Air Rights and Flying Freeholds
You can own a room that hovers over your neighbour's property. It's called a 'Flying Freehold' and it is a notorious nightmare for mortgage lenders.
Property ownership usually extends directly downwards to the centre of the earth and upwards into the sky. But in historic UK towns, hundreds of years of unregulated building have created legal anomalies where property lines intersect in mid-air.
The Flying Freehold
If a room of your house extends over a passageway owned by your neighbour, or over a room in their house, you own a 'Flying Freehold'. Conversely, if your neighbour's room hangs over yours, it's a 'Creeping Freehold'.
While historically interesting, they are a nightmare for conveyancers. The problem is enforcing structural maintenance. If the neighbour below you refuses to fix their crumbling walls, your 'flying' room could collapse, and you have limited legal power to force them to conduct repairs. Because of this massive structural risk, many high-street mortgage lenders will flatly refuse to lend on properties with significant flying freeholds.