The fire broke out on the second floor of the Hillside Avenue home around 5:15 a.m. and blew through the attic.
A candle left burning overnight may have been to blame, responders said.
Firefighters had the bulk of the blaze knocked down within 20 minutes.
A quick response prevented even more extensive damage.
No injuries were reported.
Among those assisting Westwood firefighters were their colleagues from Hillsdale and Woodcliff Lake, with an ambulance from Old Tappan on standby.
Click here to follow Daily Voice Pascack Valley and receive free news updates.