Firefighters had the blaze knocked down within 20 minutes of responding to the 5:30 a.m. call in the rear of the Blanche Court home off Pershing Street near Madison Avenue.
Damaged areas included the basement, fire floor walls and knee wall beneath the rafters, they said.
Firefighters from Bergenfield, Cresskill, Demarest and New Milford provided mutual aid.
No injuries were reported.
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