The fire started just before 9 p.m. at Tommy's Pallets, off Route 206 in Columbus.
Video from Chopper 6 captured the massive flames engulfing the building on Monday night.
Chopper 6 over massive fire at pallet supply company in NJ
It struck four alarms before crews got the fire contained around 2:45 a.m. on Tuesday.
Firefighters continued separating the rubble and debris, which is expected to burn itself out.
No injuries were reported.
Investigators are expected to return in the daylight hours to work out what sparked the blaze.