One of the most common questions that our clients ask is: how long does planning permission take? The short answer is that the statutory period for determining an application is 8 weeks for a household or minor application.

Larger or complex developments can, however, take up to 13 weeks. There are many factors which can affect the overall length of time from initial architect’s appointment to permission being received.

This article gives an insight into the length of the planning application process.

Architecture for London has achieved successful planning consents in the majority of London boroughs. View our portfolio of recent work, or contact us on 020 3637 4236 to discuss your project.


For a residential project, the time from an architect’s appointment to planning permission being received can take around 5 months including design time. For a larger project (e.g. developments of several homes), or if a pre-application is required, the amount of time can increase significantly.


What is required for planning permission?

Planning permission is required where any extensions and alterations to a property are not covered under permitted development. It is also required for a new build or replacement house, or a change of use of an existing property.

If planning application is not required, and the proposals fall under permitted development, it is recommended to apply for a certificate of lawful development.

planning permission design primrose hill

A 3D visual of a rooftop extension design submitted for planning by Architecture for London


A planning application is submitted via the online planning portal. From here it is sent to the relevant local authority. The application will require existing and proposed drawings, a site location and block plan, and often a design and access statement too. A form is filled out online, the documents are uploaded, a fee is paid, and the application is submitted.

Depending on the type of project and the local authority, additional information may be required.

This could include an arboricultural survey, other ecological surveys or a basement impact assessment.

How long is the design process?

After appointment, an architect will require a measured survey of the existing property. This can take around two or three weeks depending on a surveyor’s availability.

Once the survey is received, an architect will require time to discuss and draw up potential options with the client. This could take anywhere from one to three months depending on the size of the project.

The design process could include 3D modelling of the scheme to help explore and present design ideas. The outcome of this process will finalise the overall form and massing, internal layouts, window and door openings and the specification of external materials.


How long does planning permission take?

House extensions and alterations will require a householder planning application. A new or replacement house, increase in the number of units, change of use or larger development will require a full planning application. If your property is listed or in a conservation area, these will require additional consents.

Once the application is submitted, it is then assessed and validated. The application will be given a case number and allocated to a case officer. You will be notified in writing, and the application will be publicly available on the website of your local authority.

The decision date is 8 weeks from the date the application is validated. Some local authorities may backdate the decision to 8 weeks from the date of submission.

In our experience, while many authorities will return a decision within date, it isn’t uncommon for them to take longer.

Once your planning application is validated, the neighbouring properties will be notified, and they will be invited to submit their comments. They have 3 weeks in which to do this. Local neighbourhood groups, resident’s associations, amenity societies or conservation area committees may also be consulted.

The case officer will arrange a site visit to assess the existing site, take photographs and judge how the proposals relate to the context. If a large number of objections are received, the application can be decided by a planning committee.


Decision dates for planning permission

If an authority is not able to return a decision within 8 weeks, then it will require your consent in writing to extend the determination period. It is usually best to agree to their request.

If the application is taking a very long time to decide, then it is possible to appeal to the Secretary of State. This appeal is permitted on the grounds of ‘non-determination’.

Planning permission house extension

A 3D visual of a rooftop extension design submitted for planning by Architecture for London


If an extension to the determination period has not been agreed upon, there is a ‘planning guarantee’ from the Government. This commits the planning and appeal process to take no longer than a year. This should be 26 weeks for the application itself, and 26 weeks for any appeal to take place.

If the application has not been determined after 26 weeks, no extension has been agreed and the application has not appealed, the planning fee will be refunded.


Planning decision notices

At the end of the process, a letter will be received to formally notify you whether the application has been granted or refused. If the application is refused, reasons will be given.

The outcome of the application will be known towards the end of the 8 weeks. If an application is set to be refused the planning officer will offer the opportunity to withdraw it. This will need to be agreed upon in writing.

We don’t usually recommend withdrawing the application as then there is no opportunity to appeal the decision.

In our opinion, it is usually better to receive the refusal. If an application is refused or withdrawn, it is possible to reapply for no additional fee from the local authority.


Changes to an approved planning application

If changes are required to an approved application, it is possible to make changes in several ways. Minor changes are sometimes possible under either a ‘non-material amendment’ or a ‘minor material amendment’. Larger changes may also be possible under a variation of condition. Any other changes will likely require a further planning application.

Planning applications are valid for up to 3 years. If development has not been started by this date, the permission will expire. It will be necessary to renew the application if the development work is still to take place.

Sometimes conditions will be set as part of the planning approval. There be can pre-start conditions to the whole of the works, or conditions relating to a specific part such as roofing materials or brickwork. These will require an additional application to discharge them. Some conditions are for information only and will not require any further application.


How long does pre-application advice take?

In some instances, it is worthwhile to apply for pre-application advice. This precedes a planning application and the process will vary between local authorities. They will charge for this advice and are not required to return a decision within a specified time frame.

It may inform the design process to request pre-app advice for design options and assess the response. Some developments are of a complicated or uncertain nature.

Sometimes local authorities wish to be made aware of a more complex application before it is submitted.

The amount of information required for pre-application advice is similar to that required for a planning application. Pre-app advice charges will vary depending on the project, the local authority, and the type of advice required.

The response will be a written letter and can involve a meeting with a case officer. The pre-application and the advice received is private. Local authorities are not bound by the advice given, and it is not possible to appeal their advice.


View our portfolio of recent work, or contact us on 020 3637 4236 to discuss your project.


Summary FAQ

How long does planning permission take?

It takes 8 weeks from submission of an application to receive permission or a refusal notice. This is for a household or minor application.

How long is the design process?

This could take between one and three months depending on the size of the project.

What is required for planning permission?

The application will require existing and proposed drawings, a site location plan and often a design and access statement too.

How long does pre-application advice take?

There is no statutory time period for pre-app advice, but in our experience, the process can take around 8 weeks.