Change Roof type (flat roof to pitched & skylights) after planning approval?

16 May 2021
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United Kingdom
Hi. Am I allowed to change the roof shape for a 6m rear extension after planning approval (neighbourhood consultation)? Can we change the type (shape and size) and no of skylights and the roof pitch (say from flat roof to pitched roof instead) as long as we stay within the limit of the permitted development guidelines of 4m height of ridge and 3m eaves. Our house is end of terraced for a block of 3 houses and we are not sure on the roof shape as yet but need to submit asap. We are not sure if we should stick with 3m flat roof or go for pitched roof with upto 4m ridge and 3m eaves (in terms of cost and neighbour objections).

Many thanks in advance!
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I will qualify my answer by saying prior approval larger home extension applications are not my strong point.

So I would say technically as long as proposed alterations are still within the permitted development limits then you should be OK. BUT, if you submitted any plans or details which showed a flat roof or gave a lower roof height then the neighbours could argue that they were given inaccurate information and might have wanted to object if they had known the extension was going to have a 4m high pitched roof. I don't know if they would have any legal basis to object retrospectively or whether the council could enforce the original application so you could be opening a can of worms.

Hopefully someone cleverer will be along to give a definitive answer but if that doesn't happen I would at least talk to neighbours to see how they would feel about a change to the roof. Or, if like me you just put the bare essential information on your application, so just a location and site plan showing the position of the proposed extension with maximum dimensions of the extension and the changes do not exceed those dimensions then I cannot see a problem.
You would need to submit a revised PA application as what you end up with isn’t what you currently have sought PA for. The description of the proposals on PA applications are quite detailed too so wouldn’t tie up with a revised roof design.
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If you read the text of your approval notice it should say something along he lines of

".... hereby confirm that their prior approval is not required for the proposed development at the address shown above,
as described by the description shown above and in accordance with the information that the developer provided to the local planning authority"

So if you alter the work that statement becomes invalid, along with the letter, and a prior approval may be required (ie a planning application). So there needs to be a completely new application for the new design.

However, if your approval letter contains something like this ...

"It is a requirement of the above condition .... that the development shall be carried out in accordance with the details approved by the local planning authority, unless
the local planning authority and the developer agree otherwise in writing."

there would be scope for a simple rider or alteration to the design.

But, as fees are now chargeable for this scheme, the Council may be minded to want you to re-apply and pay them some money.

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