Tree Root Damage and Buildings
There are two types of damage trees may cause to property, namely direct (through physical contact) and indirect (subsidence).
This results from the pressure that may be exerted by a tree's roots or trunk (Macleod and Cram 1996).
This pressure can affect lightly loaded structures such as garden walls, driveways and paved surfaces but rarely affects heavily loaded structures such as houses.
This results when tree roots extract moisture from shrinkable soils, usually clay (Biddle 1998) and if the foundations of the building are inadequate. This may result in subsidence and cracks appearing in the building.
If cracks appear in a building and it is thought that a tree on the neighbouring land may be to blame, then the tree owner (or their insurer) may be liable for the cost of repairs. In order to demonstrate liability, evidence should be provided beyond a reasonable doubt that the tree is, in fact, responsible. It may also be necessary to demonstrate that the damage was reasonably foreseeable and that the owner should have taken action to control or remove the tree.
It should be noted that there is a normal seasonal drying and wetting of soil and also that heave may be a possible consequence of removing the tree, as the moisture previously removed by the tree swells the soil.
An owner is not obliged to control or remove a tree that is implicated in causing subsidence. However, a failure to do so may result in liability if it is later proved in court that the tree was a contributory factor to the subsidence.
Nevertheless, before agreeing to fell the tree, your neighbour (or their insurer) should provide reasonable evidence that your tree is the principal cause of the subsidence.
For specific advice, with respect to the law, please seek qualified legal opinion.
APN 11 Trees and Hedges in Dispute