Conservation Areas in London: Planning Rules, Permitted Development Restrictions, and What You Can and Cannot Build

**What a conservation area is**:

A conservation area is an area of special architectural or historic interest, the character or appearance of which it is desirable to preserve or enhance, designated under Section 69 of the Planning (Listed Buildings and Conservation Areas) Act 1990 (LBCAA 1990). The designation is made by the local planning authority (the London Borough).

Conservation area designation does NOT mean that individual buildings are listed — and it does NOT mean that no change is possible. It means that the LPA has a statutory duty to preserve or enhance the character and appearance of the area when determining planning applications, and that certain types of development that would otherwise be permitted development require planning permission.

**How to find out if your London property is in a conservation area**:

1. The London Borough's planning portal: search the property address on the LPA's online planning map; conservation areas are shown as a shaded overlay 2. Historic England's listed building and conservation area map at historicengland.org.uk 3. Magic Map Application (Magic.defra.gov.uk) — a government GIS mapping tool that shows conservation area boundaries 4. The property's Land Registry title register may note conservation area status in the title absolute entry, but this is not guaranteed

**How conservation area designation affects permitted development rights — Article 4 Directions**:

Within a conservation area, the Secretary of State's permitted development rights (under the GPDO 2015) are modified by two mechanisms:

• *1. Conservation area conditions within the GPDO 2015 itself*:
• Several Part 1 permitted development rights (which allow residential alterations without planning permission) contain specific conditions that do not apply outside conservation areas:
• •Class A (extensions and outbuildings): extensions are still permitted development in a conservation area up to the standard PD limits (side return extension: PD depth 3m semi/4m detached; no Class A extensions on side elevation visible from highway; rear extension height limits), BUT any extension on the front elevation is more restricted
• •Class C (roof alterations): roof windows that would materially alter the external appearance of the principal elevation are NOT permitted development in a conservation area (all Velux windows on the front roof slope require planning permission in a conservation area)
• •Class D (porches): porches on the principal elevation in a conservation area require planning permission (Class D PD right does not apply in conservation areas)
• •Class E (outbuildings, garages, swimming pools, oil tanks, etc.): outbuildings and garages in the curtilage of the dwellinghouse are NOT permitted development in a conservation area if they are to be built between the side elevation of the house and the highway boundary, or if they are to be built on land forward of the principal elevation
• •Class G (solar panels): the installation of solar panels on the principal (front) elevation or the side elevation visible from the highway is NOT permitted development in a conservation area

• *2. Article 4 Directions made by the London Borough*:
• In addition to the GPDO 2015 conservation area conditions above, most London Boroughs have made Article 4 Directions within their conservation areas that withdraw ADDITIONAL permitted development rights beyond those already restricted by the GPDO 2015 itself. Common additional PD rights withdrawn by Article 4 Directions in London conservation areas include:
• •Class B (roof enlargements — dormers): as described in `planning-permitted-development-loft-guide`, most London conservation areas have Article 4 Directions withdrawing Class B PD rights — requiring planning permission for all dormers
• •Class A (extensions): some London conservation areas have Article 4 Directions withdrawing Class A PD rights entirely, requiring planning permission for all extensions including those to the rear
• •Front elevation changes: changes to windows, doors, or external materials on the front elevation

The scope of the Article 4 Direction varies by conservation area and by Borough — always check the specific Article 4 Direction for the specific property rather than assuming all conservation areas have the same restrictions.

**Trees in London conservation areas — the 6-week notification rule**:

This is one of the most commonly overlooked planning obligations in London conservation areas. Under Section 211 of the TCPA 1990, any person wishing to carry out work on a tree in a conservation area must give the LPA at least **6 weeks' written notice** before commencing the work — unless the tree is already subject to a Tree Preservation Order (in which case a formal application for consent is required and the 6-week notice route does not apply).

• *Which trees does Section 211 apply to in a conservation area*:
• •ANY tree in a conservation area — regardless of size, species, age, or condition
• •There is no minimum trunk diameter or canopy size threshold for the Section 211 notification requirement — even a small garden tree (20–30cm diameter) requires 6 weeks' prior notification if it is in a conservation area

• *What constitutes 'work on a tree' for Section 211 purposes*:
• •Felling (cutting down the tree)
• •Pruning (cutting any branch of the tree)
• •Lopping (cutting branches or roots to reduce height or spread)
• •Topping (removing the leading shoot or upper branches)
• •Any other works that cut or damage the root system (excavation within root protection area; construction works that sever roots)

• *The 6-week notice period*:
• •Submit a written notification to the London Borough's planning/tree officer
• •The 6-week period runs from the date the LPA receives the notification
• •During the 6-week period, the LPA can:
• - Make a Tree Preservation Order (TPO) on the tree — this requires a formal consent application before any work can proceed
• - Approve the works (expressly or by not responding within 6 weeks)
• - Request additional information about the proposed works and justification
• •If no TPO is made within 6 weeks, the work may proceed

*Carrying out works to a tree in a conservation area without prior notification is a criminal offence under Section 210 TCPA 1990, punishable by a fine of up to £20,000 or an unlimited fine on Crown Court conviction.*

• *Exemptions from Section 211 notification*:
• •Trees with a trunk diameter of less than 75mm at 1.5m height (approximately 25cm circumference) are exempt — effectively trees with a trunk smaller than a fist
• •Dead trees
• •Trees that are imminently dangerous (requiring emergency work to prevent immediate risk to persons or property — but proof of imminence is required)
• •Fruit trees in commercial orchard use

**Demolition in conservation areas**:

• Section 196D of the TCPA 1990 (as amended in 2013, following the abolition of Conservation Area Consent) requires planning permission for the demolition of a building in a conservation area where the building exceeds a certain size threshold:
• •Buildings with a cubic content exceeding 115m³ (measured externally): require planning permission for demolition in a conservation area
• •Walls, gates, fences, and other structures: require planning permission for demolition in a conservation area if the structure is within the curtilage of a listed building, or if the wall is over 1m high adjoining a highway or public open space, or over 2m high elsewhere

*Conservation Area Consent (CAC) was abolished on 1 October 2013* — it has been replaced by the full planning permission requirement under Section 196D. Applications for planning permission for demolition in a conservation area are assessed against the policies in the National Planning Policy Framework (NPPF) and the relevant London Borough's Local Plan policies on heritage and conservation.

**Material change of use in a conservation area**:

Conservation area designation does not by itself remove permitted development rights for material changes of use — these are governed by the GPDO 2015 (Use Classes Order) which applies equally inside and outside conservation areas. However, where a change of use has planning implications for the appearance of the building or the character of the area (e.g., converting a house to multiple flats, which often involves external alterations), the conservation area context is a material consideration in the planning assessment.

**What is a Conservation Area Character Appraisal**:

• A Conservation Area Character Appraisal (also called a Conservation Area Appraisal or Management Plan) is a document prepared by the London Borough that:
• •Identifies the boundaries of the conservation area
• •Describes the special architectural and historic interest that justified designation
• •Characterises the area in terms of: building heights and typologies; building materials (brick type; mortar; slate species; window styles); street widths and patterns; trees and landscaping; land uses; plot sizes and boundary treatments
• •Identifies positive and negative features within the conservation area (buildings that enhance or detract from the character; unlisted heritage assets of significance; key views and vistas)
• •Sets out Management Plan guidelines for how the LPA will assess future development proposals

The Character Appraisal is the primary planning policy document for assessing development proposals in the conservation area. A planning application for an extension or loft conversion in a London conservation area will be assessed principally against the policies in the Character Appraisal — a well-prepared Design and Access Statement (see `design-and-access-statement-guide`) must directly reference and respond to the relevant Character Appraisal.

• *How to find your conservation area's Character Appraisal*:
• •Search for '[London Borough] conservation area character appraisal [conservation area name]' on the Borough's planning policy web pages
• •Request a copy from the Borough's conservation officer via the planning team
• •Character Appraisals are public documents; they are often downloadable as PDFs from the Borough's website

**Common design requirements for extensions in London conservation areas**:

While the specific requirements vary by conservation area and by Borough, the following design standards are commonly applied across London conservation areas:

• *Materials*:
• •Matching or complementary brick: where the existing building is London stock brick (yellow; yellow-brown; buff), the extension should use matching or reclaimed stock brick of similar colour and texture
• •Lime mortar: many London conservation area guidance documents specify lime mortar pointing rather than modern cement mortar in extensions adjacent to or attached to Victorian brick walls
• •Roof materials: slate (natural Welsh slate or synthetic slate of similar appearance); clay plain tile where period appropriate; flat roofs only where contemporary design is otherwise accepted; lead flashing at junctions
• •Windows: timber sash (or high-quality aluminium sash where the Borough accepts aluminium as a conservation area appropriate material); double glazed; matching the existing window proportions
• •No UPVC windows or doors on any elevation visible from a public highway in almost all London conservation areas

• *Extensions*:
• •Single-storey rear extensions: typically accepted in most London conservation areas provided they are subservient to the host building (lower ridge line; setback from the side return; matching or complementary materials)
• •Double-storey rear extensions: more contentious; assessed for overshadowing and massing impact on neighbours; typically require a stronger design justification
• •Side return infill extensions: common in London Victorian terraces; typically accepted at ground floor level; less certain at upper floor level where overlooking is a concern

• *Loft conversions and dormers in conservation areas*:
• •Dormer position: setback from the party wall by minimum 300mm–500mm (varies by Borough); setback from the ridge
• •Dormer cheeks: lead or zinc clad; slate to match the main roof; NOT render or UPVC
• •Dormer face: vertical sliding sash windows; traditional proportions; matching the existing window style
• •Mansard dormers: sometimes permitted where they reflect the prevailing character of the conservation area (more common in certain London Boroughs — Westminster, Kensington, Chelsea — where mansard dormers are part of the historic character)

**Enforcement in London conservation areas**:

• Planning enforcement in conservation areas is taken more seriously by London Boroughs than in non-designated areas. Unauthorised development in a conservation area (e.g., a dormer built without planning permission where Article 4 PD rights have been withdrawn) is subject to:
• •Enforcement notice requiring removal of the unauthorised development
• •Prosecution if the enforcement notice is not complied with
• •The 4-year enforcement immunity period does NOT apply to listed building enforcement (Listed Building Enforcement Notices can be served at any time); the standard 4-year period applies to operational development in conservation areas, but London Boroughs actively monitor for unauthorised development