The blaze started just before 7 p.m. Monday along the 2000 block of East Boston Street. The flames were not extinguished until around 1:00 a.m. Tuesday.
The vacant building, measuring about 100 feet by 100 feet, had heavy flames upon the arrival of first responders.
Firefighters sounded a second alarm, and then a third at 7:02 p.m. The fire reached a 5th alarm shortly after 9 p.m.
Nearby homes were evacuated and a shelter was set up at the Kensington High School by the American Red Cross.
The cause of the fire is under investigation. No injuries have been reported.
Tom Callahan, of Local Firefighters 22, blamed Philadelphia's brownout policy as part of the reason the fire Monday night became so intense.
"They were back filling in the firehouses," said Callahan. "Engine 45, which is at 26th and York, was brown out tonight. This could have made a difference."
The building used to house a company warehouse, Cavco, which made vinyl replacement windows.