Do I need planning permission or not?

[MakeTeaNotWar]

Feel like I'm being really dense but I'm not clear on whether we need planning permission or not for our proposed loft conversion.

We live in a semi-detached bungalow that has a large unconverted loft. By adding a dormer, we hope to be able to add 3 additional bedrooms.

The existing loft space is 50 cubic metres. By adding a dormer, we would increase this space by a further 45 cubic metres. Google tells me that only by increasing the space by more than 50 cubic metres would I need planning permission so I thought I wouldn't as we are only adding 45 metres cubed of new space. But a surveyor I spoke to seems to think that we do - he makes it that we are adding 95 metres cubed to the existing living space ie downstairs.

So confused - can anyone shed any light?

Your best bet is to ring your local planning department for clarification.

The planning portal reckons that the 50 cubic metres is additional volume on the original space. See here

So your 45 should be within pd rights. Best to get a covering certificate tho even if you dont need planning it saves a lot of trouble esp if you ever have to sell.

Ring up your local council and ask their opinion. Some Councils will actually send someone round for free inspection.

The other thing to think about, if you have not already got a builder, is to ask the local trading standards dept for a list of their approved builders - it can help you avoid cowboys. The last thing you want is Roy Rogers riding Trigger around in your loft... unless that is the purpose for which you are converting the loft.