This question comes up a lot, and depending on where you get your information from, can lead to some wildly differing answers. It usually leads to a follow-on question which we shall also look at. Overhanging branches can cause real problems, not just in the practical sense, but also in the legal sense when the two parties cannot agree and fall out ending up in a legal dispute. If handles the right way though, this fairly simple matter should be able to be resolved quite easily so let’s take a look.
The very short answer to this in Adelaide and all of South Australia is the tree owner themselves. When this is a neighbour then this is fairly straightforward to deal with, but when it comes to land owned by a company then things can be a little more complicated to deal with.
Neighbours: When your neighbour owns the tree then it’s a simple (or not) matter of popping by and talking to them about any potential issue, like seeding (trees will drop their seeds in great quantities in order to populate nearby areas), fruit, leaves, branches coming close to structures like buildings or power lines and also tree roots can cause problems with plumbing and drainage. the biggest problem is branches falling and causing damage to buildings, fences, plants or worse – people. If any of these problems are occurring it is the owner’s responsibility to trim or prune the tree. This, however, is when problems usually arise.
Company Land: While sometimes being harder to track down or contact, companies are generally more responsive to these types of issues as they have responsibilities and tend not to take things personally. Plus they should also have the budget for this type of thing and would generally want to avoid any legal dispute for sake of their reputation.
So, this lets us to the follow-on question:
The short answer is yes, though this does vary somewhat from state to state they hinge on whether or not tree trimming, pruning or lopping for the type in question is legal or not or requires a permit. For most common trees you won’t require either, but it is your responsibility to check. Also, it would be best if you informed the tree owner before you do. Most people will ask their neighbour to deal with the tree themselves, but often it won’t get done because they aren’t able to or don’t want to deal with the cost. This can also sometimes apply to companies too.
Whilst you are perfectly within your right to recoup the costs from your neighbour and any decent one should offer themselves if they are unable to deal with the problem, but in most cases they won’t. This comes down to the common law of nuisance which puts you in the right, but we seriously don’t recommend doing this as it just isn’t worth it. If you are a capable gardener and know how to prune the offending tree correctly and have informed the tree owner, then you can cut it back to the boundary line as long as there is no local law against it. For the removal of whole branches, we strongly recommend you don’t do this and just contact your local qualified arborists instead. They can also help advise on the best course of action as well as give you a quote on the job to be done safely and legally.
So the owner of the tree is responsible for the overhanging branches (or roots) and you are generally within your rights or cutting them back to the boundary line yourself (or having an arborist do it) but only if you have informed the tree owners themselves. Recouping costs will almost certainly lead to disputes and we generally advise against it as even though the law will be in your favour, the time, stress and initial costs of recouping won’t be worth it. Reaching any agreement like 50/50 is a win but there’s certainly no harm in asking. Companies are more likely to say yes, and most neighbours should also contribute too.