Joondalup Detectives First Class Constable Anthony Garcia said the fire started inside the complex on Ammanford Crescent about 4.45am on January 11.
“Department of Fire and Emergency Services (DFES) attended and extinguished the fire on level 1 of the complex,” he said.
“Structural damage occurred to the complex as a result of the fire.”
DFES deemed the fire suspicious.
Anyone with information can report online at crimestoppers wa.com.au or call 1800 333 000, quoting reference 7983.