Thinking of extending your home – what are the planning rules?

publication date: Jul 16, 2015
author/source: Kate Faulkner, Property Expert and Author of Which? Property Books

Thinking of extending your home - what are the planning rules?


I often wonder how on earth home owners and investors manage to keep up to date with all the rules and regulations. They can change so quickly in the property world, and are often media headlines one day and then nothing is said the next.

What makes things more difficult to understand when it comes to extending your home, is it’s not just what you read in the newspapers or hits the media about the planning laws that applies.

What factors affect extensions to your home? 
There are five key factors which determine whether you need planning:-

  1. National rules and regulations which apply to property extensions
  2. Whether your property has been extended before
  3. How big your garden area is
  4. Whether your property is Listed
  5. If your property is in a Conservation Area

National planning rules

Well, prior to 2013, this was fairly simple! However, since 30th May 2013 and until 30th May 2016 the rules have changed. The rationale behind the rule changes is to help encourage homeowners to spend more money on tradesmen and materials to help boost economic growth.

Be aware though, this rule change applies to England only. In the UK, housing laws are different for Wales, Scotland and Northern Ireland, sometimes they take on the schemes – such as Help to Buy, other times they don’t.

What is the rule change in England? 
Prior to May 30th 2013, the rules to extend your home were:-

  • Semi-detached and terrace properties, you could extend up to three metres
  • Detached homes, you could extend up to four metres

Now, in some cases, you can extend your property by:-

  • Up to six metres for a semi-detached and terrace property
  • Up to eight metres for a detached home

And you may be able to do this without having to go to the expense and time of securing planning permission. But the local authority will still have to secure permission via a ‘neighbourhood consultation scheme’.

Remember though, if you don’t need planning permission, even works as small as fitting a door with glazing, changing the electrics or drainage, may need sign off by the building regulations officer.

Check with the Planning portal to find out more about national planning rules and regulations in England.

How can you tell if your property has been extended before? 
The reason you have to do this is because every home comes with something called ‘permitted development’ ie an amount the property can be extended by. Once this is eaten up by previous owners or yourself, you have to apply for planning if you want to make the home any bigger.

To check if a property has been extended is pretty simple. Most property types have a ‘similar’ footprint. For example, an old 200 year old farmhouse is typically a long rectangular shape with three rooms downstairs and three upstairs – here’s a picture of mine.

Kate's period farmhouse

Now you can see that there is a long bit on the end. This was the old barn which was converted and attached to the house, so mine has already been extended. You can also see there is a conservatory (of sorts!) which has been added on. So my house has already been altered.

A 1930s or 1950s property look pretty similar too. One or two rooms deep, three or four beds and a garage which hasn’t been built over yet.

Sometimes you can tell a property has been extended as the brickwork is plainly different or it has a flat roof rather than a pitched one.

If you really aren’t sure, then you can check with your local planning office and they will go through their files or even pop out to see you to clarify if your permitted development rights have been used.

How big your garden is
You might wonder why on earth the size of your garden is important. But it is. The reason being, whatever else the rules say, you can only extend your property to 50% of the size of the garden – typically the original size.

This isn’t always an easy one to measure, so to make sure you don’t have any nasty surprises, check with your local authority if you are getting anywhere near extending into your garden.

Is your property Listed?
Whether you are buying or own a Listed property already, the rules are very different to any other type of property, in any area.

The key rule to know and understand for Listed properties is talk to your planners before you do anything at all. Different local authorities have different views on changing properties, and some are more strict than others, so you can only do what they allow you to.

If you are thinking of starting a renovation project read our Quick Guide first.

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All our information is brought to you by Kate Faulkner, author of Which? Property books and one of the UK's top property experts.
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