Permitted Development Question

18 Mar 2012
Reaction score
United Kingdom
I've been using the forum for some time now, and found the advice very helpful. This is the first time I've needed to post a question.

The house has never been extended, and the single storey annexe was built at the same time as the double storey section of the house - it's part of the original house.

My question is whether I can add a 1st floor on the single storey annexe through Permitted Development?

I'd be looking to keep the extension in-line with the double storey section of the house at the front, and possibly at the rear too.

Any advice appreciated.



Sponsored Links
Not if it comes within 2m of a boundary.
Thanks for the reply Jeds.

There are no boundaries within 2 meters of the single storey section of the house that we want to build on top of.

The closest boundary is 6 meters.
Sponsored Links
It must be a side elevation then. Side extensions under PD are restricted to single storey.
Whichever way you look at it, it's on the side of the house. Yes it's above an original single storey section but that's a single storey section which is on the side. If you build on top of it you would be outside the PD height limits.
Call the local authority and book a pre-planning meeting. There is no charge. Take the drawings and explain what you want to do. Whilst you will not get a definitive answer you will be reasonable advised as to PD or the likelihood of planning permission being granted.
I think it's more like this clause that clobbers you, not page 20:

"the enlarged part of the dwellinghouse would extend beyond a wall
which -
(i) fronts a highway, and
(ii) forms either the principal elevation or a side elevation of the
original dwellinghouse
This restriction means that any development to enlarge a dwelling house that is in front of a principal or side wall that fronts a highway will require an application for planning permission. "

Essentially the question is "do you want to alter the shape of your house so that any of its walls are closer to a road?"

And sadly, sticking an extension on top of your annexe does mean that one of the walls of the house is closer to the road (the wall of the second storey :/

Still, you've got some good scope for adding a rear extension, and if you want a two storey rear extension you could always dig a big hole to put your cinema room/kids play room in.. Neighbours would probably thank you for it too ;)
Thanks for the comments. The issue with my local planning authority is that although they claim to offer an informal drop-in advice service, when you get there, they ask you to email your details, and then get pushed through the formal application processes.

I'm happy to do this, but want to get a clear understanding of the PD rules first, hence my post here.

Cjard, you present an interesting point on. My understanding was that the Principle and Side Elevations of the building refer to those of the 'Original' building's footprint. Now you have me questioning myself. I wonder if your interpretation is correct!

I do hope not :eek: :LOL:

One of the corresponding images from the section of the Technical Guidance that you refer to is this one:


The white boxes represent extensions that would not be allowed under Permitted Development.

Page 20:

"The term “more than one storey” applies to the part of the house being enlarged through permitted development. This could either be a two storey extension to a house, or might comprise the addition of a storey onto an existing part of the house - for example, the addition of a second storey onto an existing single storey part of the house. The enlarged part of the house must not extend beyond the rear wall by more than three metres if it is to qualify as permitted development."

It'll be interesting to see how my LPA interpret all of this.
We've long held (here) that if PD is used to add an extension on top of an existing extension, then the whole lot (both extensions) must be within the PD limits. i.e. if you got planning for a massive ground floor extension, then wanted to PD a small extension on top of it, you couldnt because the massive extension is beyond the limits of a PD ground floor extension

In terms of PDing an extension on top of an existing single storey part of the original house, I don't think there's a problem so long as the PD limits and limitations for second storey extensions are respected. The things I believe to be the problem for you are 1) the highway - a side wall that fronts a highway may not be moved closer to the highway and 2) side extensions must be single storey (page 23 - this is less restrictive than point 1 though)

The reason I say this is that elsewhere in the guidance and the law, provision is made for irregular shaped walls (such as bay windows) in that all faces of the wall are principal and may not be projected forwards. Page 14. The examples drawn are top down but logically they can accommodate situations where a house has a bay on the downstairs only: you can't build the bay upwards because you;re moving the principal elevation of the upstairs nearer to the road. The top down examples wouldnt show this, but if a side profile of the house were shown it would include it

If you regard your conservatory as a massive bay window, fronting two roads, you cannot make the elevations above it go nearer to the road :/

Of course, you could install 20 feet of kingspan as external wall insulation, then hollow it out to create a room :)

That said; why not just go for guidance from the planners? It's free and you get to psychologically profile the person who will decide your case, so you might be able to work out what they like and hate and then include some of their ideas (showing you listened to the guidance) and justify other ideas that deviate from the guidance

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links