PD side extension and roof enlargement volume

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If I build a side extension on the gable end of a bungalow and its pitched roof extends up beyond the level of the eaves of the original building, does the extension's roof volume count toward the total roof enlargement volume of 50m3 allowed for a detached building under Permitted Development? See diagram.
 

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  • Side with example extn.pdf
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There is no 50m³ roof enlargement limit for a detached building within the curtilage of a house.
 
I don't think I asked the question properly.

The extension will not be a detached building it will be attached to the gable end of the existing building with its roof extending up above the height of the existing eaves. See attached drawing, top sketch.

My question is if the side extension roof abuts the the gable end above the eaves level does the extension roof volume count toward the 50m3 of total roof enlargement allowed under PD.

Another way of looking at it - Under PD I am looking to build a rear dormer on a bungalow that gives approx 40m3 of roof enlargement. Under PD I also want to build a pitched roof side extension on the gable end of the bungalow. Will the volume of the roof of the side extension be included in the max 50m3 roof enlargement allowed under PD? See attached drawing, top sketch.

I believe that if the extension were built on an elevation that had a pitched roof and the extension roof wrapped over the eaves level and abutted the existing roof then the extension roof volume would count toward the max roof enlargement of 50m3. See attached drawing, bottom sketch.
 

Attachments

  • Gable hip side extn sketch.pdf
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As long as the roof of the extension is not physically joined to the main roof, its volume should not be counted towards the volume of the roof enlrgement to the main roof. Note that the legislation refers to 'roof enlargement) ie roof in the singular.
 
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I think I'm getting there??? (me not you)

So for the purpose of PD and roof enlargement the gable end brickwork above the eaves is not considered part of the roof?
 
The volume is only counted if you form habitable accommodation within the new roof, and it will then be considered under Classes A and B. Otherwise under A and C so no volume consideration.

https://www.gov.uk/government/publi...nt-rights-for-householders-technical-guidance

'In order to be permitted development, a proposal must meet all the limitations and conditions under each Class relevant to the proposal. It is therefore essential that any proposed household development is considered in the context of the permitted development rules as a whole in order to determine whether it benefits from permitted development rights and therefore does not require an application for planning permission. For example, where a proposed two storey extension at the rear of a house has a roof that joins onto the main roof of the original house, the works will need to meet the requirements of both Class A (which covers the enlargement of the house) and Class C (which covers any alterations to the roof) in order to be permitted development. If the works also include the creation of a dormer window to enlarge the roof space, either in the extension or the original roof space, then they would also need to meet the requirements of Class B.'
 
HI, first post here and thread resurrection!

We have a similar situation with a dormer loft extension (just below 50m cubed) and a side extension with a pitched roof.

Our planning officer has rejected our application as they have counted the volume of the side extension pitched roof thus the total volume is too large for permitted development.

Whilst both Tony and Napolean have both helpfully suggested that this is not correct, can anyone actually point to where is says this in the guidance as I am struggling to see it, therefore leaving it "open to inerpretation"

I would be most grateful for your help.

Many thanks in advance!
 
Hi Atul- I have quoted the guidance above. Link here https://www.gov.uk/government/publi...nt-rights-for-householders-technical-guidance

That section is at the top of page 9.

The side extension roof volume should be included in the calculation if it forms habitable space. If it is separate to the main roof and does not form habitable space it should not be counted. To be fair this is a bit of a complicated point so the planning officer may not be aware of the distinction.
 
Thanks for the fast response.

Is this the part you are referring to?

"For example, where a proposed two storey extension at the rear of a house has a roof that joins onto the main roof of the original house, the works will need to meet the requirements of both Class A (which covers the enlargement of the house) and Class C (which covers any alterations to the roof) in order to be permitted development. If the works also include the creation of a dormer window to enlarge the roof space, either in the extension or the original roof space, then they would also need to meet the requirements of Class B."

I have to admit that I have read it a number of times and am a bit lost as to how it applies to our situation. Can you walk me through your thinking please? Is it saying that it only has to meet class A and class C if it joins the main roof?
 
The guidance explains that a particular extension may have to comply with the restrictions in multiple classes.

I don't have full details of your situation but in general the roof volume will only need to be considered if it provides habitable space within. Is the roof just a roof space or is it part of a loft conversion / habitable space?
 
hopefully this will help....

we have a semi detached house. We proposed 1) a single storey side extension that has a pitched roof 2) a rear extension with a pitched roof 3) a dormer loft conversion. Only the dormer will be habitable roof space, the side and rear extension roofs are not habitable and will just be voids.

nb: the rear extension involves replacing the small hip roof structure of an original scullery at the back of the kitchen. This will form part of (2) the rear extension.
 
Hi Atul I'm the original Post starter but your questions are relevant to my as yet unbuild and undecided project.

What I found out was:
  • If your rear extension touches your side extension, i.e overlaps even by the smallest (mere mm), then it will not be permitted under PD.
  • If the dormer roof height is over 4 metres and any part of it, including its roof, touches or is too close to any part of any structure that is not part of the original building it will not be permitted under PD. This because the regs/council will/may consider the 2 structures to be one and PD only allows roof heights up to 4 metres (unless the regs have changed since I last looked).
  • If the dormer roof height is over 4 metres and extends into or touches the side extension then it will not be permitted under PD, for the same reasons as above i.e. 4 metre height restriction.
What constitutes "too close" and "touching" appears to be down to the local planning authority. If there is any doubt I suggest you make an application for a Lawful Development Certificate and be real honest about the position of things but re-reading your post it looks as though you may have already done that.

For my part I hope I'm wrong and/or the regs have changed coz then I can get building what I want:)

Edit
  • Just a thought - The local planning authority may well include the extension roof voids in the 50m2 calculation if the voids are accessible from the extensions accommodation side walls, i.e if you use the areas as enclosed cupboards with doors rather than open loft space accessed via tool fixed removable panels because the cupboards may be considered as accommodation.
 
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