Creator Syndicate

Dear James: I want to add a bathroom vent fan with an overhead light. The window does not provide enough light. What are some tips for installing one and venting it up through the the roof? — Kathy T.

Dear Kathy: Although having a window in a bathroom with its natural light is great for putting on makeup, it is not always the best ventilation for a bathroom. Excess moisture in the air from showering or bathing can damage paint, warp doors and cause mold growth.

Having a light overhead is also a plus, even with adequate natural light from one side by the window. Having light come from many directions is best.

Your first step is to select a bathroom vent fan/light. You will be amazed at the many design and styling options available. The most important selection criteria are the size of the vent fan and the type of light.

As a rule of thumb, a 5×6 bathroom would require a 33 cubic feet per minute of air flow fan. A 8×10 bathroom would require a 88 cfm fan.

Your three choices of lights are typically incandescent bulbs, fluorescent tubes or LEDs. Incandescent bulbs, particularly halogen bulbs, provide good color rendition so your makeup still looks the same after you leave the bathroom.

Fluorescent tubes use about 75 percent less electricity and last about ten times longer. This is an advantage if it difficult to reach the fan to replace bulbs. LED’s are the most efficient and last the longest. Daylight ones provide a whiter light to simulate natural light.

Although installing the vent fan should not take long, start the job in the morning in case you run into problems. You will have to remove the old light fixture, so you will have to rely on the natural light from the window or bring in some additional lamps.

Before starting this project, switch off the electric power at the circuit breaker panel. Test the existing light to make sure you switched off the correct breaker. Also tell your other family members you switched off the breaker or put a note on it.

If another family member notices a light or clock is off in another room, they may check the breaker box and switch the power back on without knowing you are working on the wiring.

If you want to operate the fan and the light independently, you may have to run another cable with an extra wire to the fan/light unit and replace the existing single switch with a double one.

Remove your existing ceiling light and install the fan housing in the same location. The conduit box for the old light should be located at a joist, so secure the fan housing there. Make sure to secure it solidly to minimize vibration and noise.

The simplest method to install the fan vent duct is to connect it to a vent in the soffit under the roof overhang. Don’t just run the duct up into the attic because the excess moisture in your attic can cause problems. If you have a pretty straight shot to the soffit with only one or two bends, use round aluminum duct. If there will be several twists and turns, flexible dryer duct is a better option.

Send your questions to Here’s How, 6906 Royalgreen Dr., Cincinnati, OH 45244 or visit