Flames ripped through a house on Corfield Street, in Gosnells, on Monday afternoon, causing an estimated $400,000 in damages.
Department of Fire and Emergency Services crews responded to a triple-zero call around 2.25pm on February 15.
Witnesses reported seeing smoke billow from the property.
Firefighters from Maddington, Murdoch, and Welshpool attended the scene, and prevented the fire from spreading to other homes.
The blaze was brought under control at approximately 3.05pm, before being fully extinguished around 3.50pm.
Following an investigation, DFES deemed the cause to be accidental.