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The difference between permitted development and planning permission in the UK is one of the first questions a homeowner or developer needs to understand before any building project begins, and it is one of the most commonly misunderstood.
Both sit within the same national planning system. Both govern what can be built and how. The distinction between them is not one of importance but of process: permitted development allows certain works to proceed automatically within defined national limits, while planning permission requires a formal application to the local planning authority and a considered decision against local and national policy.
Getting this distinction wrong at the outset of a project is one of the most common causes of avoidable delays, abortive costs and enforcement problems for residential homeowners and developers alike.
This guide explains both routes clearly, sets out the key differences between them and covers the circumstances in which each one is appropriate. It also explains when permitted development, despite being the faster and cheaper option on paper, is not necessarily the right choice for a specific project.
What Is Permitted Development?
Permitted development rights are a set of national planning rules, established under the Town and Country Planning (General Permitted Development) (England) Order 2015 and its subsequent amendments, that allow homeowners to carry out certain works without making a formal planning application. The principle behind permitted development is that some categories of work have a sufficiently limited impact on the surrounding environment that the full planning application process is disproportionate.
Permitted development is not a blanket permission. It is a set of precisely defined rules, each with specific criteria around size, height, materials, proximity to boundaries and the type of property involved. A project either meets all of the criteria and qualifies as permitted development, or it does not. There is no discretion and no assessment of design quality. If the criteria are met, the works can proceed. If any single criterion is not met, a planning application is required.
Common projects that frequently qualify as permitted development include:
Single-storey rear extensions within the depth limits (4 metres for detached houses, 3 metres for terraced and semi-detached houses), loft conversions within the permitted volume allowances (40 cubic metres for terraced houses, 50 cubic metres for detached and semi-detached), outbuildings within the permitted footprint and height limits, and installation of solar panels or air source heat pumps subject to specific conditions.
Common projects that do not qualify as permitted development include:
Extensions to flats or maisonettes, any works in a conservation area that alter the roofline or front elevation, basement conversions in most London boroughs, wraparound extensions and any works to a listed building.
What Is Planning Permission?
Planning permission is formal consent from the local planning authority to carry out development. It is required for any works that fall outside the scope of permitted development, and for any change of use of a building or piece of land. The application is assessed by planning officers against the local authority’s development plan, national planning policy and any site-specific designations or constraints that apply.
The planning application process involves submitting a package of drawings, forms and supporting documents, including a design and access statement where required. The local authority notifies neighbours and relevant consultees, publishes the application on its planning register and makes a decision within the statutory determination period. For householder applications, that period is eight weeks. For major applications, it is thirteen weeks.
Planning permission can be granted unconditionally, granted with conditions or refused. A refused application can be appealed to the Planning Inspectorate. Conditions attached to a permission must be discharged before certain stages of the works can commence, and compliance with those conditions is the responsibility of the applicant.
The planning application fee for a householder application in England is £528 as of April 2025. This is the fee paid directly to the local authority on submission and does not include professional fees for drawings and documents, which are charged separately. Our guide to architect costs covers the full picture of what a planning application involves in terms of professional time and cost.
Permitted Development vs Planning Permission: The Key Differences
The table below summarises the practical differences between the two routes across the factors that matter most to homeowners and developers.
| Permitted Development | Planning Permission | |
| Formal application required? | No | Yes |
| Decision maker | National rules (automatic if criteria met) | Local planning authority |
| Typical timeframe | No statutory period (LDC 8 weeks) | 8 weeks (householder); 13 weeks (major) |
| Design flexibility | Limited to set parameters | Greater flexibility possible |
| Applies to flats and maisonettes? | No | Yes |
| Applies in conservation areas? | Restricted or removed | Yes, subject to policy |
| Cost | No application fee (LDC: ~£234) | £528 householder application fee (2025) |
| Neighbour consultation | For larger extensions under prior approval only | Yes, standard part of process |
When Permitted Development Is the Right Route
Permitted development is the appropriate route when the proposed works clearly meet all of the qualifying criteria, the property is a house rather than a flat or maisonette, the site is not in a conservation area or other designated area that restricts permitted development rights and the design can be achieved within the permitted development parameters without compromising the brief.
In these circumstances, permitted development offers a straightforward path. There is no planning application fee, no eight-week determination period and no risk of refusal. The process is significantly faster and the outcome is certain provided the criteria are met. For a single-storey rear extension on a straightforward house in an unrestricted area, or a loft conversion that falls within the permitted volume, permitted development will often be the appropriate starting point. Our guides to rear extensions and loft conversions both cover how the permitted development rules apply to those specific project types in detail.
When Planning Permission Is the Better Choice
There are circumstances in which a planning application is not just required but is the better route even when permitted development might technically be available.
When more depth or scale is needed
Permitted development imposes strict limits on the size of extensions. If the brief requires more depth than the permitted development parameters allow, a planning application is the only route. A well-designed application can achieve considerably more than the permitted development limits, and in many cases the planning risk is lower than homeowners assume.
When the property is in a conservation area
Conservation areas restrict or remove many permitted development rights. Works that would be automatic elsewhere require a planning application, and the design quality of the proposal is assessed as part of the decision. In conservation area contexts, the planning application is not just a regulatory requirement but an opportunity to make a positive design case for the project.
When design quality matters to the outcome
Permitted development is a tick-box system. It has no design quality threshold: a proposal either meets the dimensional criteria or it does not. Planning permission, by contrast, is assessed partly on design quality. For projects where the design approach is a genuine differentiator, a well-presented planning application can unlock greater flexibility and achieve a better result than the constraints of permitted development would allow.
When the property has a complex planning history
Previous extensions count against the permitted development allowance. A property that has already been extended may have exhausted its permitted development rights entirely, regardless of the scale of the proposed new works. Checking the planning history before assuming permitted development applies is always the right first step.
For properties in particularly complex planning environments, our guide to conservation area planning in Richmond illustrates how the planning route decision works in one of the most demanding planning boroughs in the country.
The Lawful Development Certificate
For projects that do qualify as permitted development, obtaining a Lawful Development Certificate from the local planning authority is strongly recommended even though it is not a legal requirement.
The LDC is a formal document confirming that the proposed or completed works are lawful under the permitted development rules. It provides protection against future challenges to the permitted development status of the works, and it is the document that solicitors and buyers will expect to see when the property is sold.
Without an LDC, the lawfulness of the works rests on the homeowner’s own assessment that the criteria were met. That assessment may be correct, but it cannot be formally verified without the LDC, and an increasing number of buyers’ solicitors are declining to accept self-certification as sufficient. The cost of an LDC application is approximately £234 in England, making it one of the most cost-effective forms of protection available on a building project.
What the 2025 Planning Updates Mean
The government has made several updates to permitted development rights in recent years, with further reforms under active consideration as of 2025. The most significant change already in force is the relaxation of the rules for air source heat pump installations from May 2025, making it easier for homeowners to install low-carbon heating systems without a planning application.
Broader reforms to permitted development rights, including the proposed removal of the rule that restricts extensions to properties where more than 50% of the original garden has already been built over, were under consultation in 2024. No final decisions had been published as of early 2026, but the direction of travel in national planning policy is toward greater permitted development flexibility for residential homeowners. An architect with current knowledge of the policy landscape will be able to advise on what is available now and what may become available as reforms are enacted.
Understanding how these changes interact with the RIBA project stages, particularly the feasibility and planning stages, is part of how we advise clients on the best route for their specific project. Our guide to the RIBA stages covers how planning strategy fits into the wider project process.
Talk to Discover Architecture
At Discover Architecture, we advise clients on the right planning route for their project from the first conversation. Whether the works qualify as permitted development or require a full planning application, we manage the process with the same rigour and the same commitment to a successful outcome. Explore our services or get in touch to discuss your project.