Summary of this section
Encroachment into the airspace – damage presumed – tree root subsidence a different category of nuisance regulated by the ‘Leakey’ duty (‘category 3’)
Eaves and other nuisance by encroachment
Where an artificial object is erected which protrudes over, and therefore encroaches into, a claimant’s property, then a nuisance will be presumed. The damage may be rainwater which drops on to the claimant’s land, the inability to build right up to the boundary or the mere fact that the claimant considers it an interference with the use and enjoyment of his / her land. In any event, the courts will infer the existence of a nuisance. It is necessary, however, to plead the existence of the nuisance. (See Fay (1845).)
This is a category of nuisance in its own right and is also applied to the boughs of trees.
As to the roots of trees and other flora (vegetation below ground), it may be that as a matter of fact there is a form of encroachment, but these actions are to be distinguished from ‘category 4’ claims, and are actionable only where some physical damages can be proved to have been the result. This is usually because the defendant has failed to take steps to control the roots, the consequence of which has been some damage (typically subsidence). Such claims are regulated by the principles which apply where there is a measured, ‘Leakey’, duty of care (‘category 3′).
In Williams (2019), the view was taken that cases which previously decided that an encroachment into the airspace constituted trespass had not been properly decided.