A ceiling fan box is a junction box that supports ceiling fans and other light fixtures. It can be screwed directly to a ceiling joist for new construction, or mounted to a hanger installed between joists in existing finished ceilings. The box also has a special bar to support the weight of a ceiling fan, and is marked “for use with ceiling fans.”
In summer, fans cool the room by drawing off heat from the ceiling, saving energy that’s typically wasted in air conditioning. They also help circulate warm air in winter, keeping the space cozy without increasing heating costs. Before mounting a ceiling fan, turn off the electricity to the circuit and remove the old fixture. Then inspect the existing box: If it’s nailed to the joist, pry it loose with a flat pry bar and remove the nails. If the box is too shallow to hold a fan, choose a pan or saddle box that gets screwed straight onto a joist.
For new construction, install a ceiling fan-rated box before putting up drywall. It’s easier to do than installing a box for a regular light fixture. These boxes have a built-in bar to support the weight of a fan, and are available in several shapes, including an octagon for angled ceilings and a pancake box for sloped ceilings. There are also versions with knockout holes to accommodate electrical wires and a nonmetallic cable clamp for protecting the wiring.