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Can I Build A Granny Annexe In My Garden?

Can I Build A Granny Annexe In My Garden?

BeforeBricks Marketing Team
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October 14, 2021

According to the valuation office agency there are 39,000 granny flats in England. Granny flats, also known as granny annexes, are becoming a better solution for the aging population of the UK as the idea of being in a care home and away from your family seems daunting.

They are just not for the aging population but young people trying to get on the property ladder.

Due to the price increase in good care homes for older relatives, you’re probably considering if you can put a granny annexe in your garden.

The answer is yes, lets dive into this topic in more detail and explain how it works.

What is a granny annexe?

Granny flats falls under the category of a tiny house, granny flats are self-contained one or two bedroom homes that are usually detached from the main house as an extension for a member of the family.

This self-contained living space will contain all the commodities of a house such as a kitchen, bathroom, bedroom, and living room.

Do you need planning permission for a granny flat?

Planning permission for outbuildings such as granny flats will be determined by the purpose of the building. If the granny flat is being used for just recreational purposes, then it will not need planning permission. This type of building falls under your permitted development right, also popularly known as ‘incidental outbuilding’.

Permitted development right is a scheme introduced by the government to enable homeowners to expand their property if it follows the right rules and regulations. Permitted development right can get tricky which is why is it advised to hire an architect to discuss your options with you.

On the other hand, if the granny flat is being used as a living space for another family member, then planning permission will be needed.

Why you need Planning permission for granny flat Granny flats are extensions that are away from the main home, but if they are simply extensions of the main home that are attached and meet all building regulation rights then planning permission is not required.

There are a few considerations that you can make before submitting planning application to your local authority to ensure that you are granted planning permission.

Firstly, consider the size of your new granny flat, it should clearly just be large enough to house one or two people and should be a lot smaller than the main home in size.

Consider your neighbours and ensure that the granny flat does not affect their dwelling in any way. It should not cast a shadow on your neighbour’s property or enable viewing into their property.

The granny flat should generally have more than one access due to emergencies and to meet building regulations.

The final decision will depend on your local council and different councils vary so try to carry out some preliminary research into what your local council requires. Having informal conversations with them about the granny flat before you begin planning permission application will help to gauge their opinion on your design and if it will be approved.

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What are the planning regulations specific to granny flats?

A few of the planning permission laws to keep in mind when building a granny flat are:

• It must not be more than half the available area of land to be built on

• Materials used to build the granny flat must be like those used for the original house

• When within two metres of any boundary the eaves cannot be higher than three metres

• The granny flat must not exceed more than four metres of a detached property if attached to the

original house

What type of planning application do I need to submit to the council to gain approval for a granny annexe?

There are four main types of planning application in the UK, they are:

  1. Full application
  2. Householder application,
  3. Outline application
  4. Reserved matters application

A full planning application is the most common type in England, UK.

It involves the submission of the complete details of the development being proposed, and the detailed drawings that show the site being developed on. Householder application is for homeowners that want to carry out developments in their homes or in their gardens, all the details of the development will be submitted in one application.

Outline application is done as a preliminary check to see if the development will be approved before a fully detailed planning permission proposal is submitted. This is usually done for larger schemes such as new housing developments.

Reserved matters application is submitted once outline planning permission has been approved of.

Reserved matter application must be submitted to the council before construction starts.

This usually will include all the information about the development such as floor plan layout, size, access points, façade details, etc.

However, for a granny flat the planning permission application required is House holder application in most cases as they classify as outbuildings for dwelling.

There are certain cases that planning permission is not needed but this will have to fall under the category known as permitted development.

Planning Permission for granny flat in conservation area/listed building.

If a granny flat is being built in the backdrop of a listed building or it is in a conservation area the council will require further details to consider the planning application permission.

In these cases, application should be for full planning permission and usually condition is attached to this if approved.

Any work that affects the character of a listed building will require listed building consent from your local council.

Most common reason planning permission is rejected

In certain situations, granny houses planning permission is denied which is why it is advised to hire a professional when designing one as they are trained professionals.

They will be able to guide you and provide the relevant drawings needed to apply for planning permission.

The most common reason why planning permission is denied is usually the size of the granny flat.

Usually, the granny flat is seen as too big in relation to the size of the area available to be built on, or too big when compared to the main home.

To increase your chances of obtaining planning permission try to follow these simple rules:

• Carry out a site survey on the land being built on and this should be done by a professional architecture firm

• It is better to leave the plans and drawings that will be submitted to your local council in the hands of a professional and don’t try to do it by yourself as refusal is a long process to appeal.

• Get advice from professionals and book consultations with architects that can give you the right advice

By following this advice, you can make the planning permission application process easier for your granny flat.

Permission planning applications usually depends on the planning officer’s opinion on whether the building should be allowed to commence.

The planning laws in the UK are open to personal interpretation and so many variables. If planning application is denied, appealing the decision could take another 6 months.

Alternatives to building a granny flat

There are ways to get around not applying for full planning permission, another popular route is the Caravan Sites Act.

A typical granny flat would require a foundation and would be a fixed fixture ideally in the garden.

Granny flats that can move and are not fixed to the ground fall under the Caravan Sites Act.

Is planning permission required for a granny flat?

The cost to build these is usually less and the planning application process is not as complicated. It can easily be sold to another family and can be transported to another home if the family decides to move in the future.

Whether you decide to build a movable granny flat or a fixed one it is still recommended to obtain a Lawful Development Certificate to avoid any issues in the future with your new investment.

Things to consider

Once you have decided that a granny flat is the right type of extension for you there are certain points to consider as you commence on this project.

Although not seen as the most ambitious construction that could occur in your back garden it can become a stressful process if not considered properly.

The list of advice given below if followed will ensure that you have a new granny flat to enjoy within a few months:

• Hire an architecture profressional or consultant, although you can carry out the drawings yourself, your chances of getting planning permission will greatly increase.

• An on-site consultation is advised as this will enable the architect to give you the right advice of what your options are.

• Existing building drawings can be drawn up by the architect which you can use to inform your design idea.

• Planning drawings should be drawn by an architect with your needs being the inspiration behind


• While you wait for a decision from your local council you can begin to consider hiring a builder.

If approved be prepared for inspection checks to ensure that the new granny flat meets building regulations.


With the rise of granny flats in the UK and the benefits they have it is not surprising that they are becoming a suitable solution to many problems that modern day families face.

They do require planning permission since they are a dwelling space that is typically built away from the main home.

But if they meet building regulations and they are approved by the local council they are a tremendous project to begin.

House holder planning applications ensure that the granny flat is approved by the local council and a Lawful Development Certificate will enable the project to carry on without any interruptions from the council.

Although planning permission application can be denied if the size of the granny flat is not considerate to the surrounding environment, if simple rules are followed this can be avoided and alternatives such as caravans can be used to ensure that you still get your ideal granny flat.

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