently with the period stock. The judgement isn't 'no modern interventions allowed' — it's 'modern interventions that respect the host building'. We work with conservation-specialist architects on every conservation area project to design submissions that maximise the chance of approval.
Materials and detailing requirements
Conservation area planning usually specifies external materials. Brick: matching the existing in colour, size and bond — usually requires London Stock Yellow on Victorian terraces, or hand-made brick to specific size and texture for Georgian buildings. Render: matching colour and finish; sand-faced or smooth as the existing. Glazing: slim-frame sash or casement windows in painted timber or steel; aluminium powder-coat in a sympathetic colour is often acceptable; PVC is almost always refused. Roof: natural slate or clay tile matching the existing; no concrete tiles, no metal roofing on visible elevations. Detailing: traditional cornices, sills, headers, brick arches, lead flashings. The cost premium for conservation-compliant materials and detailing is typically 15–25% over baseline construction.
What still works under permitted development
Even in a conservation area, some permitted development rights survive. Single-storey rear extensions under the size limits remain PD (subject to any specific Article 4). Internal alterations not affecting external appearance remain unregulated. Outbuildings within the size and location limits remain PD. Repairs and like-for-like maintenance remain unregulated. We run a free desktop check to confirm what is and isn't allowed at your specific address — conservation areas vary enormously, and a single check often reveals more PD potential than expected.
Timeline and approval rates
Conservation area planning applications in London typically take 8–10 weeks for determination plus 4–8 weeks for pre-application discussion (which we recommend on all conservation area projects — pre-app comments shape the design before formal submission and dramatically improve approval rates). Our approval rate on conservation area first-time submissions is 81% over the past three years, against a London average of 58%. The difference: we don't submit applications we don't think will succeed — we resolve issues at pre-application and design phase rather than risk a refusal that creates a presumption of unacceptable impact for any future application.
