Whilst there are some garden annexes small enough to classify under permitted development, many extensions and outbuildings require planning permission, and it is always best to ask your local planning authority first before making a costly mistake.

Because of the often-ambitious design of granny annexes in particular, which are often designed to be relatively independent dwellings compared to the main building, they often push against the limits of what is allowed in your home.

This is why you need to work with experts in extensions in order to make sure that you not only have the right design to meet your needs but that your construction and design team work with you in order to get the legal and regulatory permissions you need.

With that in mind, here are some of the most frequently asked questions we get regarding planning permission for garden annexes.

Are Garden Annexes Considered Permitted Developments?

There are certain general rules when it comes to planning permission for outbuildings, which are directly applicable to garden annexes, where you may not need to apply for planning permission.

The general rules are that a garden annexe may be considered permitted development as long as it fulfils the following conditions:

  • It is not at the front of the house, defined as the wall which forms the main elevation of the house.
  • It is single-story with a maximum eaves height of 2.5 metres and a maximum overall height of three metres for most types of roof (except for dual-pitched roofs which get an extra metre of allowed height).
  • It does not have a balcony, veranda or raised platform of any kind over 0.3 metres.
  • It does not, alongside other extensions, cover more than half of the land surrounding the “original house”.
  • It is not constructed on “designated land”, which includes national parks, areas of outstanding national beauty, World Heritage Sites and conservation areas.
  • It is not being built in a listed building area.
  • It is not subject to an article 4 direction.

Garden annexes, particularly those that are designed to be lived in relatively independently, can be somewhat complex cases, and you should let your local planning authority know of your intentions before you commit to construction to ensure that it is okay to build.

Can You Get Planning Permission Retroactively?

You should never rely on retroactive permission, and there are many cases where a garden annexe is built, or construction starts before planning permission is rejected.

A particularly noteworthy example was reported in The Mirror newspaper, where the director of a civil engineering company in Worcester constructed an L-shaped annexe without requesting planning permission first.

The local planning authority in this case, Worcester City Council, argued that it was a self-contained residential accommodation, which can be much harder to get planning permission for.

In this case, the retroactive permission was rejected on grounds of overdevelopment; several appeals were also rejected, and the director in question was later given just six months to demolish the “summer house”.

What Are The Consequences If You Do Not Get Planning Permission For Your Garden Annexe?

In most cases, including the Worcester director who built an illegal garden annexe, the main enforcement action for what the law defines as a breach of planning control is to issue an enforcement notice to define the scale of a breach of planning permission and state what needs to be done to fix it.

Exactly what this enforcement can entail will vary depending on the offence in question; it usually requires the homeowner in breach of planning regulations to take down the offending building at their expense, but it can sometimes involve unlimited fines and further penalties.

The latter is usually reserved for violations of listed building consent, in situations where an outbuilding is added to land considered to be part of a listed building without acquiring both planning permission and consent from the relevant heritage authorities.

There is often a statute of limitations on enforcement notices and planning violations, often known as the ten-year rule, which means if an outbuilding exists for ten years without deliberate attempts to hide it, it may be given planning permission even if it would not have qualified.

Is It A Criminal Offence To Build A Garden Building Without Planning Permission?

In many cases, not getting permission is not by itself a criminal offence, although if the courts have gotten involved and an enforcement notice has been ignored, that enters the realm of criminal liability.

As well as this, there are some special cases where a garden building is illegal immediately without other crimes such as contempt of court being involved:

  • Building a garden annexe in a listed building without permission is technically a violation of listed building consent and is a criminal offence the second that unauthorised work begins.
  • Any work that damages a protected tree is illegal.
  • If a garden building has an advertisement fitted to it without advertising consent, it could be illegal, and even legal signs can be forced to discontinue.
  • If the garden building’s construction requires the removal of a protected hedgerow, it could be a crime under the Hedgerows Regulations 1997.