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Converting Two Houses Into One

By: Chris Hogan MSc - Updated: 4 Oct 2017 | comments*Discuss
Converting Extension Houses Planning

Converting two houses into one is sort of an extension but unless you do actually build an extension at the same time, you don't need planning permission. This is because all the work is internal and for planning purposes it is not considered to be development.

Check Planning Carefully

That doesn't mean you can just go ahead and do it though, there's a lot more administration to consider. There may be other rules that apply, listed building consent, for example, or you may be in an area that has blanket restrictions like a conservation area.

There are implications for building control as well. You will need to combine the electrical and gas supplies into one for safety reasons and that will involve getting building regulation approval, although properly registered professionals can self-certify their work. Fire safety regulations may compromise your plans too.

Look at Converting to Create a Coherent Whole

Still if converting two houses into one gives you the space your family needs there's no reason not to go ahead and do it. Try to look at the big picture though. If you just knock one hole through and leave everything else as it is you will have a lot of small rooms. It's a shame to miss the opportunity to create something that is greater than the sum of its parts.

At it's simplest you can just knock a few openings through between the two properties. This is much easier if the properties' staircases are next to each other, you may even be able to get away with simply knocking though on the ground floor and upper landing. It's not going to hurt having more than one bathroom in the house with our current preoccupation with having a bathroom for virtually every bedroom.

Real Life Example

In fact the houses we live in now is the simplest possible conversion. The terraced house at the front has the lounge, four bedrooms and one bathroom over three floors. The other house to the rear at right angles (previously an unattached barn) has a dining room and kitchen with one large bedroom and a large bathroom on the second floor.

The houses were joined by knocking one hole through the lounge into what is now the dining room, and that's it. There are two staircases but it works because each side has a bathroom as well as bedrooms, otherwise people would be running all over the place. One day a better job will be done but for now it works.

Long Term Financial Considerations

There are plenty of financial considerations too. Buying the house next door may, in a depressed market, be cheaper than building a two-storey extension. But the one house that you create is likely to be worth a lot less than the two separate properties, unless you have bought two very small properties in a road of larger, more expensive ones.

From a pure financial gain point of view the sensible option is likely to be converting the two houses into one and then converting them back again for resale later on. This actually flies against the advice above, but if this is the plan then you are unlikely to spend time and money, for example coming up with a new design that amalgamates the two facades, if in ten or twenty years time it's all going to need to be undone.

Take Independent Advice

You should definitely take independent financial advice about converting properties like this as well. You will have cheaper council tax for the one larger property but there may be implications for capital gains tax in the future. These might make it worthwhile keeping the properties separate for council tax purposes.

Thee issues will be different for every single case so it's impossible to give guidelines here, independent advice on a case-by-case basis is necessary.

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The government will hit you with the Stamp Duty Surcharge when buying the second property and although logic suggests you can get a refund once it's one property the government have created an example for this on the refund criteria. You currently cannot claim a refund so will pay 3% extra stamp duty on the full purchase price of the second home. Won't be voting Tory at the next election and I live in a marginal seat. So much for less red tape with the tories!
JBye - 4-Oct-17 @ 1:08 AM
Pat - Your Question:
We live in a detached, very old, grade 2 listed house that at some point well before our tenure, was divided into a main house and a 'cottage' - effectively 2 homes. We would like to re-convert it back to one house. Your article talks about getting advice - but which profession/authority should we approach? Advice appreciated.

Our Response:
You will need to contact your local authority planning department for a pre-application discussion about it and English heritage will also expect to be consulted.
ExtensionBuild - 3-Jul-17 @ 2:52 PM
We live in a detached, very old, grade 2 listed house that at some point well before our tenure, was divided into a main house and a 'cottage' - effectively 2 homes. We would like to re-convert it back to one house. Your article talks about getting advice - but which profession/authority should we approach? Advice appreciated.
Pat - 3-Jul-17 @ 9:46 AM
I was after some advice, we own a property that has an attached annex, this is recognised as a separate dwelling house (own council tax, address, gas and electric supply), a couple of years ago the previous owner had lawful entitlement approved for this to be recognised as a separate dwelling house.My question is what are the implications of creating a single dwelling house out of the main house and the annex... if it helps we have the ability to convert a barn into another annex if that were necessary....
Duncan - 26-Apr-17 @ 9:32 PM
I live in a one bedroom semi detached bungalow and next door has come up for sale. If it was financially possible, I would love to buy it and create one home. Has anyone else actually done this. Interested in ideas.
Mik - 7-Apr-17 @ 1:09 PM
No comment - I just want to red the rest of the discussions
Moss - 25-Mar-17 @ 3:40 PM
We live in a semi detached house and got it for a very good price about 4years ago. The house next door has come up for sale and we are considering buying it and having one detached house. We have Looked on the market and it just seems that for in our area and a house the size it would in effect be; This seems the best option. We have rennovated our current house. There is the option of an extension but this seems so much upheaval and we wouldn't really gain a lot. We are desperate for more space. Has anyone done this? Would love some feedback!
Kturg - 6-Mar-17 @ 10:52 PM
We have bought 2 terraced houses and plan to knock through to make 1. We are not changing the footprint of the building, only changing the internal layout. I just spoke with the Planning Department and they told me that recent legislation changes mean that we do now need planning permission. Does this differ around the country? Are you aware of such legislation? I knew we'd need building regs but was advised planning would not be required. Thanks, Annie.
Annie - 2-Mar-17 @ 3:24 PM
I am buying the house next door to me, it's a semi detached and I live in the other half of that semi. Although undecided, I may be converting to 1 house. If I do go ahead with this and inform the council that it is 1 house, do I have to prove to them by way of a single opening and is there a time limit on this? Many thanks
KBabs - 2-Feb-17 @ 12:44 PM
I am looking for some advice please. I built a games room/ home office /gym in a separate detached building in the curtilage of my house. It complied with the planning criteria for permitted development and I applied for and received a certificate of lawful development. 3 years later I want to sell my house but retain the ancillary building. Is there any legal requirement that the main house and the ancillary building cannot be separated? Thanks for your comments and opinions.
Shay - 27-Dec-16 @ 12:59 PM
My husband and I bought a one bedroomed flat and because it was small we bought next door and put a doorway inside and used it as one property. We have now put them back into two and are selling one, will we be liable for capital gains?
Georgie - 5-May-16 @ 9:18 PM
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