Seattle police say the fire started around 5 a.m. and since the home already had holes in floors and the roof from the previous fire, quickly spread through the structure and to the roof.
Firefighters were able to get the fire out within 10 minutes and no one was hurt.
The fire last week. described by one neighbor as "a blazing inferno," sent a couple in their 70s to the hospital -- both treated for smoke inhalation while the husband also suffered burns.
Investigators believe the April 29 fire started in the basement or back porch, but they're not yet sure what sparked the blaze and its cause remains undetermined as they have yet to speak with the hospitalized occupants.
Investigators are now tasked with deciphering the evidence from two fires in the same building, and police say the lead investigators from each fire will work closely together to find the cause of both fires.