Planning Permission, Permitted Development, Certs of Lawful Development – Loft Conversions Explained!

OK, so I asked my previous architect for a quote to do plans for my loft conversion and they came back with a figure of around £2500. This seems a little steep.

The quote was for the initial plans (pretty pictures etc.) that go to the local planning department, the plans for building control, and engineering calculations, that are required to ensure that roof does not collapse.

I spoke to several builders, and all but one said “I will give you a quote when you have the plans”. The final builder said: “you do not need all those plans. The loft conversion will be under permitted development, so all you need is one set of plans with engineering calculations, and this can be sent to the council to obtain a Certificate of Lawful Development, and the same plans can be used by me (the builder) and building control”.

This made a lot of sense. And the price was £775, a saving of £1725, which is handy.


Permitted development rules allow most homes to build a loft conversion without the need to obtain full planning permissions – permitted development is really a way of saying, the planning permission is already on the house.

Councils will sometimes put blocks on permitted development (for example, I cannot convert my garage or carport, as the council want me to be able to park three cars on my property due to a small access road), but a quick phone call or email (I think I phoned the council and they emailed me back) and the council will advise if there are any restrictions in place.

My builder also said that he can start building on a 48 hour notice to the building department (building control) so as soon as my plans are ready (they were ordered last Monday, I think) I can send them to the council and be good to go!

The Planning Portal website also says: “It is not compulsory to have an LDC but there may be times when you need one to confirm that the use, operation or activity named in it is lawful for planning control purposes.”

Some builders will want to see one, as to start a job and then have to stop halfway because somebody makes a complaint is a PITA for all concerned. Best to have the paperwork handy!

Some resources from the government:

More like this in the Loft Conversion section

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