Hi. I have permission for a 3m extension and want to start the project. However, I only want to dig footings at the moment, so I don’t lose my planning permission.

The edge of my patio is 2.8m, and the patio is 1m drop from the floor of my house.

Do I need to dig foundation so it is exactly 30cm either side of my 3 metre from existing wall of house, meaning I would need to dig under the patio? Or can I just dig the footings where I have space?

Also, if I intend on making the extension a little longer, such as 3.2 m, is this acceptable or do I need permission?