296 Council Policies That Affect Your Extension

What Councils Actually Control

The General Permitted Development Order (GPDO) grants rights nationally, but councils have several mechanisms to restrict or modify them locally:

• 1.Conservation area designations. Properties inside a conservation area lose permitted development rights for side extensions, cladding, and rear extensions visible from a public highway. The council designates these areas and reviews them periodically.
• 2.Article 4 directions. Councils can remove specific permitted development rights for defined areas. These are common in conservation areas but can also apply to individual streets or even single properties. Article 4 directions must be formally made and registered.
• 3.Supplementary Planning Documents (SPDs). SPDs provide detailed guidance on how a council interprets and applies planning policy. An SPD on residential extensions will typically cover materials, design, neighbour impact, and what the council considers acceptable. SPDs are not law, but planning officers use them to assess applications.
• 4.Local Plan policies. Each council has a Local Plan (or equivalent development plan documents) that sets the strategic framework. Policies like “protect residential amenity” or “respect local character” are interpreted by planning officers when deciding applications.
• 5.Conditions on original planning permission. Some properties — particularly those built after 1948 — may have conditions attached to the original planning permission that remove or restrict PD rights. These are property-specific and not always obvious from planning portal searches.

How to Find Your Council's Extension Policy

Finding the right policy document is harder than it should be. Council websites are notoriously difficult to navigate, and extension guidance can live under “Planning Policy,” “Building Control,” “Householder Extensions,” or “Design Guidance” depending on how the site is structured.

Here is the most reliable approach:

• 1.Search “[council name] householder extensions SPD” in Google. This will often surface the specific supplementary planning document directly, bypassing the council's navigation.
• 2.Check the planning policy page. Most councils have a “Planning Policy” or “Local Plan” section that lists adopted SPDs. Look for documents titled “Residential Extensions and Alterations,” “Householder Design Guide,” or “Residential Design Standards.”
• 3.Look for a pre-application advice service. Many councils offer a paid pre-application service (typically £150-500) where a planning officer will review your proposals informally before you submit. This is the most reliable way to understand local interpretation of policy.
• 4.Search the planning portal for similar nearby projects. Find approved applications for extensions on your street or in your area. This gives you direct evidence of what the council has accepted recently — far more useful than reading policy in the abstract.

All 33 London Boroughs: Planning Portal Reference

Every London borough uses an IDOX-based planning portal for submitting and tracking planning applications. This table lists all 33 boroughs for quick reference.

Planning Portal Types Explained

Across England, councils use several different planning portal systems to manage applications. Understanding which system your council uses helps when searching for application history and tracking decisions.

• 1.IDOX (Uniform/Public Access). The dominant system, used by the vast majority of London boroughs and many councils across England. Recognisable by its “Public Access” URL pattern. Provides searchable application databases with documents, constraints maps, and decision notices.
• 2.Planning Portal (national). The centralised national system at planningportal.co.uk. All councils accept applications through this system, but the local search and tracking portals vary. Applications submitted via the national portal are routed to the local system.
• 3.Agile Applications / NEC. Used by some councils outside London. Similar search functionality to IDOX but with a different interface. More common in county councils and district councils in the Midlands and North.
• 4.Northgate / MasterGov. Legacy systems still in use at some smaller councils. Generally being phased out in favour of IDOX or cloud-based alternatives.

Supplementary Planning Documents: What They Mean for Your Extension

SPDs are the single most important council-level documents for extension projects. They bridge the gap between broad Local Plan policies and the specific decisions planning officers make on individual applications.

A typical householder extensions SPD will cover:

• -Maximum depths and heights for single and two-storey rear extensions, often more restrictive than national PD limits
• -45-degree and 25-degree rules for assessing impact on neighbouring properties' daylight and sunlight
• -Material matching requirements - some councils insist on matching existing brickwork; others are more flexible with contemporary materials
• -Roof form guidance - pitched vs flat roofs, parapet walls, and acceptable roof lantern designs
• -Minimum garden depth after extension, which can be the binding constraint on deep rear extensions
• -Loft conversion guidance including dormer proportions, set-back from eaves, and ridge height restrictions

SPDs are “material considerations” in planning decisions, meaning officers must take them into account. However, they do not have the same legal weight as Local Plan policies. An application that departs from SPD guidance can still be approved if there are good reasons.

The 296 Councils Dataset

England has 296 local planning authorities: 33 London boroughs, 36 metropolitan boroughs, 181 district councils, 25 county councils with planning functions, and 21 unitary authorities. Each one maintains its own planning policies, constraint maps, and application databases.

Of these 296 councils, we were able to discover active, publicly accessible policy pages for 178 (60%). The remaining 118 either have policy documents buried deep within their websites, host guidance as downloadable PDFs without dedicated landing pages, or have outdated or broken links.

Discovery rate reflects councils with publicly accessible web pages specifically addressing householder extension policy. All 296 councils have planning policy documents; not all are easily discoverable online.

Practical Tips for Navigating Council Policy

• 1.Start with your constraints, not the policy. Before reading SPDs, check whether your property is in a conservation area, has Article 4 directions, or is listed. These binary checks determine whether permitted development applies at all. Our free AI chat does this instantly.
• 2.Search for approved examples on your street. The IDOX portal for your borough lets you search by postcode or address. Find approved extension applications nearby to see what the council has accepted. This is more reliable than interpreting policy wording.
• 3.Consider pre-application advice. At £150-500, it is the cheapest insurance against a refused application. The planning officer will tell you informally what they would and would not accept. This is especially valuable in conservation areas or boroughs with strict design policies.
• 4.Check the adoption date of the SPD. SPDs adopted before 2019 may not reflect the latest permitted development changes (like the extended PD rights for larger rear extensions). A 2014 SPD may describe rules that have since been liberalised nationally.
• 5.Remember: PD does not need council approval. If your extension falls within permitted development limits and your property has no constraints removing PD rights, you do not need planning permission. A Lawful Development Certificate (LDC) provides legal proof but is optional. The council's SPD is only relevant if you need planning permission.

When National Rules Override Local Policy

Permitted development rights are granted by national legislation (the GPDO), not by councils. A council cannot refuse to allow a development that falls within PD rights unless it has formally removed those rights through an Article 4 direction or the property is in a designated area (conservation area, AONB, National Park, etc.).

This means that an SPD saying “we do not support flat-roofed rear extensions” has no legal effect on a PD-compliant extension. It only applies when you need planning permission. Many homeowners — and even some architects — confuse SPD guidance with PD limits. They are separate frameworks.

The key exceptions where local policy overrides national PD rights:

• -Properties in conservation areas (restricted PD for side extensions, cladding, chimneys)
• -Properties subject to Article 4 directions (can remove any or all PD rights)
• -Listed buildings (all external changes require listed building consent)
• -Properties with conditions on original planning permission removing PD rights
• -Properties in AONBs, National Parks, the Broads, and World Heritage Sites

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