square bath fa in ceiling

Kendall "aka Renos"

Founder, Lead Instructor of Renos 4 Pros and Joes and Bathroom Update Guide

Read This Before Selecting a Bath Fan Installer

Whether you’re adding a new bathroom, or remodeling or updating an existing one, a bathroom exhaust fan is an important and often necessary feature. It’s easy to get totally absorbed with shopping for tile, bathtubs, and plumbing fixtures and end up leaving the bathroom exhaust fan as an afterthought. Regardless of the path you take to reach this point, you will eventually have to determine: “Who installs bathroom exhaust fans?”

In short, bathroom exhaust fans are installed by general contractors, electricians, heating and air conditioning contractors and handymen. The installation process can range from relatively straightforward to quite complex. The size and scope of your project can help you determine what type of contractor is the best fit for the job. If you are doing a complete remodel or new construction and you’ve hired a contractor to handle the entire project he/she will usually handle the bathroom exhaust fan installation. If the fan installation or replacement is an a la carte task and is not part of a larger project then the best person for the job could vary. Below we will discuss several installation scenarios, the scope of work, and some insight on who may be your best choice.


Replacing the bath exhaust fan can be straightforward if it’s being installed in a bathroom that already has a bathroom fan, especially if you are replacing the existing fan with the exact same style fan.

Regardless of who does the bathroom fan installation bathroom, one of the most important things that you can do is confirm that the existing bathroom fan is correctly installed. This falls under the category of due diligence and is worth doing on most remodel or retrofit installs.

How does a bath fan work?

A bathroom fan is powered by electricity which is supplied by an electrical wire. The electrical wire that supplies power to the bathroom fan is usually in the attic or above the ceiling. Attics are commonplace to find hidden building issues. The main reason is that attics are usually difficult to access. Attics are often:

  • Hot
  • Stuffy
  • Filled with scratchy insulation and cobwebs
  • Require you to crawl on your stomach and knees, and
  • if no subfloor is installed, you will have to walk on the ceiling joists 
  • There is always a risk of accidentally stepping through the ceiling.


For these reasons, no one likes to go up into attics and check the work after it’s done. When I say no one, that includes homeowners, contractors, building inspectors, and home inspectors and anyone else. All these factors contribute to a higher likelihood that you could possibly find issues.


Where do bathroom exhaust fans vent?

Bathroom exhaust fans should always vent to the exterior. Out through a roof or a gable are the most preferred locations. Venting out through a soffit is an option, but its not the most desirable location because the humid air can rise and linger under the soffit. However, in instances where venting options are limited, the soffit location may be the best option for your vent.

One of the most common problems that you find with bath exhaust fans is that they are not vented to the exterior of the property. This issue is very common in older homes. It was standard practice in many areas to vent the fan directly into the attic.

This type of scenario can be problematic because it allows the fan to blow the moist humid air directly up into the attic area which exposes the home’s structural framing to moisture. I have seen quite a few in my time that didn’t even have a vent pipe attached to the fan.

Know This About Bathroom Exhaust Fan Wiring

Another common problem found in attics is electrical wiring issues. Its common to find two wires spliced together. These spliced locations are required to be properly secured with wire nuts and electrical tape. The wires that you find laying in an attic may or may not meet these requirements.

Additionally, these spliced wires are also required to be secured inside what’s called a junction box. A junction box creates a 5-sided barrier around the wires connections where the bare wires have been exposed. Most junction boxes used today are blue in color.

The junction box is also required to have a cover on it. This helps prevent anything from coming into contact and resting on top of or close to the spliced wires. Junction boxes and covers are typically sold separately but are both usually sold side by side at most home improvement retailers.

Replacing with the Exact Same Bath Fan

If you are replacing an existing attic fan with the exact same style then your installation could be fairly straightforward. Most bathrooms have an entry-level bathroom fan. The bath fan is typically square in shape and the design has remained the same for many years. You can pick one up at your local big box retailer and it’s a relatively straightforward install.


Installing a Bath Fan as Part of a Full Bathroom Project

If you’re working on a larger project where you have multiple contractors it’s important to get a clear understanding of who is providing each service. For example, on my large projects, where I have all the major trades present; the electrician and the heating and air contractor both have separate responsibilities with regard to the installation of the bathroom fan.

A full bathroom remodel where all the building components are removed and replaced is very similar to new construction because all of the framing is exposed. On this type of project, the heating and air contractor is responsible for installing the exhaust fan duct. This means that he also cuts the whole at the exterior location and installs the vent there and he connects the duct and leaves it hanging from the ceiling in the bathroom.

The electrician is responsible for running the wire that will supply the bathroom fan as well as the actual installation of the bathroom fan and connecting the vent. These steps occur during the rough-in stages of electrical & HVAC work.

When its time for electrical and HV AC final inspections the switches and switch plate covers have to be installed for the bath fan as well as the ceiling vent fan cover. The cover is the white plastic Grill that you typically see and the ceiling of bathrooms that have exhaust fans.

Before You Try to Install the Fan Yourself Know This

The basic exhaust fan, which is what’s most commonly found in most bathrooms has three parts: The rough fan housing, the fan itself, and the fan vent cover. The fan housing is installed by hardwiring it to the wire that is supplying it power. In other words, it does not have a plug.

The actual fan fit inside of the housing. There are slots on each side of the housing and the fan pops in. The fan has a very short cord with a two-prong plug that connects to the outlet on the fan housing. Finally, you install the vent cover.

If you are installing a bathroom exhaust fan in a location where there was not one previously, you will need to run the ventilation duct to the exterior. In order to this, you will probably have to go through the roof, a wall, or the soffit. This is an important step of the installation process because this new opening must be properly sealed to prevent water, insects, and other pests.


Installing a Bath Fan, But Arent Doing a Remodel?  Consider This.

The most difficult bath fan installation scenario is the ala carte install. For this project scenario, the whole scope of work is to install the fan, and it is not part of a larger project. The project is more challenging because the installer has to work with what’s there. He may have to install electrical wiring, move insulation, cut through the finished ceiling in the appropriate size, in addition to cutting through the wall or ceiling to vent to the outside.

And perhaps the most challenging part of all is working in the attic on your stomach or back while trying not to step or fall through the ceiling and into the room below. In comparison, a new construction bathroom or gut remodel allows the contractors to work from a step ladder on an open ceiling. This makes the work far less strenuous.

Make Sure You Do This Before the Contractor Starts the Job

Because you have the potential to need so many different skills to complete this install, you should consider hiring a general contractor. You also may be able to find a handyman that can complete the job. In some cases, you may also find an electrician or an HVAC contractor that can also do the install.

It really boils down to the training and skill level of the people or person performing the job. There is the functional component of the project which is installing and venting the fan and making it work. But there is also the detail work which includes making sure that the holes that are cut for the vents through walls and ceilings are properly sized and sealed and that the vent covers don’t leave any unsightly gaps between the fan housing and the drywall or plaster ceiling.

Also, be aware that there situations where the ceiling will have to be repaired and painted as part of the bath fan install. You will need to have clear communication with the contractors.  Ask enough questions to ensure that the contractor is willing and able to handle all potential foreseen aspects of the job. Reaching a clear understanding with the contractor upfront will help ensure that they are able to create an end result that meets your expectations.