Can I Build A Granny Annexe In My Garden?

If you are considering turning part of your outdoor garden into a granny annexe for an elderly relative or loved one, you’re probably wondering where to start.

The good news is that, in most cases, you will be able to build a granny annexe in your garden, as long as the space is suitable and you secure the right permissions. Most UK gardens have enough room for a self-contained granny annexe, and planning departments are very familiar with this type of build, especially when it’s intended for a family member.

To make an annexe possible, you’ll typically need:

• A suitable plot within the boundary of your property (the “residential curtilage”)
• Enough space for the annexe footprint and safe access
• Planning permission or a Certificate of Lawfulness
• A design that meets local planning guidelines
• Access to utilities, such as water, electricity and drainage

If your garden meets these basic requirements, there’s a very strong chance you’ll be able to build an annexe and our annexe specialists can help you understand exactly what’s achievable on your plot.

Will I need planning permission for a garden granny annexe?

The simple answer is yes.

The mixed messages you might hear usually come from the fact that different types of garden buildings fall under different rules. While structures like log cabins, summerhouses, and garden offices can often be built without planning permission, a granny annexe is treated differently if it is intended to be lived in.

For an annexe, you’ll typically need to apply for planning permission or a Certificate of Lawfulness from your Local Planning Authority (LPA).

Our preferred route is a Householder Application, but we also submit the same plans under the Caravan Act as a back‑up. This dual approach gives you an additional layer of protection should any objections arise and helps keep the planning process as efficient as possible, so building work can begin promptly once approval is granted.

So that begs the question: Do I need planning permission to build a garden annexe?

What are the advantages of working with a granny annexe specialist?

The government’s online guide to planning permission is where most self-builders head first when starting a project of this size and scale. But the closer you look at the ‘ins’ and ‘outs’ of garden annexe planning permission, the more confusing it can become. That’s why many homeowners, and first-time annexe builders, prefer to talk to an expert.

Our simple four-step process means you get expert help and advice every step of the way. And that includes looking after and applying for planning permission on your behalf – so you don’t have to worry or stress about it. With a 94% success rate, we’re confident we can help get your garden annexe off to the perfect start.

“We could not have wished for a better company to build our annexe! Every single employee at iHus that we have had any interaction with has been so friendly, professional, & co-operative from the very first phone call of enquiry through the entire sales, planning, build and handover. Even today, 4 years later, iHus have an after-sales care team that is second to none.”   

Kate Cama.

The best way to get the ball rolling is to book a free virtual consultation and have a chat with one of our experts. They will be able to talk you through the whole process and in the long run, save you time, stress, and money.

Does the Caravan Act mean I don’t need permission to build a granny annexe?

Some companies claim you can avoid the planning process altogether by building your annexe under the Caravan Act. This route can apply in certain situations, which is why it’s often promoted as a planning‑free option. However, it’s important to understand that the Caravan Act only covers structures that meet specific criteria, and not every proposed granny annexe will qualify.

In most cases, a garden annexe will still be treated as a permanent residential structure by the LPA, which means full planning permission is required. As part of the application, planning officials will look at questions such as:

• How the annexe sits within your plot?
• Is the annexe is in keeping with the character of the local area?
• Will the structure affect or impact your neighbours?
• How will the build affect nearby buildings or land?

LPAs are very familiar with annexes, and applications are assessed on clear planning principles. Even if your initial idea needs adjusting, for example, to better suit the available space you have, that doesn’t mean your annexe dream isn’t achievable.

Speak to one of our annexe specialists at the start of the process and learn about the best route to a successful build for you and your family.

Four steps to a successful granny annexe build

While applying for planning permission can seem daunting, there are a few simple steps you can take to give yourself the best possible chance of success for your granny annexe:

• Get in touch and book a free virtual consultation. It won’t cost you a penny and you’ll get all the answers you need from our annexe experts.
• Let us do the legwork when it comes to applying for and securing planning permission.
• Take what your friends and colleagues tell you about planning permission with a pinch of salt (however knowledgeable they may seem). For the facts, talk to us, check out our FAQs, or meet the people who have already been through this process.
• While no application can ever be guaranteed, our experience, 94% success rate and no-win, no-fee guarantee, will give you the best possible chance of approval without risk.

Ready to speak with us?

If you have any further questions, no matter how specific, please get in touch with one of our experts. We’re here to help and we’ll be happy to talk you through the different granny annexe options, and how to make the most of your outdoor space.

To help you continue your annexe journey, here are some related guides to explore.