Planning Permission And Granny Annexes Explained

"Granny Annexe Planning Permission"

The one thing that stands in between you and your dream annexe is planning permission to build it.

Whether it’s Planning Permission or a Certificate of Lawfulness, if you are planning to live in an annexe in your garden, it is seen by your Local Planning Authority as a dwelling (even though it isn’t) and therefore requires permission of some kind.

If you do not successfully obtain the relevant permission from your Local Planning Authority you may be forced to take your annexe down again via the Enforcement Office.

Obtaining granny annexe planning permission to build your new granny annexe will certainly put you through a whole range of emotions as you decide whether building an annexe in the back garden is the right thing for you and your family.

It’s a major decision that should not be taken lightly, but having spent many years working with people in the before and after stages of annexe building, it’s one of those decisions that usually has a very happy ending for all concerned.

A recent customer of ours decided to sell home & annexe number one to move and build home & annexe number two, they loved it so much.

We know that every situation is unique and we’ll endeavour to make the journey as smooth and stress free as possible.

And similarly when it comes to granny annexe planning permission, obtaining Planning Permission or a Certificate of Lawfulness, can either be straight forward and a breeze or in some cases a battle, either way it’s one that we have a 95% success rate with.

Let’s discuss what options you have and why you might consider them the right choice for you when it comes to granny annexe planning permission or obtaining a Certificate of Lawfulness (also known as the Caravan Act).

Working With Your Local Planning Authority

One thing that crops up very early in the decision making process is the daunting prospect of obtaining permission to build a granny annexe in your back garden from your Local Planning Authority (LPA).

Contrary to popular belief, a granny annexe with someone living in it on a day-to-day basis will always need either planning permission or a Certificate of Lawfulness from your LPA.

Ignore it at your own cost and always remember granny annexe planning permission will only ever be granted for a family member.

It’s a building that must be ancillary and subordinate to the main house.

Some temporary-style buildings such as leisure buildings (such a Garden Studios) that are not going to be lived in may not need planning permission. Annexes of the type and structure we build are what you would consider a “real annexe” and not some adapted log cabin or summer house masquerading as one.

Planning Permission or obtaining a Certificate of Lawfulness is definitely not something you should attempt yourself. It should be handled by professionals who specialize in obtaining residential planning permission in the UK.

With that in mind, and with a success rate of over 95%, it’s a service we offer to all our Contemporary Log Living customers because we want your application to be a successful one.

Your Local Planning Authority are going to be immensely busy and are far more likely to respond well to a company applying for permission on your behalf.

Granny Annexe Planning Permission And The Caravan Act

"bella vista mobile home annnexe"

You might have also heard a lot about the Caravan Act as being some kind of ‘silver bullet’ to getting an annexe built in your back garden and with good reason. In some circumstances we have recommended this route as the best option.

This will depend on each individual site, location and weighing up all the factors involved (including neighbouring properties and any past planning history).

We would also recommend the Caravan Act route where there are circumstances that would obviously create problems for Local Planning Authorities such as size.

Contrary to popular opinion Caravan Act applications can still be refused by your Local Planning Authority.

Most people are intrigued by the Caravan Act but misunderstand the type of building it refers to (which is similar in size and design of the annexe that would be built under the Residential Planning Permission route), but built to comply with the Caravan Act.

  • The Caravan Act is not just about caravans, it’s about the definition of a mobile home in general.
  • A mobile home is a structure that is designed for someone to live in that can be moved around the site if required. When you think in terms of a traditional building made of bricks and mortar this is of course a building fixed to it’s position and therefore not considered mobile. 
  • Mobile homes benefit from fairly relaxed Planning Permission restrictions as with the Caravan Act you are siting a temporary structure ( in this case your mobile granny annexe) within your garden and it is considered zero rated for VAT because it is classed as a mobile home.

The Definition Of A Mobile Home According To The Caravan Act

"Hampton residential mobile annexe"

In order to be defined as a mobile home under the Caravan Act, section 29 of the Caravan Act is very important to avoid problems further down the line.

The Caravan Sites Act 1968, as amended in England 2006 and Wales 2007 outlines the criteria for what constitutes a mobile home.

Size – wise to comply it must be:-

  • No more than 20 metres in length (that’s 65′ 6″ in old money as it were)
  • No more than 6.8 metres in width (that’s 22′ 3″)
  • No higher (internally, from the floor at it’s lowest point to the ceiling at it’s highest 3.05 metres (10 feet)

Some general guidelines with regards to the type of building it must be include:-

  • It must be a structure not a building ( ie. a mobile home / granny annexe)
  • Fit for human habitation
  • Capable of being moved from place to place including around the site once assembled. 

When you obtain planning permission to build an annexe in the back garden you are working with your Local Planning Authority to develop the land. They will have input on how it looks, what materials and finishes are being used on the outside, and which style and size they will accept.

With the Caravan Act you are applying to site a temporary building on the land not develop it. This side-steps a lot of the problems some people would have under the Residential Planning Application process but as we’ve said previously, it’s not a silver bullet.

All our granny annexes are classed as mobile homes which attract zero rated vat saving you thousands of pounds when compared to a home extension for example.

What Risks Are Involved With Granny Annexe Planning Permission?

Whether your best option for building a granny annexe in your garden is via the Caravan Act (where you will receive a Certificate of Lawfulness from your Local Planning Authority) or via the Residential Planning Application route (where you will receive permission to build an annexe in your garden with conditions specified by your Local Planning Authority) either application has the common denominator of getting permission to build of some kind from your Local Planning Authority.

When you are investing a significant amount of money in an annexe that is designed for someone you love to live in, quality of build matters.

You really want the water in the shower to be hot, the building to be well insulated and warm and the annexe to have all the comforts of a real little home at the bottom of the garden.

So why risk the future sale of your property by cutting corners or trying to do something and hope nobody will notice?

The most important piece of paper (whether it’s a Certificate of Lawfulness or Planning Permission) when you come to sell your property in the future will be your permission to build an annexe in your garden.

It’s also important to remember that if your best route is via the Caravan Act, then your annexe must comply to the Caravan Act and be built as a mobile home.

Buying a Granny Annexe should be a pleasant experience in our minds, and we will do everything we can to alleviate the stress involved when it comes to dealing with your Local Planning Authority (we use an annexe expert to advise and guide us.)

Granny Annexes And Planning Permission

This has been our preferred route for granny annexes and it’s the one most people consider “the proper route” or the one that is most familiar and the one they feel comfortable with.

Where we see Granny Annexes that we consider to be “straightforward” during our on site consultation (based on many years of building granny annexes of all types throughout the UK) we recommend the normal Householder’s Planning Application route which is the same type of planning permission you would apply for if you were building an extension or adding something to your garden such as a raised decked area.

In some circumstances a Full Application will be requested by some Local Planning Authorities that deem a Granny Annexe to be a new dwelling (this will require a further and significantly higher fee, it’s also going to be problematic as it’s an annexe, not a new dwelling (like self-building a new home for example) but it has to fit in somewhere.

There seems to be very little consistency with regards to this across Local Planning Authorities sometimes even within the same county.

Although the process is a well recognized one, Granny Annexes are not something that your Local Planning Officer may have dealt with before on a regular basis and they are likely to have concerns and questions that we would deal with on your behalf.

Your Local Planning Authority is likely to have concerns over things such as :-

  • The overall size of the Granny Annexe in relation to the main house and the size of your garden.
  • The specification of the living accommodation as it needs to be considered ancillary to the main house to be an annexe.
  • They will want to know the reasons why you want to build an annexe in the back garden, who will be living in it in the near future, and what long terms plans you have for it in the future.

Planning approval will only ever be granted when you fulfill all the requirements of your Local Planning Authority and in particular the concerns raised by the Local Planning Office who is in charge of your application.

The preparation of all the required drawings, application and design and access statements required will be carried out by our planning specialists or ourselves on your behalf.

All Local Planning Authorities abide by the same timescales when it comes to dealing with your planning application and will more often than not give a decision within the 8 weeks of them validating your submitted planning application.

Do you have any planning permission and granny annexe questions? Use our Facebook Page to let us know what you need help with!


  • All annexes require permission to be built in your back garden, we undertake this for you as part of our service.
  • The Caravan Act is a good route if you have previous issues or problems that would potentially be refused under the regular Planning Permission process, we’ll advise you on our free site consultations if there are any to be concerned about.
  • We have a success rate of over 95%  in obtaining planning permission via the Householder Planning Application process for annexes throughout the UK.

As always we look forward to your thoughts and comments below or join in the conversation on our Facebook Page !

Use The Contact Us Page To Email Us With Your Enquiry

Pete Cossie, Contemporary Log Living  

Sharing is caring!