Neighbors have put up a canopy

Questioner

My neighbors have had a canopy built on the back of their house. All that was said was that they were going to put up a roof. It is now 12 cm from the property line. With a height of 2.40m and an extension of almost 3.50m. Now we are looking at a black and white section. Can this be done without a permit? And shouldn't they have specifically asked our permission? Is there anything that can be done about this?

Lawyer

Usually 50% of the back yard can be built on without a permit and one does not have to take into account the property boundary and the distances to be kept. The height of the extension also seems to me within the margin.