Welding work in the master bathroom of the Sunset Avenue residence ignited the three-alarm blaze, which spread to the attic, around 10:40 p.m., responders said.
Firefighters had it knocked down and under control in a little over a half hour.
No injuries were reported, officials said.
Mutual aid responders either at the scene or in coverage included firefighters from Closter, Demarest, Dumont, Hackensack, Harrington Park, New Milford and Tenafly. Haworth police and EMS also responded.
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