How Much Can I Extend My House Without Planning Permission?

Want a bigger kitchen? Thinking of a loft conversion?

You might be asking yourself, ‘how much can I extend my house without planning permission?’

So, let’s clear this up once and for all.

Here’s a closer look at when you’ll need it, the reasons why and the exceptions to the rules.

When will you require planning permission?

If you make any major changes to your property, it’s likely you’ll need planning permission. This includes changing the use of your home (e.g. annex or shop), or building something new.

Doing the work without checking can result in you having to undo everything that’s been done. This also means you would lose all the money already spent, plus spending. Therefore, it’s essential you’re sure before proceeding.

Always apply for planning permission if you require it.

Even if you don’t need permission, restrictive covenants may prevent you from taking on any major building work, so it’s vital you check. 

Are there any exceptions?

There are many home improvements and renovations you can make without needing permission.

Even some ‘major’ building works do not require the hassle of the application process. However, it’s essential you know the rules.

Extension without planning permission

Extensions are considered a permitted development (meaning you won’t require permission) if they meet certain criteria.

These include:

• If it’s not higher than the highest part of the roof
• The materials are similar in appearance to the existing house
• It doesn’t include a veranda or balconies
• It’s no more than half the area of land
• Any upper-storey windows are obscure glazed

However, rules can differ based on the type of property, such as flats. There are also restrictions if you live in a conservation area, for listed buildings, or for areas of outstanding natural beauty.

If you’re unsure, it’s always best to check with your Local Planning Authority. Don’t simply assume – as the consequences can be huge!

Single-storey

Let’s delve a little deeper into some of the specific rules here.

You don’t need permission if your single-storey extension:

• Doesn’t extend beyond the rear wall of the original house by more than three metres (four if its a detached house)
• Doesn’t sit forward of the principal elevation

Side

What are the specific rules regarding side extensions that don’t need planning permission?

These include:

• If they are one-storey
• If they aren’t higher than four metres

Loft

To go ahead without planning consent, loft conversions cannot sit forward of the roof plane of the principal elevation.

Conservatories

Conservatories also fall under the same restrictions to one-storey extensions mentioned above.

Two-storey

What are the rules regarding two-storey extensions and planning permission?

You won’t need it if:

• It’s no closer than seven metres to the rear boundary
• It doesn’t exceed 3 metres in depth

Outbuildings and garden houses

Sheds and outbuildings usually don’t require planning permission, unless they exceed 50% of the land of the original house (curtilage). Also, you must ensure they’re only one-storey.

They also cannot be used for accommodation. However, you can use them to work from home.

Doors and windows

Usually, you can add or move doors and windows without needing approval. However, the rules differ if your property is listed.

For example, in some cases, bay windows count as an extension by some building regulations.

Garages and attached buildings

Unless your property is listed or in a conservation area, you can usually convert your garage into a living space without permission.

However, you need to make sure you’re not increasing the overall footprint of the building.

Differences apply if the garage is stand-alone.

Converting two homes

Dividing a single property into two will usually require an application.

However, in many cases, you can convert two into one without needing this.

Solar panels

Thinking of making your home more environmentally-friendly?

Attaching solar panels to the roof usually won’t require an application, unless your building is listed. Free-standing ones will have limits regarding size and proximity.

Minor roof or wall work

Improvements such as painting, adding a skylight or doing any minor maintenance work to the roof or walls usually won’t require permission.

Gates and fences

Permitted development allows you to add gates and fences that are under one metre next to a road. This isn’t the case if your property is listed, or if it forms a boundary with a building that’s listed.

You will need a planning application even if a fence isn’t next to a road if it’s over two metres high.

Creating new access

Whether you’ll need planning consent here or not all depends on the road you’re looking to create access from.

Unclassified roads usually don’t need permission, while classified roads do. There will also be restrictions on factors such as visibility.

Industrial/residential

Unless your property is listed, you should be able to convert an industrial or commercial building for residential use without consent.

Taking the next step

Carrying out any work on your home can be a daunting thought, however property refurbishment can add value. Therefore, when you come to selling it, you might find the asking price significantly increased.

Want to get a better idea of how much this will be? Use an extension value calculator before getting started.

This can give you an understanding of whether your planned improvements will add value – and how much. It can be tough knowing whether to extend or move, but many choose to add value to their property before finding another home.

Seek advice from the experts

When taking on any home renovation, it’s always a good idea to seek out expert advice. After all, the more you know, the more wisely you can spend your money. This could mean a greater return on investment.

This can give you peace of mind and point your project in the right direction.

Ready to get started?

Any building work is a large undertaking, therefore it’s important you know what you’re doing beforehand.

Find our advice on home renovation and maintenance here. From budgeting to planning, we’ve got you covered from start to finish.

Last Updated: January 10th, 2025