In the past, we have always responded that this is allowed in NSW but not Queensland and we have been very happy with our answer.
More and more, we are being told that some certifiers are approving duplexes for construction by Owner Builders in Queensland.
We have done considerable research and we confirm that the QBCC still has a restriction under the legislation that prohibits the construction or modification of multiple dwellings, dual occupancies and duplexes under an owner builder permit.
If you are told by your Principal Certifying Authority that it is allowed, then our suggestion to our owner builder students, is to seek clarification from the Queensland Building and Construction Commission (QBCC) for a ruling before you expend any funds on the project.
Failing ti do this may result in the owner builder being in breach of the legislation and be fined or sanctioned as a result.
For those of you who have asked this question, I apologise for the slow reply on this forum, but we wanted to be certain of our facts.
NSW owner builders continue to be able to construct duplexes.
Hope this information is of value.
Best Regards and Happy Owner Building