From at least 1285, but possibly much earlier, the Latin maxim Cuius est solum, eius est usque ad coelum et ad inferos governed the ownership of airspace and stratum below the surface of a property.

Translated, it provides "the person who owns land owns it from the heavens above to the centre of the earth below".

That view of the law was maintained in NSW until as recently as 1989 when the Supreme Court held that a trespass to airspace over land could occur only where the incursion is of [such] a nature and at [such] a height that it may interfere with the occupier's ordinary uses of the land.'

Despite the tempering of landowners' rights to the airspace above their property, property developers in Sydney's CBD have reportedly started paying big money to buy access to airspace above their neighbours' properties.

Two examples the Daily Telegraph recently reported that developers had bought:

  • a significant portion of the airspace above St. Stephen's church; and
  • 12,000m2 of the airspace over Hyde Park Barracks.

The US President Donald Trump is also reported to have been an early adopter of the fad, purchasing the rights to the airspace above the buildings situated around Trump Tower in New York City, apparently to avoid the sting of city building codes that would have otherwise prevented the construction of such a large building on a small city block.

In Australia at least, the airspace "purchases" are likely to have been undertaken by way of easements acquired by developers over the neighbours' land below, probably as easements for overhang.

Easements are essentially rights attached to a piece of land that give the owner of that land some right to use other land belonging to another person. A typical example would be an otherwise landlocked property possessing an easement over neighbouring land to use a driveway in order to drive between the landlocked property and the street.

Essentially, they operate as an exception to the rule that a person's property rights are absolute and come in many forms. Whether any easements exist should be fully investigated before a property is purchased and legal advice should be obtained as to what another person might be entitled to do with your own property. Likewise, legal advice should be sought if a neighbour approaches you seeking an easement over your property. You never know, they could be planning to build a tower over you.

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