Is it permitted?
Some schemes allow a second dwelling outright, others require consent, and some limit size. Title conditions may restrict the property to a single dwelling.
Building lines and coverage
A second dwelling must still comply with building lines, coverage and height, or obtain relaxations.
Separate title is a different process
If you want to sell the second dwelling separately, a subdivision or sectional title process is needed.
General information only, not legal advice. Requirements differ between municipalities.