Does your annexe or garden room need planning permission?

Q1. Will it include sleeping accommodation, a kitchen or bathroom?


Annexes are now a popular addition to many family homes to provide additional accommodation.

Mobile Home

NAPC provide a service to help you establish whether your mobile home meets the definition of a caravan and can apply for a Certificate of Lawfulness

Garden Room

Looking to install a garden room at your property? Unsure about planning permission or building regulations for garden rooms?

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Yes, planning permission may be required to site an annexe or garden room with these facilities.

However, depending on other factors you may be able to achieve this by gaining a certificate of lawfulness for the siting of a mobile home.


Planning permission may not be strictly required in these circumstances, as you can build a garden room under permitted development rights.

However, to ensure what you are doing is lawful, it is advised to obtain a certificate of lawfulness (COL), this invaluable if a neighbour complains or you sell your property.

Q1 Side Annexe

Q1. If your property is on designated land, do you intend siting your cabin to the side of the house?

What is designated land? Designated land includes National parks and the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites. On designated land outbuildings to the side of the house are not permitted development. We would advise you to consult your local planning department as there may be other restrictions.

Need Planning

You will need to apply for planning permission

Ok, so you are going to need to apply for planning permission. We suggest you talk to your local planning officer. The advantage of course, is that you can put in plans for your ideal log cabin without compromising on style or layout which you might have done trying to comply with permitted development rules. Gaining planning permission is a lot easier than people imagine and is granted in most cases. It costs around £150 and adds a few more weeks to the process but a ‘yes’ result will be well worth it.


Q2. If your property is in a national park or protected land, is your proposed cabin (and other outbuildings) more than 10 square metres if it is more than 20 metres from any wall of your house?

In national parks, the Broads, Areas of Outstanding Natural Beauty and World Heritage Sites the total area to be covered by any outbuildings more than 20 metres from ANY WALL of the house must not exceed 10 square metres to be permitted development.


Q3. Is your cabin to be sited within the boundary of a listed building?

Outbuildings are not permitted development within the grounds of a listed building.


Q4. Will your log cabin be forward of the principle elevation of your house?

Outbuildings are not permitted development forward of the principle elevation of the original house. The term original house means the house as it stood on July 1st 1948, if it was built before that date.


Q5. Is your cabin to be more than one storey high?

Outbuildings must be single storey to comply with permitted development rules.


Q6. Will your cabin exceed 2.5 meters high to the eaves?

The maximum eaves height of outbuildings should not exceed 2.5 metres.


Q7. Will your cabin have a dual pitched roof with an overall height of more than 4 metres – or be over 3 metres high with any other type of roof?

Outbuildings must have a maximum overall height of 4 metres with a dual pitched roof or 3 metres in any other case.


Q8. Will your cabin be over 2.5 metres high within 2 metres of a boundary?

If the outbuilding is within 2 metres of the property boundary the whole building should not exceed 2.5 metres in height.


Q9. Including your new cabin, will half the area of land around the “original house” be covered by additions or other buildings?

Outbuildings and other additions must not exceed 50% or half of the total area of land around the original house. Sheds and all other outbuildings and extensions must be included when calculating the 50% limit.


Q10. Will your cabin involve the construction of verandas or balconies?

Balconies and verandas are not permitted development.


Q11. Will your cabin involve the construction of raised platforms with a height greater than 300 millimetres?

Raised platforms such as decking are permitted development provided they are no higher than 300mm.


Q12. Do you intend your cabin to be separate, self contained, living accommodation or have a microwave antenna?

To be permitted development, any new building must not itself be separate, self-contained, living accommodation and must not have a microwave antenna.


No need to apply for planning permission

If you’ve answered all the questions correctly then you should be able to put your new log cabin in your garden under permitted development without applying for planning permission! However, if you have any doubts at all, we suggest you pop along and have a chat with your local planning officer.