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Bathroom Exhaust Fan Cost Guide

Considering the amount of moisture that is generated in bathrooms, it's no surprise that they tend to attract a lot of mold and mildew. This is why a quality exhaust fan can come in handy. Bathroom exhaust fans help circulate and remove the hot air that's generated during daily baths and showers. This moisture-rich air can lead to bad odor, mildew and damage to a bathroom. Consider the following information before purchasing and installing a bathroom exhaust fan.

The Costs

  • Minimum cost of bathroom exhaust fan: $15
  • Maximum cost of bathroom exhaust fan: $550

Motor Sone and CFM Ratings

A sone is a measurement of the noise associated with motor operation of a bathroom exhaust fan. The bathroom sone ranges from 1 to 4. A quiet fan is considered sone 2 or less. Higher performance fans may be difficult to obtain below sone 2 for larger bathrooms. A sone 3 is still considered moderately low in noise. The sound is reduced by a combination of a damper and a brushless motor that is mounted to reduce sound vibration. Larger motors are more difficult to rate at a low sone.

The CFM rating is distinctly different from sone. CFM is the rating at which moisture is removed from the bathroom. A bathroom fan should be able to remove 1 CFM for each square feet of space. You can calculate this space by multiplying the length, width, and height of the bathroom by 0.13 to find the best sone rating for your bathroom. Homes that are older or more airtight may benefit from a fan with a CFM rating higher than the requirement of the bathroom to remove moisture as quickly as possible. Ratings for most bath fans range from 50 all the way up to 300 for large bathrooms. There are industrial level fans rated up to 1,000 CFM as well.


There are two types of timers for bathroom exhaust fans: preset and programmable. Both timer switches use a relay to start the bathroom fan to exhaust. A preset switch will have designated times at which the bathroom fan will operate after usage. A programmable switch may operate independently during the day and is often used in highly humid environments where closed spaces need to be "aired out" to remove moisture and create a positive airflow for house ventilation.

Programmable switches can also be a manual dial component for single use in the bathroom. The dial can be preset and adjusted from season to season as humidity changes.

In-line Exhaust Fans

Remote in-line fans are space-saving exhaust fans that can be placed in more ubiquitous areas such as a spot under a door or shelf. The housing is considered more discrete than a flushmount style exhaust fan. The ductwork is usually smaller in size and part of a high velocity motor unit, much like a high velocity air exchange unit but in a smaller package.

Ceiling or flush mount exhaust fans

A flushmount ceiling model is the most common type of bathroom fan. Many models will replace considerably older models with the addition of a conversion kit. This reduces the need to go in an attic and install an entirely new bay. The new motor unit just goes in place of the old unit.

Heat Lamps

Heat lamps are often included as part of a combination exhaust fan unit. The concept is a high intensity bulb or combination light unit that can warm a cold and drafty bathroom quickly. Most bulbs are infrared bulb heaters that use convection heat downward in the bathroom.

Advantages & Disadvantages

An exhaust fan is often a requirement in a bathroom to prevent mold and mildew. It is usually a fast install for most homes. It is also relatively DIY-friendly in most cases. Bathroom exhaust fans come in a variety of styles and functions for any bathroom on the market. Exhaust fans will require additional cleaning to prevent dust from entering the motor. There are units with graduated fins that reduce the amount of dust that will draw up into the motor unit. Each one will have a distinct advantage and drawback depending on the application.

Combination Units

Combination units often bring the best of all worlds to a bathroom. They can heat as well as provide a nightlight to avoid stumbling in the dark to reach for a light switch. They are usually not much more in price than traditional stand-alone models. A drawback to these units is the additional electrical work requirements. There will need to be adequate room in the circuit breaker for additional wiring. Most units with a heat lamp need to be dedicated and cannot cross over from wiring in the bathroom that may be used with lighting. This usually involves additional labor cost and reconfiguring additional house wiring.

High CFM units

Units that are have a high rating for removing moisture can dramatically reduce the musty odor of a bathroom and prevent mildew from forming on shower walls or even the bathroom wall itself. One drawback of these units is that they usually have a substantially bigger housing than the previous unit. Certain brands may require an expansion of the ceiling bay that held the older unit and new ductwork up through the attic. They also may be somewhat louder than the older unit, which is something to consider if the desire is quiet operation.

Homeowners will need to evaluate if they want to replace the old flush mount unit or install an in-line unit. An in-line unit will be more discreet and may flush moisture out more quickly, but require some more extensive ducting behind the walls up to a vent. Flush mount units have standard mounting instructions and are DIY-friendly, but may be more trial and error in terms of the humidity environment naturally found in the bathroom. Using a small hygrometer will help determine the moisture before and after to determine fan requirements.

Last updated on May 6, 2016

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