Working with experts, having a clear vision of how you intend to use your garden annexe and asking permission rather than forgiveness are three vital elements to making the most of your new outbuilding and adding the most value to your home.

In recent years, as families have remained close and multiple generations stay in the same home, so-called granny annexes have become increasingly popular self-contained living spaces.

Whether used to take care of elderly relatives, give teenagers and young adults a taste of independence or act as a place where guests can stay, a garden annexe can be vital when designed properly with the help of experts and dedicated tools.

However, the popularity of granny annexes has led to a few common errors that are often caused by rushing through the process and neglecting vital steps before paying the price later.

Here are the most common mistakes we see and how you can avoid them.

Why Do You Need To Work With Experts When Building A Garden Annexe?

A garden annexe is far more complex than a shed, log cabin or other basic outbuilding, acting almost like building a smaller house with its own security features and creature comforts.

Because of this, you cannot treat it like you would a garden shed; there are a lot of complexities such as insulation, connecting electricity, potentially connecting a gas line and a wealth of other factors needed to make a garden room safe and comfortable.

Whilst we offer a design tool so you can see the types of models available, it is essential to 

consult the experts before trying to build one to ensure it is done right.

Should You Seek Out Planning Permission Before Building A Garden Annexe?

One of the biggest reasons to consult an expert is that they can help you navigate the complexities of the planning system for garden buildings, as this is not a situation where you can seek forgiveness instead of permission.

Because of the size of garden annexes, they may not always be considered permitted development, particularly if they have multiple rooms or a second floor.

Because of this, it is always best to get in touch with your local planning authority with your intentions when it comes to a garden annexe. Asking now avoids the risk of fines or having to tear down a perfectly functional space later.

Minimising the amount of guesswork also helps reduce the stress of a construction project.

Is Your Garden Annexe Too Large?

Whilst it is important that your annexe is large enough for your extended family to comfortably live in, there are limits to how large it can be before it affects your chances of it being approved by your LPA.

The exact rules will vary by region, based on local needs and potential complications, but here are some of the general size rules you will need to follow:

  • The annexe cannot be larger than the main house.
  • The annexe should clearly appear to be an adjunct building
  • The larger the annexe, the more scrutiny it will receive from planners.
  • Overall, your extensions and outbuildings should not take up more than half of your garden area.

Any larger than this and your garden annexe may not be treated as a secondary outbuilding but as a separate house entirely, which could lead to all sorts of complex planning and legal entanglements.

Is Your Garden Annexe Actually A House?

The biggest advantage of a granny annexe is that it allows a degree of independent living, but whilst it is a self-contained space, it is not entirely independent from the main house, and that can affect its chances of getting planning permission.

This is why knowing exactly what you want to do with it matters a lot, as it will provide details that a planning council will infer from and ultimately shape their decision to grant permission or not.

In general, more than two bedrooms will arouse suspicion, as will an excess of extra rooms, a fully featured kitchen, multiple bathrooms and a range of extra rooms that could suggest it is meant to be used as a separate home.

This is important because separate dwellings require a different approach to planning approvals.

Does Your Garden Annexe Match Your Home?

Character matters, not just from the perspective of ensuring aesthetic cohesion but also from a practical planning standpoint.

If your planned garden annexe clashes with the existing body of your home, your design may be refused planning permission or cause objections from neighbours.