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Home & garden.

Updated: 12 Jul 2021

Do you need planning permission for a garden room?

What you need to know about planning rules and whether you need permission for your dream garden room, office or log cabin.
Sarah Ingrams
People planning a structure.

You’ve found the garden room you want, worked out where to put it and are already looking forward to spending time in it. But before you buy, it’s vital to check whether you need to get planning permission.

The size of your room, where you plan to put it, for what you plan to use it, and where you live all impact whether or not you will need planning permission. 

Some firms will apply for planning permission for you, if needed. This is more likely if you’re buying a substantial structure and the company will be installing it in your garden too.

Garden room planning permission 

Most garden rooms don't require planning permission. They are classed as outbuildings, so you're allowed to build one as long as you comply with certain rules. 

That’s as long as you have permitted development rights at your home or the area you live in.

You might not have permitted development rights if:

  • your home is a listed building
  • your home is in a designated area (eg a National Park, area of outstanding natural beauty (AONB), conservation area or World Heritage Site)

Check with your local planning office if you’re not sure. Flats and maisonettes don’t have permitted development rights.

The rules are the same whether you live in England, Northern Ireland, Scotland or Wales.

Find out more about loft conversion planning permission and planning rules for extensions. Use Which? Trusted Traders to find a reputable firm near you.

Woman sitting in garden office surrounded by craft materials

Garden room planning rules 

If you want to construct your garden room under permitted development, you’ll need to make sure it meets the following rules, wherever you live in the UK:

  1. Your garden room or log cabin isn't in front of your home. If you have extended it then the front refers to how it stood on 1 July 1948.
  2. The total area of all extensions, sheds and outbuildings - including your proposed garden room -  must not cover more than 50% of the total area of land around your house. Again this is the area as it was on 1 July 1948. 
  3. It is single storey and less than 3 metres high (4 metres with a dual-pitched roof). If it’s within 2 metres of your boundary, the maximum height is 2.5 metres.
  4. The eaves are no more than 2.5 metres above ground level.
  5. It doesn't have a balcony, veranda or raised platform.
  6. It isn’t self-contained living accommodation.

If you live in a National Park, the Broads, a World Heritage Site or an AONB, the maximum area of outbuildings that are more than 20 metres from your house is 10sq m. 

In National Parks, the Broads, World Heritage Sites, AONBs and conservation areas you’ll need to get planning permission if any part of your garden room would sit between the side of your house and the boundary of your property. 

If you live in a listed building, you’ll need to get planning permission for any outbuilding.

Man sitting in a circular tiled garden office next to a field

Planning permission for garden offices

Permitted development rules cover outbuildings, including garden rooms, which are ‘incidental’ to the main dwelling. Essentially this means that their use is a minor accompaniment to the main house.

Working on your own on your computer in your garden office is more likely to be an ‘incidental’ use than using it as a base for clients to come for meetings or appointments on a regular basis. This would have an effect on the neighbourhood.

In the latter case, your council could ask you to apply for planning permission retrospectively. If it isn’t granted, you’ll have to take down the building.

Check with your local planning office if you’re not sure whether how you plan to use your garden office is ‘incidental’.

Garden rooms and Building Regulations 

Building Regulations are about how a structure is designed, built and insulated. Having the right certificates is important, as they’ll be needed if you sell your house.

However Building Regulations don’t usually apply to outbuildings, as long as:

  • it’s not attached to your main home
  • the floor area is less than 15 sq m 
  • it doesn’t include sleeping accommodation. 

If the floor area is between 15sq m and 30sq m, you still don’t usually have to apply for Building Regulations approval, as long as there's no sleeping accommodation and it’s more than 1 metre from your boundary and is made of non-combustible materials. 

It will need to comply with Building Regulations if you ever plan to sleep in it or use it as a guest bedroom.

Electrics in your garden room will need to comply with part P of the Building Regulations. For example, if you have a separate consumer unit in your garden room you’ll need to get a qualified electrician to connect it to your mains supply. They will test that the system is safe and issue a certificate showing that it meets the relevant Building Regulations. 

Read more about adding utilities in your garden room or summer house. Find reliable electricians near you with Which? Trusted Traders.

Garden room with bathroom 

You may need planning permission for your proposed garden room if you intend to use it for activities that you would usually do in your main home, such as showering or cooking. 

To have a cold water supply to your garden room you’ll need new plumbing installed. This involves two sets of pipes – one to bring fresh water and one to remove waste water.

For fresh water will need a connection to your mains water in your house. Your waste water pipe may be able to connect to an existing drain. If this isn’t possible, you might need a pump to move the waste water to an outside drain.

If you’re hoping to have hot water, small hot-water heaters are an option. They can be installed under a sink and provide about 7-10 litres of hot water. 

Fitting a toilet will probably require a macerator to reduce waste to a pulp. It will also need to be connected it to a soil pipe to take waste to the main sewer. 

Read more about adding plumbing in your garden room or garage.