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3 Tips For Granny Annexe Planning Success

As part of our turn-key granny annexe service, we offer advice, assistance and the latest approach to obtaining planning approval for your granny annexe.

The vast majority of granny annexes are built in back gardens and are typically for elderly relative care or downsizing in some way.

If you are thinking of building a granny annexe in the back garden, you will need planning permission and we’ve found some Local Planning Authorities have policies relating to granny annex building and some do not.

In all cases your Local Planning Authority will look at your planning application on it’s own merit and you will not find a consistent approach to the process throughout the country.

For that reason, we highly recommend that you take full advantage of our free on site consultation service to help you decide which is the best route for your particular annexe and your particular area.


Feature Article: 3 Tips For Granny Annexe Planning Success

Your dream granny annexe starts and finishes with successfully obtaining planning permission from your Local Planning Authority whether it is through the Householder Planning Application process or obtaining a Certificate of Lawfulness through what is referred to as “The Caravan Act.”

In 2016 we saw more applications being challenged by the Local Planning Authorities than ever before with regards specifically to the size of the annexe and whether in fact the annexe was for ancillary use.
Here are 3 tips for increasing granny annexe planning success.


1. Granny Annexes Rarely Come Under Permitted Development

Granny annexes are not considered a garden outbuilding, such as a home office or summer house, they are connected to mains sewerage, electric and water and are self-contained buildings built near the main house.
You will always need to apply for planning permission to build an annexe in the garden and this is usually best carried out by a professional company like ourselves rather than by an individual.


2. Every Local Planning Authority Will Deal With Your Enquiry Differently

Even though you would presume that planning policy is the same throughout the UK, your planning application will be dealt with on it’s own merit and will be open to the interpretation of the individual case office assigned to your planning application.

Most granny annexe planning applications are usually processed under a householder planning application (which are quite straight forward) however some Local Planning Authorities prefer the application submitted under a full planning application for which the fees are considerably higher.
We help you choose the best option for you on our free on site consultation service, sometimes choosing both to secure the best possible outcome for you.


3. Learning More About The Caravan Act

The main difference between the householder planning application and the Caravan Act is that the Caravan Act allows for a “structure” to be placed on site, providing it meets 3 specific tests and is defined in the Caravan Sites & Control of Development Act 1960 / Caravans Sites Act 1968.

The dimensions of your annexe are still very generous under the act:-

  • The maximum dimensions allowed under the act are:-
  • Depth – External 6.8metres (22 feet 3 3/4 inches)
  • Length – External 20 metres (65 feet 7 1/2 inches)
  • Ceiling Height – Internal 3.05 metres ( 10 feet 0 inches)

And the annexe must be built as a mobile home which is briefly classed as,

“Any structure designed or adapted for human habitation which is capable of being moved from one place to another (whether being towed, or by being transported on a motor vehicle or trailer.)

The process involved with obtaining planning permission is usually 8-10 weeks after your final design is decided. All Local Planning Authorities are extremely busy and dealing with all the new developments being built throughout the UK so professional preparation and submission is key.

The fee for preparing a Caravan Act Application and submitting it on your behalf to your LPA is currently £1,740.00 including VAT (terms and conditions apply).



  1. Granny annexes in back gardens will always require planning permission or a Certificate of Lawfulness from your Local Planning Authority.
  2. Granny Annexes can never be sold separately from the main house.
  3. Successfully obtaining planning permission on your behalf (although not guaranteed) is part of our turn-key granny annexe service.
  4. The planning application process typically takes 8-10 weeks once your drawings have been completed and your application submitted so you will need to plan ahead.

We look forward to receiving your thoughts and comments below or join in the conversation on our Facebook page!

Get in Touch

We’ve built over 150 garden annexes over the years, and have pictures of most completed projects. So, if you need further inspiration, and would like to view further portfolio images, please get in touch.

If you simply have a question for us, please submit your details, along with a quick message, and we’ll back to you ASAP. You can also reach us on 0808 1641111 or email us at enquiries@ihusprojects.com