Loft conversion with existing two storey side extension

[Rossdamien]

Hi, just looking for some advice on permitted development rules and how they apply to a previously extended property.

I am looking at doing a hip to gable loft conversion with a rear dormer. The house is a 1930s semi and has already had a two storey side extension with the roof on the extension being stepped down to half the height of the original roof. Two architects have told me that because of the previous extension I would need planning permission and would be unlikely to get it for the dormer, but I am not convinced that is correct.

The plan would be to do the hip to gable conversion over the original external wall leaving the roof over the extension sloping up to the new gable end.

There are a couple of picture attached that I hope will make it a little clearer.

My understanding of the PD rules is that as long as the volume of the resultant external roof space isn’t increased by over 50 cubic meters when compared to the original roof (plus a few other conditions) then it falls under PD.

When calculating the additional volume I believe I can simply take the additional volume created by the dormer and new gable end vs the original roof and add on just the part of the existing extension roof that remains outside.

I assume I don’t need to include the additional roof space on the existing conservatory.

Based on my measurements, this would result in a total increased volume right on the PD limits, but I am confident that I can tweak the size of the dormer sufficiently to get it under the limits and would apply for a certificate of lawful development.

I am just a little concerned that two architects would fail to advise that that would be the case and suggest that full planning would be necessary.

Any advice would be gratefully received.

Thanks in advance.

 

[tony1851]

They are correct in that full planning permission would be required if you did a hip-to-gable in that position, because the new gable would
impinge on the roof of the side extension.
The only way you would get a permitted development flat roof dormer is to have the dormer only the width of the existing ridge, which would make it about 2.5-3m wide.
It would also be difficult to get the new stairs in if you were planning to go above the existing stairs.

 

[Rossdamien]

Thanks for your response tony1851.

 

[Leofric]

I am just a little concerned that two architects would fail to advise that that would be the case and suggest that full planning would be necessary.

- because they were right and you were wrong, as Tony has explained.

Any advice would be gratefully received.

Take the advice of one of the architects you consulted on what to do next if you want to proceed further with the scheme.

 

[Rossdamien]

@Leofric I’d also like to say thank you for your input too, although it didn’t add much other than a condescending tone.

But by way of an update, rather than just accept the view that full planning would be required I challenged the architect to explain exactly where the legislation stated that this would be a problem. He couldn’t and on that basis changed his view and submitted an application for a LDC.

My local council have since confirmed that this is lawful development and their only concern was that the total volume limit is close, due to the volume of the roof on the existing ground floor extension, which they insist must be included.

Whether I am correct, or the council are misinterpreting the legislation in the same way as I have, I don’t know, but I am looking forward to getting on with the build in the near future.

 

[Leofric]

@Leofric I’d also like to say thank you for your input too, although it didn’t add much other than a condescending tone.

Good to see my comments are appreciated.

My local council have since confirmed that this is lawful development and their only concern was that the total volume limit is close, due to the volume of the roof on the existing ground floor extension, which they insist must be included.

So what are the council actually saying,seems a bit confusing

 

[tony1851]

There is often confusion on the roof volume, even among planning officers.
There are some appeal decisions which say that the roof of a separate extension does not count towards the 50m³ limit for a roof enlargement, while other inspectors have declared that it does, even for eg. a ground floor extension which has no contact with a dormer.
Until this issue gets tested in a court, it will be one of the many grey areas of the p.d. rules.

 

[Rossdamien]

@Leofric the council are saying it is lawful development and have issued the lawful development certificate.

They had initially suggested that there may be an issue with the total volume, as the architect had drawn the roof on the ground floor rear extension incorrectly. He didn’t believe that it should be included as part of the increase in volume and therefore hadn’t paid as much attention to it. After submitting amended drawings showing the roof on the existing extension correctly, they were happy that it was PD.