I discovered that in a house in Penzance belonging to my then girlfriend's mum. They asked me to store some stuff up there and I was shocked to see that I could roam freely up and down the communal attic.
Apart from the potential for theft, voyeurism, and general dodginess... the thing that struck me was that it was a huge fire hazard! If one house caught fire there was an obvious risk that the flames could quickly spread to the whole terrace via that attic space.
That has happened many time
I had a survey done on a house I was renting and wanted to buy
it was semi detached - used to be a counsel house built in the 1940s/50s I reckon
The surveyor said I would be best to have the dividing wall extended up to the roof properly so I looked
tIt was about a foot high - which explained all the dead flies in the house when I moved in - they had had a nest nexy door and called in the exterminators - the flies must have migrated across the two houses
The surveyor said that a lot of mortgage companies would insist on the dividing wall being extended as a condition of the mortgage