Side extension under permitted development rights

4 Feb 2017
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United Kingdom

Wondering if anyone knows the answer to this...

Can you build a single storey side extension under PD rights on a house which has had a double storey side extension already built/approved under planning permission?

Original dwelling house as it stood in 1948 was 12 meters wide, it was then extended by 5 meters with a 2 storey side extension quite recently via planning permission (making it 17 meters wide).

Can I then add a single storey side extension (half the original house i.e. 6 meters) on top of the 17 meters created under planning permission to make it 23meters wide?

It is not clear from the technical guidance if the term "enlarged part of the dwellinghouse" includes the existing 2 storey extension or only references the proposed single storey extension.

If it includes the existing 2 storey side extension then I can only extend under PD rights by single storey of 1 meter wide (instead of 6 meters)

See guidance below:

Development is not permitted under Class A if:

"the enlarged part of the dwellinghouse would extend beyond a wall forming a side elevation of the original dwellinghouse, and would –
(i) exceed 4 metres in height,
(ii) have more than one storey, or
(iii) have a width greater than half the width of the original dwellinghouse

Thanks for any input.
Last edited:
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If the proposed extension is on the opposite side of the house to the two-storey extension, then yes.
If you mean extending an existing extension further sideways, then - normally - it would not be p.d.
However, there has recently been a High Court case on the interpretation of the words "original dwellinghouse" which for the moment overturns the established rules - google 'Hilton v DCLG' for interesting commentary.
And when you guys get a job on your desks what will you recommend to your clients? Are you tenacious enough to push for this yourselves, if so how?
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In this instance, I think Hilton is very relevant!!
I'm inclined to agree with fmt here; if we do this every day, we get to know the ropes, as it were.
But no matter how hard we might try to persuade a client that he can give 2 fingers to the council, I would not
expect a client to argue this with them. In practice, neither would I spend time arguing with them when it's easier for the
client to pay £172 for his bit of paper.
But if it was a job on my own house - that's a different matter and I would be waving Hilton at them:LOL:

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