How to Get Planning Permission for a Home Extension — A Step-by-Step Guide

The starting point is always Permitted Development (PD) rights. Under the General Permitted Development Order (GPDO), most homeowners in England have the right to carry out certain types of extension without applying for planning permission — provided the works meet specific conditions.

• **You DO need planning permission if**:
• •The extension is more than one storey (double-storey extensions always need permission)
• •A single-storey rear extension exceeds 4m depth (detached) or 3m depth (terraced/semi-detached) from the original rear wall — unless using the Prior Approval / Neighbour Consultation Scheme (which allows 6m/8m)
• •The extension exceeds 4m in height at the eaves for a single-storey extension
• •A side extension exceeds half the width of the original house
• •The property is in a Conservation Area and the Article 4 Direction removes PD rights
• •The property is listed — listed buildings almost always require Listed Building Consent (not a standard planning application)
• •The property is a flat (flats have no PD rights)

**The Neighbour Consultation Scheme (Prior Approval)**: for single-storey rear extensions between 4m and 8m depth (detached) or between 3m and 6m depth (terraced/semi-detached), the Prior Approval process is available. This is not a full planning application — it is a 42-day neighbour consultation process. If no objections are raised by affected neighbours, the extension can proceed.

**Always check Permitted Development first**: before assuming planning permission is required, check the PD conditions carefully — or ask a planning consultant or design-and-build contractor. Many homeowners apply for planning permission unnecessarily because they assume their project requires it.

A Householder Planning Application for a home extension typically requires:

• **Drawings**:
• •Location plan (Ordnance Survey based, scale 1:1250 or 1:2500, showing the site in context)
• •Site plan (scale 1:500, showing the site boundaries and layout)
• •Existing floor plans (scale 1:100 or 1:50, showing the current layout of the property)
• •Proposed floor plans (showing the new layout)
• •Existing elevations (drawings of all four sides of the house in its current form)
• •Proposed elevations (showing the new appearance after extension)
• •A section drawing (showing the cross-section through the extension)

**Application form**: completed Householder Application form (available via the Planning Portal or the local council's online system).

**Application fee**: £258 for a householder planning application in England (as of April 2024).

• **Supporting documents** (where required by the local authority):
• •Design and Access Statement (often required for Conservation Area applications)
• •Heritage Statement (for listed buildings or Conservation Area applications)
• •Flood Risk Assessment (for sites in flood zones)
• •Arboricultural survey (if trees are on or near the site)
• •Party Wall information (not part of the planning application, but sometimes referenced)

**Who prepares the drawings?** The drawings must be prepared by an architect or architectural designer. They are the primary professional cost associated with a planning application. Architectural design fees for a householder application are typically £2,000–£6,000 depending on complexity. In a design-and-build arrangement, the contractor's in-house designer or architect may prepare these as part of the pre-construction package.

Planning officers assess householder applications against the National Planning Policy Framework (NPPF) and the local authority's own Local Plan policies. The main factors assessed for a home extension application:

• **1. Impact on neighbouring amenity**:
• The primary assessment for most extension applications. Key questions:
• •Does the extension cause overshadowing or loss of light to neighbouring windows? (The 45° rule: a line drawn at 45° from the centre of the neighbouring window should not be broken by the extension)
• •Does the extension cause overlooking from new upper-floor windows into neighbouring gardens or habitable rooms?
• •Does the extension cause oppressive visual impact when seen from neighbouring properties?

• **2. Design and visual impact**:
• •Is the extension compatible with the design of the original house in terms of scale, massing, and materials?
• •Is it visible from the street (front extensions are the most sensitive; rear extensions less so)?
• •Does the roof form match or complement the original?
• •Is the window and door specification appropriate?

• **3. Conservation Area and heritage impact (where relevant)**:
• •In a Conservation Area, does the extension preserve or enhance the character of the area?
• •Does it affect the setting of a listed building nearby?

• **4. Highways and parking**:
• •Does the extension remove off-street parking in an area where parking is a concern?
• •Does the construction access plan include a Construction Management Plan?

• **5. Scale and mass**:
• •Is the extension proportionate to the original house?
• •Does it dominate the original house or neighbouring properties?

**Conditions**: approved planning applications often come with conditions — requirements that must be met before or during works. Common conditions include material specifications, hours of construction, drainage details, and landscaping requirements.

**Application fee (England)**: £258 for a Householder Application (as of April 2024)

**Validation**: the council validates your application (checks it is complete and the fee is paid). Validation typically takes 1–2 weeks.

• **Consultation period**: once validated, the council consults:
• •Adjoining neighbours (statutory letter notification)
• •Ward councillors
• •Specialist consultees (conservation officer, tree officer, highways, flood risk) where relevant
• The consultation period is typically 21 days from the date of notification.

**Statutory determination period**: 8 weeks for a standard householder application (from the date of validation, not the date of submission). This is a statutory target, but councils often exceed it — realistic timescales in London are 10–13 weeks in many boroughs. Conservation Area and listed building applications may take longer.

**Planning committee**: most householder applications are decided by a delegated planning officer decision. Applications are only referred to the Planning Committee if they are sensitive, attract significant objection, or involve a councillor's property. Committee meetings add time.

**Prior Approval (Neighbour Consultation Scheme)**: the 42-day clock starts from validation. Most Prior Approval applications are concluded in 42–56 days.

**Appeals**: if refused, you have 12 weeks to appeal to the Planning Inspectorate. Written representation appeals typically take 6–9 months. Hearings take longer.

A planning refusal is disappointing but not the end of the road. The options are:

**1. Redesign and resubmit** The refusal notice will contain reasons. Read them carefully with your architect or planning consultant. In many cases, the design can be modified to address the council's concerns — and a resubmission is free for the first resubmission if made within 12 months of the refusal.

**2. Appeal** If you believe the refusal was wrong, you can appeal to the Planning Inspectorate (independent of the local authority). The Planning Inspector reviews the application afresh. Around 35–40% of householder planning appeals succeed nationally. Appeals are free but take 6–12 months and require professional preparation.

**3. Pre-application discussion with the planning officer** Before resubmitting, request a pre-application meeting with the planning officer to understand exactly what would be acceptable. Most councils provide written pre-application advice (fees £50–£300 depending on the scope).

**4. Consider Permitted Development** If the refused proposal was only marginally over the PD thresholds, consider whether a revised design within PD limits would achieve a satisfactory result — no planning permission required.

**Prevention is better than cure**: the most effective way to avoid refusal is to have a pre-application discussion before submitting. A 30-minute conversation with a planning officer (or a written pre-application response) before spending £3,000–£6,000 on drawings often identifies the issues that would cause a refusal — and the design can be adjusted before submission.