Anyone done a mansard loft extension recently?

[Janegilroy]

We have a terraced house with the kind of roof that would really only work as a loft extension if it was a mansard. Recently a few mansard loft extensions have been approved on our street so we’re thinking we could get permission.

Anyone done one of these recently? Would love an idea of cost and how much space you were able to get. They are quite expensive it seems!

Could you put a note through the door of the houses who have planning permission and ask them, saying you are interested in doing something similar.
So much depends on the floor area, the number and type of rooms etc.