For designing houses you usually do not need an architect. All that is strictly required is having an engineer sign off on the structure and council approval. You can design and draft up the whole thing yourself, but don't go there because it is unlikely that your design will be approved without at least some professional input.
In Australia an architect is (legally) someone who is accredited with the Architect’s Registration Board of each state. For residential projects you do not legally require an architect, so many architecture graduates simply do not bother getting official accreditation and use the generic title "Building Designer" instead. There are other building designers who have lesser qualifications, and they may well be just as good at designing houses (e.g. experienced draftsman), but there are also some designers who really do not know what they are doing.