Neighbours will generally be required to contribute equally to construction costs for a “sufficient” dividing fence (determined by the existence or otherwise of an existing fence, the type of fence usual in the neighbourhood and the purpose for which neighbours are using their land). Owners wanting a more expensive fence will have to meet extra costs.
Owners will have to seek agreement from their neighbours before building a fence, even if they intend to shoulder the cost themselves.
City of Greater Geelong website has information on fences, such as advise on how to get your neighbour’s details (if the neighbouring property is a rental).
The Department of Justice also has information, including what constitutes a dividing fence, providing a Notice to Fence and what to do if you or your neighbour do not agree.