Planning permission: a beginner's guide

Need to know about planning permission? Chartered surveyor Peter Richards explains how the planning process works – read on if you’re considering extending or converting your home and may need to apply

Planning permission guide: shows an extended house with mountains in the background
Mulroy Architects
(Image credit: Joakim Boren (Mulroy Architects))

Planning permission, also known as planning consent, is the formal permission from a local authority for the erection or alteration of a building. Planning permission is something you'll almost certainly need if you're considering a major project – and may need if you're planning an extension or dramatic house renovation. It is also required for a change of use of buildings or land. Here, we take you through the essentials of planning permission. 

So, if you're extending a house or approaching a house renovation find out everything you need to know about planning permission.

Do I need planning permission?

It is always worth checking with your local council to find out whether you need planning permission for your project, and what is likely to be accepted. You can also double check the government's planning portal to see restrictions. 

Currently, if you are planning and designing single storey extension, you can add an 8m extension to a detached house or a 6m extension to a semi-detached property without planning permission. 

If you're planning and designing a double storey extension, you may also be able to extend without planning permission. This applies if, for example, your extension is no taller than the highest part of your existing roof; if it does not extend beyond the rear wall by more than 3m; if it is at least seven metres away from the boundary; and if it is built in materials to match the original structure.

But, again, it's essential to check first with your local council first. 

Most houses have permitted development rights (PD), which generally cover minor extensions, demolition and certain changes of use, such as: 

However, flats and maisonettes do not fall under PD, so planning permission is required. Planning permission is also more likely to be required in conservation areas, National Parks and Areas of Outstanding Natural Beauty, but not in the Green Belt.

Planning permission infographic

How much does planning permission cost?

Planning permission application fees vary depending on the nature of the application – you can use the government's planning portal to calculate costs. Welsh authorities have a different fee schedule, and applications for listed buildings or those in conservation areas don’t incur a fee.

How to apply for planning permission

You’ll need planning permission for significant extension and remodelling projects, and you can apply either through your local authority or online through the planning portal. Follow our step by step guide to applying for planning permission to find out more.

planning permission flowchart

How long does it take to get planning permission?

Local authorities will usually advise of a target determination date when validating your application. For small-scale projects, they normally aim for eight weeks from validation to decision.

Planning permission guide: a terraced house with large side extension and box dormer

(Image credit: Alison Hammond)

How long does planning permission last?

As a general rule, and unless stated otherwise in the letter notifying you of the decision, three years. This means that you should start work within that three-year window, or you will need to re-apply. 

Take note of planning conditions

If you’re lucky to receive an approval for your planning application, be 
sure to make note of the conditions attached, as they are just as important. Most approved applications come 
with notes, such as requiring the local authority to approve the exterior materials before commencement of work, or perhaps having sign off on 
a landscaping scheme.

You’ll need 
to formally apply to discharge these conditions and receive a letter to confirm so, as failure to do this will invalidate your approval. 

Planning permission for extensions: making changes to your design

You may need to tweak your design after gaining approval, for which you have two options: either use the minor amendments route, which is designed for issues like new window positions, 
or submit a new planning application. Avoid this by studying your plans in detail and have a physical or digital model created to help with visualisation.

If the changes are very slight, it is possible to apply for a 'non-material amendment', but significant changes, such as the extension's overall height or the position of upstairs windows, for example, would be judged as 'material', meaning planners would have to advertise your plans again, in which case you may need to submit a new application.

The minor amendment route costs £28 and takes 28 days to decide, while another full planning application would take eight weeks but is free if applied for within a year of the original.

What if the planning application is turned down?

‘First, it’s important to try to understand exactly why the planning application was rejected,’ says architect Hugo Tugman. ‘The proposals may be largely acceptable, but simply contain a detail that the local authority can’t approve, in which case resubmitting a new application that has been amended accordingly should be enough to get the permission that you require.

‘It may, however, be that what you are proposing is fundamentally outside the planning policy or guidance the planners are working with. If that is the case, you really need to understand what these policies are and redesign so that your scheme falls within these parameters.

‘The third possibility is that you feel your scheme was within the policy guidance, but the planning department has made an unreasonable interpretation of the rules and refused it. In this final case it may well be worth going to an appeal, where an inspector (not local authority) makes an independent assessment of whether policy has been applied correctly and reasonably.’

What are Section 106 agreements?

These are legal agreements that run alongside some planning applications. They allow local authorities to secure monetary contributions to offset the impact of the proposal or control restrictions on the planning consent being sought. Normally, Section 106 agreements are reserved for larger applications, however, some local authorities are now using them to secure affordable housing contributions for developments of single plots, so it’s worth checking the local policy.

Will a tree preservation order be a problem?

It would be advisable to contact the council to ascertain whether the tree has a preservation order on it. If you are in a conservation area, you will also need to get special consent.

5 more planning permission tips and tricks

  • Most planning decisions should take no longer than eight weeks from the point of application.
  • The objections of neighbours and local people may well not have any impact on the final decision.
  • If you think you are going to get a refusal, you can withdraw your application at any time up to the day itself, and resubmit free of charge.
  • You can submit an infinite number of planning applications on any one site — and choose which to use, as long as it is current.
  • You can make an application on any piece of land in the country, without having to own it.

Planning permission not needed? Apply for a Lawful Development Certificate

If you are certain that your project does not need planning permission, but want to be able to prove it is lawful in future – perhaps when you're moving house – it is worth applying to your local authority for a certificate of lawful development. 

An application needs to be submitted to your local authority. The forms are typically the same across all local authorities and can be accessed, completed and uploaded via

You will need to submit scaled plans of your proposal and a location plan based on an up-to-date ordnance survey map. 

Don't forget the other paperwork: building regulations and insurances

Remember that getting planning approval is not the only legislation you need to adhere to. Proposed works will also need to conform to building regulations if they include structural alterations. So repair work won't need to, but new building work – including extensions – will need to be checked.

You also need to remember that if you are extending your home, it will not be covered by standard buildings insurance. Extensions and extensive renovations are often excluded from buildings insurance if you are altering the structure of your home. You will need specialist site insurance to cover the existing insurance and the new works being carried out until completion.

More about extending: 

Lucy Searle
Lucy Searle

Lucy is Editor-in-Chief of, having worked on numerous interiors and property titles. She was founding Editor of Channel 4’s 4Homes magazine, was Associate Editor at Ideal Home. She has also written for Huffington Post, AOL, UKTV, MSN, House Beautiful, Good Homes, and many women’s titles. Find her writing about everything from buying and selling property, self build, DIY, design and consumer issues to gardening.