The incident happened on a plot on Benoni Road, near Patten Road, at about 3.30pm.
A motorist, who did not want to be named, told the City Times she saw a homeless man off Benoni Road drop a lit cigarette, which she said caused the fire.
The fire reportedly spread to three other properties, but the City Times could not confirm whether there were any injuries or damage to property.
Melody Luyt, who lived the house which was consumed in fire, said the unoccupied structure contained antiques which her brother sells.
She and her brother lived in another house behind the one damaged in the fire.
The emotional woman said her relative was too distraught to speak to media.
Luyt said her other brother, Pierre Andre Grobbelaar, was murdered on the same property in 2003.
A firefighter was treated on scene for smoke inhalation.
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