Any regulations covering a lean to?

[Scout]

Hi does anyone know if any building or planning regulations/permissions are required for building a lean to on the back of a terraced house?
My neighbour has put up a rather unsightly lean to without saying a word and whilst I'm not out to cause trouble I just wondered if he is allowed to do this?
If you can imagine a typical terrace house with the bit extending out the back half the width of the rest of the house. He has then filled in the side space with a lean to sitting on the boarder wall (which is just on his side) from the back of the main house all the way to the end of the extending bit.
The lean to is only made from rough sawn timber and polycarbonate fluted sheeting and it sits on top of the existing wall which I'm not convinced is all that solid! He has put a gutter along the edge to catch water off the roof but this then just goes into a large plastic dustbin stood at the end and sticking out partway across the gateway that is my access (he has issues with me having access so I avoid using it).

I am just interested as to whether he is perfectly entitled to have build this or if he should have sort permission as I know nothing about these things!
Thanks

[Someone-Else]

Why not call your local BCO and ask them? (Since it is they who say yes or no)

[big-all]

is it less than 2.5m
https://interactive.planningportal.co.u ... se/outside

[Scout]

I’m concerned about making waves and causing myself more problems that why I am interested in other people’s thoughts and options first.

I doubt it’s 2.5m high at the low side of the pitches roof but could week be where the roof joins his house wall.

[big-all]

read through this lot
https://www.planningportal.co.uk/info/2 ... extensions
although as its a temporary structure will be a bit different