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Building a Home Annexe

By: Lucy Debenham BA (hons) - Updated: 29 Jan 2017 | comments*Discuss
 
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Building a home annexe is one way to create more space within the boundaries of your property. It’s also a great way to maintain a degree of separation or privacy for the annexe building’s occupants, whilst retaining a strong link to the main heart of the family home.

For this reason a home annexe is also commonly referred to as a ‘granny annexe’, as they are an excellent way for an elderly relative to life in a self-contained annexe but hold on to more than a modicum of independence.

Whether you are planning on building a home annexe for this reason or not, there are several considerations you’ll have to make before you even begin to lay the first brick. This article looks at the basic fundamental planning permissions and regulations relating to the building of a home annexe.

Planning Permission & Buildings Regulations

When thinking of building a home or granny annexe, one of the first questions people often ask is whether they will need planning permission. It is nigh on impossible to answer this definitively, as each case is individual and can be subject to local planning by laws or restrictions placed on the house.

It also depends whether the annexe is classed as an extension (attached to the house and accessible from the interior, or not more than 5 metres from the house), or is going to be a detached self-contained building. If treated as an extension, you would most likely need to obtain planning permission.

If accessible from the interior of the house via an internal interconnecting, it will usually be treated as part of the main dwelling. So effectively the annexe would again be treated as an extension. If the annexe is a separate dwelling within the boundaries of the house and it’s land, then certain other buildings regulations will apply, such as fire safety routes and sound proofing.

You should note that anyone that intends to reside in the separate dwelling with a separate door for access would most likely have to pay additional council tax. The exceptions are usually relatives, dependents (including those that are mentally or physically impaired) and persons over the age of 65. In these cases you will need to complete a special annexe exemption form.

Use of Your Home Annexe

The classification of the new annexe will also depend on your intended use for it – it could be classed as a separate dwelling if self-contained and occupied by someone that doesn’t otherwise live in the house. If it’s intended for business use, it will definitely need an application. However, if the use of building is classified as ‘ancillary’, i.e. it may not need an application if it also applies to any of the following:

  • Under 10 cubic metres in volume
  • Not intended for business use, e.g. office from which a business is run, parking or storage related to the business
  • Under 3 metres tall with a flat roof or 4 metres high with a pitched roof
  • Not closer to any other highway (e.g. bridleway, road, footpath) than the main house
  • Not going to take up more than half of the area of the land around the original house
  • Not in an Area of Outstanding Natural Beauty, a National Park, a Conservation Area or The Broads
  • Not on the site of a house that is a listed building

This can vary between local planning authorities and the only way to be sure is to call your local planning officer for more information. Therefore the information submitted in this article relating to planning permission applications and buildings control approval is intended as a basic guideline only.

Converting an Existing Building to an Annexe

Many people may choose to convert an existing garage or outbuilding to create a home or granny annexe. This can require the material change of a building. You will have to meet and obtain building control approval, as many garages do not have adequate heating, insulation or fire safety routes. Installing or replacing a garage door with windows may also require building control approval.

You should consider that some houses with self-contained annexes would appeal to a smaller house buying demographic, therefore although the value of your house might increase, you will effectively be selling to a smaller market.

Alternative Annexe Buildings

Therefore a popular home annexe solution is to erect a log cabin in the garden. Log cabins are fantastically adaptable spaces, and many will not require planning permission (see above) if classed as an ancillary building.

If intended as a separate dwelling, they can be easily insulated and soundproofed, and fire safety routes and other buildings regulations are simple to comply with. Therefore, as long as your garden is big enough usually planning permission is easy to obtain. And the bonus is that a log cabin can be easy on the eye and form an integral part of your garden landscaping or garden design!

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Share Your Story, Join the Discussion or Seek Advice..
[Add a Comment]
We have been renovating our house for last 7 years turning the 80's nightmare to a nice modern space. We've got bored and now want to sell to start a self build project. we finished the main house leaving the annex downstairs. We are wondering whether to leave as is and let the new owners decide what to do - bring in to rest of house or renovate annex etc. We initially planned a master bedroom, ensuite and snug. Do we leave as is or throw some money at it? It really is in need of some tlc.
Trine - 29-Jan-17 @ 3:53 PM
Ernie - Your Question:
I have a four bed house but all rooms are extremely small. The house was built as part of an estate in the 1980s. The rooms are so small that there is no room for wardrobes and chests of drawers. I bought the house for the huge garden and pond which is on a separate title deed. All owners before me have sold and moved on due to the work needed to maintain the pond and land and due to them growing old and weak. I am 72 and I want to stay in my house until I die. To do this I need to share my house and land with my daughter and her family and by doing so they will help with maintaining the large pond and land and trees and shrubs. In this way we could all enjoy the land and pond. But--the house is too small and I can't extend because of main sewers on either side. The only way for me to stay here until I did is to build on the land and use it like an annex suitable for me and my wife to live in whilst my daughter and her family live in the main house. Then, we can all live happily and have enough hands available to maintain the wonderful pond and land and keep it wonderful for the wildlife which uses it. Owls, herons, ducks, badgers, squirrels, snakes and all kinds of wildlife. If I can't get permission I may as well sell and move yet again and try and forget the wonderful pond and garden. What are the chances of getting planning permission to build on the land for an annex?

Our Response:
We really can't tell you that as we don't know anything about where you live etc. Your local council's planning officer will be able to give you an idea of your chances of building an annex.
AGardenBuilding - 17-Nov-16 @ 2:27 PM
I have a four bed house but all rooms are extremely small. The house was built as part of an estate in the 1980s. The rooms are so small that there is no room for wardrobes and chests of drawers. I bought the house for the huge garden and pond which is on a separate title deed. All owners before me have sold and moved on due to the work needed to maintain the pond and land and due to them growing old and weak. I am 72 and I want to stay in my house until I die. To do this I need to share my house and land with my daughter and her family and by doing so they will help with maintaining the large pond and land and trees and shrubs. In this way we could all enjoy the land and pond. But--the house is too small and I can't extend because of main sewers on either side. The only way for me to stay here until I did is to build on the land and use it like an annex suitable for me and my wife to live in whilst my daughter and her family live in the main house. Then, we can all live happily and have enough hands available to maintain the wonderful pond and land and keep it wonderful for the wildlife which uses it. Owls, herons, ducks, badgers, squirrels, snakes and all kinds of wildlife.If I can't get permission I may as well sell and move yet again and try and forget the wonderful pond and garden. What are the chances of getting planning permission to build on the land for an annex?
Ernie - 16-Nov-16 @ 9:58 PM
My fiancé and I viewed a property and really wanted to purchase it. Fortunately prior to involving Solicitors etc. it came to light that it had an outstanding planning permission/Certificate of Lawful for existing use/development case on it regarding change of an outbuilding to an independent one bed dwelling to allow the Vendor to sell the main house and continue to live in the outbuilding which is a like one bed bungalow with all amenities (bathroom/kitchen/bedroom) and it is situated in the back of the garden to the main house, separated by a fence.The Vendors have been living in the bungalow for around 8 years whilst their Son resides in the main house with his family following a financial change in his circumstances. Unfortunately the Council have now refused the use of the outbuilding as an independent one bed dwelling ontwo occasions now with the reason that 'it has not been demonstrated, on the balance of probability, that the outbuilding has been used as an independent dwelling for four years or more'.This is despite their application submitted with up to 20 independent confirmations and some sworn declarations.It would seem to be a little personal with the Council and the Parish Council.I have a copy of the recommendation report should this help and a further detail as to why the Council may have refused is because the Vendor didn't formally separate any of the utility bills etc./change of address as his Son is in the main house and there was no need to formalise it all up until now when he wants to sell the house. The Council do not appear to be taking that aspect in to account. Following a conversation with the Vendor yesterday, who is desperate to still sell the main house and remain in the outbuilding/bungalow, he is going to submit an appeal.Do you think that they would win the appeal?How long do appeals usually take? If they never get the certificate for change of use/independent dwelling, could we still buy the main house (which they are willing to sell) and draw up a very fixed legal agreement allowing the Vendors to live in the outbuilding/bungalow until their demise but we would own it as it's not a separate entity to the main house?Is this illegal for allowing someone to stay in the outbuilding? Could the Council make them take out the kitchen/bathroom etc? Another option If the appeal got refused is should they change the use from outbuilding to Annexe and then sell the house and we could let them stay in the annexe and pay council tax etc.? We really want the house and want to explore all options before we make a decision to walk away.
HouseBuyer - 11-Apr-16 @ 11:02 AM
john the paint - Your Question:
I have planning to build an annex on the side of my existing house, question, if sold in the future can I sell it has a separate sale to my house and also is this a good investment

Our Response:
You'd need planning permission first. If granted you'd then have to register the property separately with the land registry .We cannot say whether this is a good investment or not as we don't have details of your location or the property etc.
AGardenBuilding - 15-Feb-16 @ 11:12 AM
I have planning to build an annex on the side of my existing house, question, if sold in the future can i sell it has a separate sale to my house and also is this a good investment
john the paint - 12-Feb-16 @ 10:45 AM
jono - Your Question:
I am wanting to build a 30 ft by 15 ft self contained flat to rear of detached garage. The house is detached sitting on over 296 square feet of land. It was have the 2 meter boundary around build which I should mention would be a brick construction. Be no more than 2.5 m high with flat roof. Would include wet room, kitchen and living room. Was hoping to eventually use the double stand alone garage as a bedroom and join the two buildings into one. If this would be allowed. i.More then willing to pay the separate council tax. Just so you have a clear understanding of where the house is situated I will explain detached house is situated on (right) end of street. the garage is to the right has a 5 ft path/walkway seperating house. Garden stretches right across back sort of rectangular in shape. To the right of garage there is also a five foot gap. Where it meets the brick wall end of road. Then there is a 12 gap filled with some trees then a main road. The out building would face the opposite direction of main road. And not be seen due to brick wall that separates garden from trees. My question I'd like to know is this achievable? What chances are that planning permission would be granted. It would not impede on neighbours either. Cheers john

Our Response:
As the new building would contain its own/separate living accommodation and facilities, you would probably need planning permission. Your local planning officer will be able to tell you if you simply sketch out your proposal.
AGardenBuilding - 2-Sep-15 @ 9:49 AM
I am wanting to build a 30 ft by 15 ft self contained flat to rear of detached garage. The house is detached sitting on over 296 square feet of land. It was have the 2 meter boundary around build which I should mention would be a brick construction. Be no more than 2.5 m high with flat roof. Would include wet room, kitchen and living room. Was hoping to eventually use the double stand alone garage as a bedroom and join the two buildings into one. If this would be allowed. i.More then willing to pay the separate council tax. Just so you have a clear understanding of where the house is situated I will explain detached house is situated on (right) end of street. the garage is to the right has a 5 ft path/walkway seperating house . Garden stretches right across backsort of rectangular in shape. To the right of garage there is also a five foot gap. Where it meets the brick wall end of road. Then there is a 12 gap filled with some trees then a main road. The out building would face the opposite direction of main road. And not be seen due to brick wall that separates garden from trees. My question I'd like to know is this achievable? What chances are that planning permission would be granted. It would not impede on neighbours either. Cheers john
jono - 1-Sep-15 @ 2:23 PM
@paolo - if he is converting it for a residential use he should have planning permission. Check the terms of the planning application & decision (you can do this online).
AGardenBuilding - 18-Jul-14 @ 11:25 AM
My nabour is converting hi garage at the end of his garden , we have rear acess he said its for family only.how can I make sure he does not use it to rent out to other people.
poalo - 17-Jul-14 @ 12:23 PM
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Latest Comments
  • Trine
    Re: Building a Home Annexe
    We have been renovating our house for last 7 years turning the 80's nightmare to a nice modern space. We've got bored and now want to sell…
    29 January 2017
  • AGardenBuilding
    Re: Building a Home Annexe
    Ernie - Your Question:I have a four bed house but all rooms are extremely small. The house was built as part of an estate in the 1980s.…
    17 November 2016
  • Ernie
    Re: Building a Home Annexe
    I have a four bed house but all rooms are extremely small. The house was built as part of an estate in the 1980s. The rooms are so small…
    16 November 2016
  • HouseBuyer
    Re: Building a Home Annexe
    My fiancé and I viewed a property and really wanted to purchase it. Fortunately prior to involving Solicitors etc. it came to light that…
    11 April 2016
  • jont
    Re: Building Regulations for Garden Structures
    Hi i live in a housing trust flat (bottom) my neighbour also! he has a12ft by 12ft outside my windows…
    19 March 2016
  • AGardenBuilding
    Re: Building a Home Annexe
    john the paint - Your Question:I have planning to build an annex on the side of my existing house, question, if sold in the future can I…
    15 February 2016
  • john the paint
    Re: Building a Home Annexe
    I have planning to build an annex on the side of my existing house, question, if sold in the future can i sell it has a separate sale to…
    12 February 2016
  • AGardenBuilding
    Re: Building a Home Annexe
    jono - Your Question:I am wanting to build a 30 ft by 15 ft self contained flat to rear of detached garage. The house is detached sitting…
    2 September 2015
  • jono
    Re: Building a Home Annexe
    I am wanting to build a 30 ft by 15 ft self contained flat to rear of detached garage. The house is detached sitting on over 296 square…
    1 September 2015
  • AGardenBuilding
    Re: Patio Awnings and Canopies
    wooz - Your Question:Hi do I need planning permission for sun awning canopiesOur Response:It dep
    1 September 2015
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