We’re getting more and more enquiries about building annexes.

When we hear the term “annexe”, the immediate association is usually a granny annexe. And whilst many of our enquiries are about space for an elderly relative, an annexe is no longer the preserve of grandparents. It can be a great option for independently-minded teens, or young adults who can’t afford to step onto the property ladder. Or even as a space for the live-in nanny or au pair. The mix of independence and proximity can be the ideal solution in a growing number of cases.

By definition, an annexe must be associated with the main home in some way, but it does not have to be attached. It is generally a self-contained bedroom, living space, bathroom and kitchen. Although the size and complexity will, in part, be dictated by the available space.

The social benefits of building an annexe

Living as a multi-generational family can be fantastic for all involved. Elderly relatives have company close at hand. If they’re still fit and able, they can also be a handy source of childcare! The reported health benefits of older people living with family can make them less reliant on the state for care.

But the extra bit of independence that an annexe affords (as opposed to living within the family home) can help keep relationships strong. Family members can keep out of each other’s hair when they need to! With a lack of suitable first-time homes on the market, this can be particularly useful for young people who want more independence but simply can’t afford to move out.

The financial benefits of building an annexe

Rising house prices, and the lack of properties on the market, are forcing families to become more inventive. Opting for an annexe can make financial sense for all involved. Household bills can be split, childcare costs could be reduced. It could also be much more cost-effective for elderly relatives than paying for care in their own home, or the cost of residential care.

Do you need planning permission for an annexe?

The short answer is yes. In the majority of cases, the fact that someone will be sleeping in the annexe means you will need to apply for planning permission. Development will not usually be granted under permitted development.

It’s important to be realistic. You’re not likely to get permission for a full-sized bungalow with multiple bedrooms in your garden by passing it off as an annexe! The proposed building needs to be appropriate for your house, garden and surroundings.

The only exception may be if you’re converting an existing outbuilding, such as a garage. But rules will still apply, so you will need to investigate planning fully before carrying out any work.

As with all building work, if you’re in a conservation area, getting permission is likely to be more complicated with more rules needing to be adhered to.

It’s really important to get things right at the planning stage so your annexe is not treated as a separate property (which can have implications for things like council tax). It’s important to bear in mind that the permission you’re granted may prevent the separate sale of this part of the house.

And don’t forget building regulations. Your annexe will need to be fully compliant, including considerations for fire safety routes and sound proofing.

Things to think about when planning your annexe

  • An annexe is not a cheap or quick fix solution. It’s not to be undertaken lightly. But will create a beautiful home.
  • The amenities you can fit in your annexe obviously depends on the space you have. A full kitchen may not fit. Discuss these details with your intended occupant at planning stages to make sure everyone’s happy with the result.
  • Agree some ‘rules’ before you get started. Talk about the degree of privacy each party expects. Who will do the chores? What behaviour is acceptable? Who will be responsible (financially and otherwise) for repairs and upkeep?
  • If your annexe has a separate front door, it may be subject to additional council tax. There are exceptions (relatives, dependents, over 65s), but make sure you’re clear on this before you start.
  • Be clear on any additional stamp duty implications (a tax regime change in 2016 saw some families with annexes hit by bills as they were reclassified as “second properties”). Again, certain conditions apply but it pays to check this out before you embark.
  • Think about ownership of the property in a financial, and legal, sense. Will it be owned as “joint tenancy” or “tenants in common”? What’s best might depend on how much each party has invested. It’s important to understand the implications as this could directly affect your living arrangements now, and in the future. This may also be significant should a mortgage be needed to cover the cost of building.
  • Think about other financial implications including whether the annexe will count as an asset should the inhabitant need to move to care, or for inheritance tax purposes. It makes sense to get some advice from an independent financial adviser at the same time as planning your annexe.