How to Improve Your Planning Application — Tips for London Homeowners

Every London borough has a Local Plan that sets out planning policy for that area. Before you design anything, read the relevant section of your borough's Local Plan. For most homeowners, the key documents are:

• The Development Management Policies document (or equivalent)
• Any Supplementary Planning Documents (SPDs) for residential extensions
• Design guides specific to your area
• Conservation area appraisals if your property is in a conservation area

These documents tell you what the planners consider acceptable. Designing to these guidelines dramatically increases approval chances.

Most London boroughs also publish a design guide or character appraisal document. These typically include:

• Maximum extension depths and heights for different property types
• Preferred materials and finishes
• Guidance on window sizes and positions
• Rules about side extensions and their relationship to the street

Pre-application advice (pre-app) is a paid service offered by most London planning authorities where you submit a proposal and receive an officer's informal view before making a formal application.

Benefits of pre-app:

• Identify major concerns before you invest in a full application
• Get an officer's view on specific design questions
• Build a positive relationship with the planning department
• Reduce the risk of refusal or conditions that limit the scheme

Pre-app typically costs £200–£600 for a householder application. For a project costing £80,000–£200,000, this is excellent value.

Not all pre-apps are equally useful — a well-prepared submission with specific questions gets better responses than a vague enquiry.

Planning officers consistently prefer proposals that respect the character of the local area. For London Victorian terraces, this typically means:

• Materials that match or complement the existing house (London stock brick, white render, zinc for flat roofs)
• Roof forms that reflect the local vernacular
• Window proportions consistent with the street
• Avoiding over-dominant rear extensions that would significantly overshadow neighbours
• Respecting the established building line

The biggest planning risk for extensions is trying to do too much relative to what the neighbouring properties show. If the entire street has 3m rear extensions, a 6m extension is harder to justify.

Planning officers assess extensions against neighbour impact criteria:

Daylight and sunlight: Extensions must not materially reduce the daylight and sunlight received by neighbouring properties. The most commonly used test is the 45-degree rule: if the extension does not cross a line drawn at 45 degrees from the nearest window of the neighbouring property (in plan and section), it is generally considered acceptable.

Overlooking and privacy: New windows must not create unacceptable overlooking of neighbouring gardens or windows. Side windows within 2m of a boundary are particularly sensitive.

Visual impact: A large extension that is oppressive or overbearing from a neighbour's point of view can be grounds for refusal.

To pre-empt neighbour objections:

• Show daylight analysis in your application drawings (45-degree diagrams)
• Specify obscure glazing for any windows likely to overlook neighbours
• Consider stepping back the extension at a sensitive boundary
• Talk to neighbours before submitting — a neighbourly conversation often prevents formal objections

A well-submitted application gives planners everything they need to assess the proposal efficiently.

Design and Access Statement: For most householder applications this is not required, but including a brief statement explaining the design rationale, local character analysis, and neighbour impact assessment is good practice. It demonstrates that the applicant has thought about planning policy.

Drawings: Submit drawings that clearly show:

• Existing and proposed floor plans at 1:50 or 1:100
• Existing and proposed elevations at 1:50 or 1:100
• Roof plans
• Site plan showing the property in context
• Sections where relevant

Poor quality drawings are a common reason for delays and requests for further information. Use a professional architectural draughtsperson.

Photographs: Include photographs of the property and its context. These help the case officer understand the site without visiting in person and are especially useful for complex sites or conservation areas.

Supporting statements: In conservation areas, a Heritage Impact Assessment (or similar) demonstrating that the proposal preserves or enhances the character of the area is valuable.

The materials you specify for your extension are scrutinised in planning applications. For London properties:

• Matching London stock brick is generally viewed very positively in conservation areas
• White render is common on late-Victorian and Edwardian houses and usually acceptable
• Zinc cladding for flat roofs and dormers is widely accepted in London as a contemporary but tasteful material
• Timber cladding can be acceptable if in keeping with local character but some boroughs discourage it on front elevations
• Dark powder-coated aluminium for windows and doors is broadly acceptable in contemporary extensions
• Very modern or industrial materials (exposed steel, Corten, black mesh) are harder to justify in residential conservation areas without a strong design justification

Overdevelopment: The extension is too large relative to the original house or the street. Reduce the depth or height.

Loss of amenity to neighbours: Extension causes unacceptable overlooking or daylight loss to neighbours. Step the extension away from boundaries, reduce height, or obscure-glaze sensitive windows.

Character of conservation area: Materials or form not in keeping with the conservation area. Use local materials guidance and seek officer input at pre-app.

Inadequate information: Application drawings are unclear or incomplete. Ensure all required drawings are submitted at correct scales with all required information.

Flat roof not in keeping: Some boroughs have policies against flat-roofed rear extensions in traditional terraced streets. Check local policy and consider a pitched roof if required.

If your application is refused:

1. Read the refusal reasons carefully — are they design-related or policy-related?
2. Consider whether a revised scheme addresses the concerns — minor amendments can often be resubmitted within a year without a new fee
3. Seek officer pre-application advice on a revised scheme
4. Consider an appeal — appeals succeed in approximately 30% of cases nationally, higher for householder applications

Most planning refusals that result from design issues are ultimately resolved by a revised application addressing the officer's specific concerns. Do not assume refusal means the project is impossible — it usually means a modified approach is needed.