Disclaimer:
You should seek legal or other professional advice before acting or relying on any of the content here or on the internet generally.
Edit: I thought it important to mention there are free legal advice clinics set up in Qld. See link below for locations:
http://communitylegalqld.org.au/
Edit 2: happy for anyone to PM me if they do not wish to air anything out over the internet.
Sounds like you need a plumber, not a lawyer…
Before spending money on a lawyer, try to see where the leak is coming from. You may need a tradesman to determine this. If it is something your insurance covers, then lodge a claim. If its a body corporate issue, let them know and request they pay for replacement of those floorboards.
It could be as easy as a worn out seal that needs replacing.