Help! - Prior Approval - 8m - Larger Home Extension Scheme

23 Aug 2021
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United Kingdom
We have an existing ground floor and first floor extension to the rear of the house, see plans attached. We would like to apply for the Prior Approval larger home extension scheme to get a 8m extension on the ground floor.

On the proposed plans attached we have removed the first floor existing extension (boxed red on the existing plans) as our architect does not know whether we are allowed to retain it under the Prior Approval scheme. The question is:

1. Can we retain the first floor existing extension on the Prior Approval application? OR
2. Do we have to leave it removed and apply for it via planning later?
Prior app - Existing Rear.jpg
Prior app - Existing Side.jpg
Prior app - Proposed Rear.jpg
Prior app - Proposed Side.jpg
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You can only extend from the original house wall. So, for example, if you have a 3m extension your maximum additional extension would be 5m.
Thank you for your reply John. We are still wondering if we can we retain the first floor existing extension (box in red) on the Prior Approval application?
So you'd remove the ground floor extension and replace it with an 8m extension and rebuild the dormer? Or do you mean remove part of the existing extension (leaving the dormer in place) and adding an extension taking you up to 8m?
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We would like to leave the dormer in place and extend up to 8m in total, (i.e. the current extension is 4.5m and we want to add another 3.5 to it), can we do this with the Prior Approval application?
I think the OP is asking whether the following is permissable under the Class A.4.


My understanding of the Act and Technical Guidance is that it is - but, like your architect, I'm not certain. A Certificate of Lawfulness for Proposed Use or Development might be a sensible way to go - although, thinking about it, I'm not quite sure how that works in this instance!?!
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Thank you very much Nakajo for illustrating our position more clearly and thank you for your advice, we really appreciate it.
I would submit a prior notification for just the 3.5m addition - with first floor remaining as existing.
You can't use the prior approval process (which is intended for a single story only) to join to another addition that makes the "enlarged part of the house" a two storey addition - as this would not be permitted development.

There was a thread about something very similar a good while ago
This is from page 18 of the Technical Guidance (https://assets.publishing.service.g...e/830643/190910_Tech_Guide_for_publishing.pdf).

I appreciate the Technical Guidance is 'guidance', not 'law'; nevertheless, the guidance is used by LPA's to assist with their interpretation of the Act...


According to the guidance, this 'piggy-back' extension is not PD not because it attaches to a previous extension, but because the rear wall is more than 8m from the rear wall of the original property.

The inference then is that subject to the distance limitation, this is PD under the Prior Notification scheme.
Thank you all for your replies. We have consulted 3 architects and 2 planners as well as your combined wisdom and decided to apply for the 8m under PD - prior approval scheme and remove the 1st floor existing extension. Then under planning reinstate the 1st floor. Thank you all again. We really appreciate all your replies.
Just apply for full planning. It's not a big price to pay for the peace of mind that you are doing it right. I think I paid £170 a few years ago for our extension - could probably have done it as PD, but wasn't worth the risk.
Nakajo, thank you again. To answer your question re: refusal of 1st floor, as it was previously granted and all the other neighbours have an extended 1st under planning it should be ok (hopefully, fingers crossed). You are also right, we would not get 8m ground floor extension under planning, we already tried.

Djangobanjo, thank for your reply too, as Nakajo said planning officers would not grant 8m extension, so only choice to go under permitted development via prior approval larger home extension scheme.

Thank you all for all your replies, have been very helpful!

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