Guide to Planning Permission & Permitted Development Rights in London
Navigating London's planning system is complex. Between planning permission, permitted development rights, party wall agreements, building regulations, and borough-specific policies, there's a lot to digest before you can start building your extension or loft conversion.
This guide explains everything you need to know—with practical examples from Waltham Forest, Hackney, Brixton and Camden.
At Armstrong Campbell Architects, Leytonstone, we navigate these processes for clients across London. We are experienced in delivering planning applications and understanding what different local authorities require for approval. This guide is intended to share some of that knowledge to assist homeowners project planning.
Our overall strategy is always to be upfront, open and honest - we do not believe in playing games, or overly staged planning applications - these are clear to planning officers and only serve to increase time and cost, as well as unneccessarily congesting the planning system.
Journal post - Learn why working with an architect makes this process easier →
Planning Permission for London Extensions: The Complete Process
Planning permission is your local authority's means of controlling development. It ensures new buildings and extensions respect local character, protect neighbours' amenities and align with Local and National planning policies.
When You Need Planning Permission
You'll need planning permission if your proposed work:
- Exceeds permitted development limits (discussed more in this journal post)
- Affects a listed building
- Is in a conservation area (typically have greatly restricted permitted development)
- Involves significant changes to your home's appearance
- Could impact neighbours through loss of light, privacy, or outlook
- Is on a property with removed Permitted Development rights (Article 4 or planning condition typical on new estates)
Common London projects requiring planning permission:
- Two-storey rear extensions
- Large single-storey rear extensions
- Side extensions on corner plots or narrow sites
- Loft conversions with substantial dormers or roof alterations
- Front extensions or porches
- Basement conversions
The Planning Application Process: Step by Step
Step 1: Pre-Application Advice (Optional)
Before formally submitting, you can request pre-application advice from your local planning department. This typically costs £200-800 with a higher cost if a site visit is requested, the advice can also be given as a 'desktop study' approach. As an example, in Waltham Forest the homeowners advice costs £319 including VAT.
The process involves:
- Submitting outline plans and a brief description with existing photos
- Meeting with a planning officer (on site or virtual)
- Receiving written feedback on likely success and concerns
Is it worth it?
For straightforward planning applications then it is not usually worth the time or cost to pursue advice. In our experience, London councils have reasonably clear planning guidance and strongly rely on precedent projects. Therefore, we always begin our planning research with a Google Earth review and searching the councils recent planning applications for the postcode. Planning outcomes have detailed responses which will state why plans are either accepted or rejected.
For complex projects—conservation areas, contentious designs that go beyond the norm, extra-large extensions—then it would be worth considering pre-application advice. The benefit is to test the water at the same time as progressing the full application package.
Timeline for Pre-Application Advice
This varies between councils, but as an example, Islington commit to arranging visits within 20 days of receiving payment (homeowners will be contacted within 10 days to arrange a date). The visit will last around 30 mins and no definitive advice is given during the meeting. Islington Council commit to giving written advice within 30 working days (6 weeks) of the intial payment date. It is not a quick process and the cost is comparable to a planning application, which is why we only reccomend them if there are specific reasons on a potentially contentious site.
Alternative Pre-Application advice channels
If you would just like a quick call to discuss your project with an expert, Planning Portal now offer 30-minute calls with instant advice and feedback. These cost £72 for homeowners and can be booked online:
https://www.planningportal.co.uk/permission/planning-guidance-service
Step 2: Preparing Your Application
A complete planning application includes:
Drawings (typical scale):
- Location plan with site boundary in red (1:2500)
- Existing site plan showing boundaries and neighbouring buildings (1:500)
- Proposed site plan showing the extension (1:100)
- Existing and Proposed floor plans (1:100)
- Existing and Proposed elevations (1:100)
- Existing and Proposed sections (1:100)
Supporting Documents:
- Design and Access Statement (this is text and image based, explaining the proposal)
- Heritage Statement (if in conservation area or near listed building)
- Fire Risk Assessment's are increasingly more common following the Building Safety Act 2022 update post Grenfell Tower
- Other potential reports are Daylight Analysis, Tree Survey, Flood, Transport, Ecological - however these are on a case by case basis
Application fee: Varies by project type:
- Householder applications: £528 (as of 2025 the fee's were recently doubled to assist overwhelmed planning departments, although approval times remain at a minimum of 8 weeks)
- Prior approval (larger Permitted Development extensions): £240
- If your property is Listed, you will need to apply for Listed Building Consent, which is fee free from the council but may incur costs from your planning consultant (if Heritage Statement is required) or architect to prepare the additional documentation.
Step 3: Validation and Consultation
Once submitted, the planning department checks your application is complete (this is called a validation) and usually takes 1-5 working days to be validated. Typical reasons for not getting an application validated includes missing information such as CIL documents, admin errors such as incorrectly named drawings or an unpaid application fee. If the application is not validated, it is not a major issue, you can simply re-submit incorporating the comments, for no additional fee and it is fairly quick, although it pays to triple check the application prior to sending.
Then begins the 8-week consultation period (13 weeks for conservation areas as these are deemed "complex" projects)
- Neighbours are notified by letter
- A site notice is posted (for conservation areas)
- You can track objections and comments online
- Planning officer visits the site
- Internal consultees (conservation, trees, highways) review
Step 4: Planning Officer Assessment
The planning officer assesses your application against:
- National Planning Policy Framework
- https://assets.publishing.service.gov.uk/media/67aafe8f3b41f783cca46251/NPPF_December_2024.pdf
- London Plan
- Local Development Plan
- varies by local authority, available on each website
- Planning Application Documents listed above
- Previous decisions and local precedent
They'll consider:
- Design quality: Does it respect local character?
- Neighbour impact: Loss of light, privacy, outlook?
- Scale and bulk: Is it proportionate to the existing building?
- Heritage: Does it preserve or enhance conservation areas?
- Highways: Parking, access, traffic generation
- Trees: Impact on protected trees
Step 5: Decision
Planning officers can:
- Approve with or without conditions
- Refuse with reasons stated
- Request revisions informally where you withdraw and resubmit but this is becoming more unusual
Approval rate in London is around 80-85% for householder applications.
Conditions are common and are usually in place to ensure deveopments are safe, sustainable and fit the area.
Potential types of conditions include:
- Construction start date within three years
- Material clarifications and potential submital of physical samples
- Construction methodology including construction hours
- Environmental concerns in case of drainage, landscaping or wildlife
- Removal of permitted development rights to prevent future extensions
Key priorities for planning officers when reviewing applications
1. Respect for Local Character
Generic, catalogue designs often get refused in conservation areas. Officers want to see thoughtful responses to context—appropriate materials, roof pitches that match, window proportions that respect the streetscape.
2. No Significant Neighbour Impact
The 45-degree rule is a common test: if your extension projects beyond a 45-degree line drawn from the center of your neighbour's nearest habitable room window, it may cause unacceptable loss of light.
As well as this, extensions on houses with outriggers (the rear volume of house that is typical of London terraces and traditionally has lower ceilings with kitchen and rear bedroom) have restrictions on height of eaves to be no more than 2.5m. This does not include a parapet detail at the front elevation of the extension. This is to protect neighbours light and feeling of enclosure and is why so many London side return extensions have sloped soffits to one side, often with skylights.
3. High-Quality Design and Materials
London boroughs increasingly expect design quality, even for extensions.
- Proportionate windows and openings
- Appropriate materials
- Careful detailing
- Thoughtful landscaping and boundary treatments
4. Accurate, Professional Drawings
Professional CAD drawings with accurate dimensions, along with a completness of information within Design and Access Statements show care and confidence on applications. Critically, all information should support the application and all details or dimensions which are considered critical should be clearly annotated (eg 6m extension depths from rear facades as complying with permitted development rights) .
Dealing with Neighbour Objections
Neighbour objections do happen and don't necessarily mean a refusal as planning officers only consider material planning considerations - if a design is within planning policy then it will be approved, otherwise you would have grounds to appeal the decision.
Valid objections:
- Loss of light or outlook
- Overlooking and loss of privacy
- Overbearing scale or bulk
- Noise, traffic, or parking impact
- Design quality or character concerns
Invalid objections:
- Property value reduction
- Disputes over boundaries are a civil matter and typically dealt with via party wall agreements
- read our Party Wall Agreement journal post here
- Loss of view as this is not a protected right in the UK
- Construction disruption - contractors have regulations to work within such as working hours and noise.
How to manage objections:
- Engage with neighbours early, ideally before submission to dicuss your plans
- Adjust designs if there are legitimate areas of concern that can be accomodated
- Write clear Design & Access Statements
Everybody has a right to object on any planning application, the best process is always to keep open dialogue to prevent objections in the first place and avoiding the knowledge black hole and neighbours imagining worst-case scenarios. Fortunately in London, construction of extensions is so common, most neighbours just want to know things will be done well and professionally.
If Your Application is Refused
1. Review the Decision Notice: this will outline the grounds for rejection from the Local Planning Authority
2. Appeal: If you believe the refusal is unreasonable, appeal to the Planning Inspectorate. This takes 12 weeks for householder applications or 6 months for commercial projects. It costs nothing to submit but may incur professional costs. Success rate of appeals is around 30% for householder appeals. It is not a typically a route worth pursuing unless the design is unchangeable.
3. Redesign and resubmit: Usually, the Decision Notice provides clear reasons for rejection. If these can be rectified with an amended design, it is typically most efficient to make the design changes and resubmit a new application. The cost and timeline for the new application will match the original. If the Decision Notice is unclear, you can contact the Planning Officer to discuss their response in more detail.
Permitted Development Rights: Building Without Planning Permission
Permitted Development Rights allow certain home improvements without needing full planning permission. This saves the time waiting on planning applications and also cost less in fees—significant advantages.
What is Permitted Development?
Permitted Development Rights are a set of national rules defining what you can build without planning permission. They cover various home improvements including:
- Single-storey rear extensions
- Two-storey rear extensions
- Loft conversions
- Outbuildings
- Porches
- Solar panels
However, Permitted Development Rights come with strict limitations and important exclusions. It is important to fully understand these prior to starting a project as they cover a range of issues from volumetric, materiality and detailed setting out.
Single-Storey Rear Extensions
This is the most common use of Permitted Development Rights in London.
Standard Permitted Development limits:
- Terraced or semi-detached: Up to 3 meters from original rear wall
- Detached: Up to 4 meters from original rear wall
- Maximum height: 4 meters for pitched roof, 3 meters for any part within 2m of boundary
- Eaves height: Maximum 3 meters
- Cannot: Extend beyond side walls, use materials significantly different from existing, or take up more than 50% of garden
Larger Permitted Development extensions (with Prior Approval):
- Terraced or semi-detached: Up to 6 meters
- Detached: Up to 8 meters
For these larger extensions, you need Prior Approval (£240 fee and a 6-week process). Your neighbours can comment and if they object, the local authority will assess the impact on them. If approved or if there is no response after 6 weeks, you can proceed with the works. The recent increase in fee for Prior Approval means that it is sometimes beneficial to do a full planning application which will mean the works are assessed under less strict conditions, while taking only marginally longer to obtain.
Loft Conversions
Loft conversions often fall under Permitted Development Rights in London.
Allowed:
- Roof windows on any slope (flush with roof)
- Volume increase up to 40m³ (terraced) or 50m³ (detached/semi-detached)
- Maximum roof height same as existing
- Materials similar to existing
Not allowed:
- Dormer windows on front roof pitch (street facing)
- Balconies or raised platforms
- Increasing overall roof height
- Dormers that dominate the roof slope
- Dormers that are flush to the facade (300mm set back required)
Important Exclusions from Permitted Development Rights
Where PD does NOT apply:
- Flats and maisonettes usually have no rights
- Listed buildings will need Listed Building Consent
- Conservation areas have many permitted development rights removed
- Article 4 Directions is when local authority remove specific rights, usually associated with new housing developments
- Properties where rights were removed by previous planning condition
How to check: Contact your local planning department or check online planning constraints maps.
Lawful Development Certificate (LDC)
If you want absolute certainty that your project is permitted development you can apply for a Lawful Development Certificate (£150-400 fee). This provides legal documentation confirming your work doesn't need planning permission.
When to get an LDC:
If you are very close to Permitted Development limits it may be advisable to obtain a LDC. It should be received prior to starting work but can be requested by building control if they require proof works are within limits.
LDC applications take 8 weeks and do not involve neighbour consultation as they are checking against established rights to build.
Frequently Asked Questions
How long does planning permission take in London?
- Standard householder applications: 8 weeks.
- Conservation areas: 13 weeks.
- Prior approval (larger Permitted Development extensions): 6 weeks.
Can I start work while waiting for planning permission?
No - starting work before approval is illegal and can result in enforcement action requiring removal of work at your expense. Wait for the decision notice and ensure conditions are met before beginning any work requiring permission.
What happens if I build without Building Control approval?
It's illegal and creates serious problems:
- Local authority can serve enforcement notice requiring exposure of hidden work
- Regularisation (backdated approval) costs £1,500-3,000+ and may be refused if defects are found
- Lack of building control will create difficulty selling as this is always on solicitors queries, potentially reducing you rproperties ability to sell and subsequent value
- No peace of mind that works meet all structural and safety criteria - creating an unsafe environment.
Always obtain Building Control approval.
Do I need both planning permission and building regulations approval?
Often yes, but not always:
- Planning only: Some purely appearance changes (windows, doors, cladding)
- Building Regulations only: Work under Permitted Development still needs Building Control
- Both: Most extensions and loft conversions
- Neither: Very minor work (painting, decorating, like-for-like repairs)
Generally, if you're adding space or significantly altering structure, assume you need both.
How much do planning applications cost?
- Householder application: £528 (fees were increased in 2025)
- Prior Approval: £240
- Lawful Development Certificate: £264
- Pre-application advice: £200-800
Plus professional fees for drawings and statements.
Can my neighbours stop my extension?
No - they can object to your planning application but planning officers make decisions based on planning policy and not on neighbour preference. However, well-founded objections on valid planning grounds can influence decisions. Similarly, under the Party Wall Act, neighbours cannot veto any work but must allow works to proceed under correct process. Legislation is there to faciliate construction rather to stop it.
What if my extension fails Building Control inspection?
The inspector will note the failure and explain what's needed to pass. Your contractor can make corrections and then requests a re-inspection. Failures cause delays but are should be resolvable. This is why Building Control exists—catching problems before they're hidden or create long-term issues. Following good guidance with detailed submission packages and regular site visits, where the ongoing works are clearly displayed, should mitigate well against unforeseen rejection.
How long does Building Control approval take?
Full Plans approval takes 5-8 weeks typically. Once approved, inspections happen as the work progresses on site. This is usually within 1-2 days of a request to attend by the contractor. The Completion Certificate is issued 1-2 weeks after final inspection and signals Building Control is successfully obtained.
Contact us for Full Architecture Design Services, Planning Applications or to book a Home Design Consultation.
Read more of our journal guidance:
What to expect from working with an architect - Do I Need an Architect For A London Extension Or Loft Conversation? →
A detail dive into the design and construction process -
Guide To Building Control, Party Wall Agreements and Principle Designer Role. →
armstrong campbell architects
Based in Leytonstone, London
Residential and Hospitality Architects
House Extension | Loft Conversions | Renovations | New Builds
Last updated: December 2025
