30 years is a significant length of time... Most definitely need to have something formalised IMO.. There would be a legitimate claim on superannuation, and also the land/house kit as it was purchased pre-separation.
The legislation talks about a party that has contributed to the purchase, preservation or conservation of the property as having a financial interest... so the fact that he is also contributing by way of the building also complicates things. Even though the deeds are in your name only, he would have an interest in the place and could have a caveat placed over the title.
In short, this scenario has the potential for significant consequences for you moving into the future if you do not have a formal, legally binding financial agreement or court order... Even if you were to divorce and the 12 month period to file a claim passed, he would only need to show that he had a significant and substantial contribution to the purchase, conservation or preservation of the property and that he would be disadvantaged if leave to file was not granted...
Then there is the super accumulated over 30 years as well. I have little doubt that leave would be granted to file out of time.