Adding a Vent/Light

Prevent mildew and moisture from developing in bathrooms with a vent-light combination. Here's need-to-know information and what's involved installing one.

By Gene And Katie Hamilton

Adding a Vent/Light

The sure cure for a damp, dark bathroom is a combination light/vent that senses when it's needed. Bathroom light/vent fans have been around for years, but today you can replace an old one with a "smart" unit that senses when to turn itself on and off. The unit's motion sensor turns the light on or off as people enter and leave. These new "smart" units are a smart addition to anyone's bathroom. Most of the automatic sensing bath light/vent units are available in painted, chrome, brass or wood finishes so you have a choice to match your décor.

The benefits include:
  • An automatic vent that turns on when the humidity level rises and will automatically shut off when the humidity level drops. This will eliminate damp conditions that lead to mildew since you can leave the vent running after a bath or shower and it will make sure all the humid air has been exhausted.
  • Saving in your energy bill because both the light and vent turns itself off. You'll never ask "Who left the bathroom light on?"
What's Involved

It's a straight forward exchange to replace an existing light/vent unit with a new automatic sensing one assuming the bathroom is below an open floor attic so it's possible to see and work between the joists without obstruction.

The job involves removing the old unit and disconnecting wires and adjusting the size of the opening, if necessary, and then reconnecting the new unit to the existing ductwork. Most models are sized to fit between ceiling joists, but some old units are smaller so cutting into the ceiling material is part of the job.

Extenuating circumstances
  • If there's no existing vent/fan and if the bath is below a finished living area instead of an open attic more work is required. That involves making a duct run to an exterior wall, and running new wiring to a junction box and wall switch.
  • If the ceiling joists run perpendicular to the direction of the vent duct, holes cut through joists are needed
  • If the only way to vent the cut is through the roof or through an exterior brick wall
Code requirements

You'll want to hire an electrician for any electrical job such as this so you're confident the wiring is done correctly and meets your local building codes. Since the electrician is already there it's a good time to consider increasing and upgrading or increasing the receptacles to ground-fault circuit devices which are safety features required in all bathrooms.

Related Job Costs: