You’ve finally made the decision to help an elderly family member by building them somewhere that enables them to still live independently, but with the reassurance that their family is nearby. So, do you need to apply for planning permission?

What permission do I need to build a granny annexe

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Read the rules

Recent changes in planning law means many people believe that a garden building falls under the permitted development rule, as long as it meets certain criteria. What some may not realise is this only applies if the new building is not going to be used for sleeping in.

According to the government’s Planning Portal, building regulations do not normally apply if the building is less than 15 square metres and contains no sleeping accommodation.

The government insists that a garden building does not need planning permission if it is going to be used for what it calls an ‘incidental’ purpose. However, an annexe which contains sleeping accommodation does not come under this definition, which applies only to garden sheds, storage buildings and other rooms used for a purpose that is incidental to the enjoyment of the main dwelling.

If a building is to be built for residential uses such as a separate self-contained unit that contains a bedroom, bathroom and kitchen, it will require planning permission. and this can lead to confusion for homeowners. This rule is explained in the government’s technical guidance document for England and Wales, but is not always made clear on the internet. This is why, if you are considering erecting an outdoor building for use as a granny annexe, you should consult an expert for advice. You might want to consider a company such as which has experience of planning law and building regulations and can guide you through it, saving you time and hassle.

Practical solution

Despite the complex rules, building a separate accommodation unit for an elderly relative can be a good way of caring for them in a practical way, which allows all family members to retain some independence. You don’t need a lot of space to build an annexe and using the right design company will mean you get exactly what you need, with a made to order building that is high quality and provides everything your family member needs to live comfortably.