Building regulations and planning permission

When it comes to extending and renovating your home, planning permission, building regulations and party wall agreements can be a real headache. 

Then there's permitted development rights, which allow homeowners to undertake smaller-scale projects without submitting a planning application.

To understand what each of these terms mean and whether they apply to your renovation, read our simple guide.

Find out more about extension planning and extension costs on our dedicated pages.

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Building regulations

Any renovation project must comply with building regulations, regardless of planning permission. Building regulations are the minimum standard for design, construction and alterations to every building. 

You can apply to any local building control department or approved inspector for building regulations approval.

Anything that falls under building work needs to be covered by building regulations, including:

• The erection or extension of a building
• An alteration project
• The insertion of insulation into a cavity wall
• The underpinning of the foundations of a building
• Work affecting thermal elements, energy status or energy performance of a building. 

Ensure whoever carries out the work can either self-certify the work they do (for example, FENSA accredited window fitters, Gas Saferegistered gas engineers and NICEIC registered electricians) or liaise with the local Building Control Officers at your local council to have their work certified. 

The responsibility is usually down to the builder, but always confirm this at the very beginning. Bear in mind that, if you're the owner of the building, you'll be the one served with an enforcement notice if the work doesn't comply.

If the requirements aren’t met, you could be ordered to take the extension down or you may have trouble selling your home in future without the relevant building regulations certificates.

Permitted development rights 

Permitted development rights are a more relaxed version of planning permission. It's not granted by the local authority, but by Parliament. 

Permitted development allows homeowners to make alterations to their properties quickly without having to go through planning, if the impact on neighbours or the surrounding environment is likely to be small. This can include extensions, loft conversions, roof lights, solar panels and windows. 

As of May 2019, a rear wall of a detached home can be extended by 8 metres to the rear if it’s a single story property, 3 metres if it’s double storey and 6 metres in a semi or terraced house, without the need for planning permission. These rules were put into place temporarily five years ago, but have now been made permanent.

There are also height restrictions – a single story extension should not be higher than 4 metres in height to the ridge and the eaves, and ridge heights of any extension should not be higher than the existing property. If the extension is more than half the area of land around the original house, you'll need planning permission.  

If you go for building regulations approval, it's advised that you notify your local authority and apply for a Lawful Development Certificate to ensure you have the proof that development fell within these rights. These applications tend to take about 10 weeks for a decision. 

Permitted development rights are different for buildings such as flats, maisonettes and commercial property, so check the rules for the type of property you own. Also find out whether the building is in an area where rights are more restricted and different rules apply, such as a conservation area or national park. Plus, any renovations to a listed property will need listed building consent.

It's worth noting that the government ran a consultation on increasing the scale of renovations that can skip planning in early 2024. The objective was to 'seek views on changes to several existing permitted development rights that allow for householder development, building upwards to create new homes, the demolition of certain buildings and rebuild as homes, electric vehicle charge points and air source heat pumps'. The feedback is currently being analysed.

Discover 6 home renovations that don’t need planning permission

Do I need planning permission for an extension?

Planning permission is required in the UK to build something new on land, make an alteration to a property or to change the use of a property. 

The local planning authority decides whether a development should go ahead. This ensures people don't just build structures wherever they want or use land in any way they want. 

Navigating planning permission can be confusing. Most new buildings and major alterations to existing buildings need permission, although as mentioned above, some minor building works which fall under permitted development, don't need planning permission. 

We asked homeowners about the planning permission problems they've experienced and how to avoid them

How long does UK planning permission take? 

UK planning authorities have statutory time limits to deal with planning applications, which vary depending on where you live. 

You'll be required to submit an application, which takes a maximum of 10 weeks to be decided, including a two-week validation period and an eight-week decision period.

Allow plenty of time for planning permission approval. The more complex your plans, the more likely it is that the deadline will be extended or missed, so try and get your application right before submitting.

Make sure you’re prepared for delays and have a plan for what to do if you can’t start work as scheduled. If a delay leads to you losing the contractors you’d hired, you can use Which? Trusted Traders to search for builders in your area to help you get your project back on track. All endorsed traders have been through our rigorous assessment process and have signed up to the Which? Code of Conduct.

How to apply for planning permission

Homeowners in England can apply online to every local authority in the country via the Planning Portal.

Most local authorities will also accept a planning application by email or post.

Those in Wales can apply via Planning Applications Wales. If you live in Scotland, visit eDevelopment.scot, or visit the NIdirect if you live in Northern Ireland.

You can consult your local planning department for help. Basic advice is usually free or you can get more formal ‘pre-application advice’ for a fee. Architects can also help with this phase of the process.

Note that in most cases there will be a planning application fee. The cost of planning permission varies depending on the scale of your project. Calculate a figure for a worst-case scenario, including possible extras such as bat surveys, and allow some contingency in your budget. 

Get help working out the fee from online tools such as the Planning Portal's online fee calculator or from your local authority.

Finally, monitor the progress of your application so that you don’t miss any actions you need to take and respond quickly to any requests from the planning authority. 

Wondering where to start with a home extension? Read our advice from a builder and an architect

Party wall agreements

A party wall is a shared wall, usually between a terrace or semi-detached house, and divides the homes of two separate owners. Party wall agreements are something you need to know about it you’re planning an extension or renovation next to an adjoining property in England or Wales. 

The Party Wall Act 1996 is designed to help you undertake work, while protecting the interests of your neighbours.

Party wall agreements are most commonly needed for loft conversions and extensions which require the insertion of steel supports, a damp proof course or new foundations.

If building work affects a party structure, you must serve notice at least two months before work begins. In the case of excavations, you must give at least one month’s notice. Work can begin once an agreement has been entered into.

Before serving notice, chat to your neighbours informally about your plans and make sure they understand what you're planning to do. To serve notice, you need to write to all adjoining homeowners, stating your name and address, a full description of the work, access requirements and the start date. 

Provide your neighbour with details of the Party Wall Act so they know what they're agreeing to – you can download the Planning Portal's explanation of this.

Your neighbour has 14 days to respond and give their consent or request a party wall settlement. If they agree to the works in writing, you won't require a party wall agreement and this can save on the fees.

If a property is leasehold, you'll need to serve notice on both the tenant and the building’s owner.

Find a party wall surveyor at the Royal Institution of Chartered Surveyors (RICS). 

Read our guide to extensions costs to discover the average cost for a single and double-storey extension, calculated using RICS data