How To Install A Bathroom Fan Where One Does Not Exist

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If you have a bathroom that does not have a fan, you probably use strategies such as leaving the door or window open to let the odor and steam out.

While this may be a short-term solution, you probably suffer because the odor and steam fill up your bedroom or living room for the next several minutes. 

What Happens if your Bathroom does not have an Exhaust Fan?

Additionally, when washroom moisture is trapped and cannot escape, it causes stale odors to collect. Damp air is likely to harm your fabrics, including towels and curtains, wallboards, bathroom paint, windows and doors, and fixtures and cabinets. 

Rising humidity levels may also cause the breeding of microorganisms such as mold and mildew. All these can affect your health negatively. Considering all the damage that moisture can cause, you must control it. 

The solution to all these problems is to install a bathroom exhaust fan. It will improve the indoor air quality of your entire house by removing the humid air using a vent that connects your bathroom to the exterior of your house. 

You can choose to do the exhaust fan installation yourself or hire a professional. If you plan to do this yourself, you need to learn how you can install the bathroom exhaust fan by yourself successfully. 

In this article, you will learn about the disadvantages of not having suitable ventilation, factors you need to consider before buying a new bathroom fan, how to work through the installation process, and what aspects of the building code you need to be aware of before you install a new bathroom exhaust fan.

All you Need to Know Before the Installation 

Bathroom fans come in a variety of sizes and offer various features. You must explore your options and read up on the essential qualities of a bathroom fan that will make it a good fit for your bathroom. 

What is CFM Rating?

Before you install your bathroom exhaust fan, you need to be aware of the right size of the fan that will be a good fit for your bathroom. To do this, you need the CFM rate. The CFM or cubic feet per minute will help you determine the appropriate strength of the exhaust fan that your bathroom needs.

CFM is the amount of damp air that the exhaust fan vent will remove per minute. If you have a small-sized bathroom, you will need an exhaust fan with a lower CFM, whereas you will need a higher CFM for a large-sized bathroom. 

To calculate the CFM, first, measure the square feet of your bathroom area and then multiply it by 1.1. For example, if the size of your bathroom is 100 square feet, you will need a bathroom exhaust fan with a 110 CFM rating. 

When you go out to purchase your new bathroom exhaust fan, look for the CFM rating first. It will be printed on the box. 

What is Sound Rating?

The next important element you need to check before buying your bathroom exhaust fan is the sound rating. It is measured in sones and is also printed outside the box. Good quality fans are engineered to run more quietly than low-priced, poor-quality products.  

Bathroom exhaust fans usually have a sound rating in the range of 0.5 to 6.0 sones, where 0.5 is very quiet, and 6.0 means it is very loud. Look for a bathroom exhaust fan with a sone rating of approximately 1 instead of 3 or 4. 

Consider Special Features

Bathroom fans also come with additional features that can add to the appearance of your bathroom. A bathroom fan with light will add more brightness to your bathroom, and you can avoid having to add a separate fixture. 

You can also choose a fan with variable speed control that will allow you to get additional power when generating more humidity, such as with a jetted tub or while taking a long shower. 

Bathroom fans also come with a humidistat, a feature that enables the fan to operate when required. With this feature, the fan will turn on automatically at a certain level of humidity. This will help you save on electricity as the bathroom exhaust fan will only function only when the humidity level in the room exceeds a specified level.

Apart from giving you convenience, this bathroom fan is also a good option wherever you are uncertain about how the users will use it. This could be in a rental apartment or with young children. 

These are some of the unique features that can help you cope with various ventilation situations.

Use PVC or Metal for Ductwork

It is always advisable to avoid the cheaper flexible duct of flex duct for your bathroom fan vent. In addition to impeding the airflow, it can tear or crush easily. Using PVC plastic or rigid metal to fabricate your bathroom fan duct, you can ensure that your fan will perform well in the long term.  

Always keep your duct runs straight and short to whatever extent possible for better performance. This rule applies to all types of ductwork. When a duct run is longer or more convoluted, the fan ends up working much harder to do its work. If this is unavoidable, and you have to use elbows for several direction changes, or a very long run, then it is important to upsize the bathroom fan.    

What Tools do you Need?

You only need basic carpentry and electrical skills for the DIY installation of your bathroom exhaust fan. However, before you start working on the installation, here is a list of all the tools and materials you are likely to need. Make sure that you have them at hand.

  • Pencil
  • Jigsaw
  • Power drill
  • Screwdriver
  • Wire nuts
  • Flexible duct pipe (approximately 6 feet)
  • Vent cap
  • Screws
  • Roofing nails
  • Cement & shingles
  • Roof brackets 
  • Silicone caulk
  • Cordless drill
  • Safety glasses
  • Safety harness
  • Stepladder
  • Mask for blocking dust 

Because this is a new installation, you won’t have any ducting in the bathroom. You will route the new duct to the outside of your house by accessing the attic space right above the bathroom ceiling. 

Building Code

Before you move ahead to the installation process, it is important to understand some elementary code requirements and basic history. 

When we did not have indoor plumbing, people understood the need for outhouses and their ventilation. With bathrooms moving indoors, it was even more important to remove excess moisture and odors. Hence the presence of a building code to ensure the health and safety of people. 

The current building code now applicable to most municipalities requires bathrooms to have ventilation through an operable window or bathroom exhaust fan. Ventilation through a window is a minimum standard and cannot be considered to be reliable or effective. 

Expecting people to open the bathroom window to get rid of excess moisture is not reliable, particularly in cold weather. A bathroom exhaust fan with a vent is the best and most effective way of getting moisture out of your bathroom. 

You must check the building code applicable to your locality so you can ensure that your bathroom fan and its installation process meet the requirements of the code. 

How To Install A Bathroom Fan Where One Does Not Exist

Step 1 – Find your power source

You need to check your electrical code. Based on that, choose between running a complete circuit for the bathroom fan or sharing it with the lighting circuit of the bathroom. 

If you can do the electrical work, proceed with establishing a new circuit by running a cable from the ceiling area to the service panel. You can also get help from a professional to complete this job. 

Step 2 – Identify vent point

To locate an appropriate point for the vent, you need to keep a few things in mind. You have to run a duct route directly from the fan to the outside of your house. There can be a distance of 6 feet or less between the vent and the point of exit. 

It is important that there are no sharp bends because they can obstruct the airflow. The bathroom fan vent should be located close to the area that produces the maximum moisture, probably near the shower or tub.  

Ideally, the duct should run to the sidewall so that you can avoid the possibility of roof leakage in the future. Once you have identified the location of the right point, drill a hole in the middle. 

Step 3 – Cut exterior opening

Take the vent cap, silicone caulk, pencil, reciprocating saw, and cordless drill and saw to access the sidewall. Then position the vent cap on the locator hole and draw around the mark using your pencil at the location where the circular vent will fit. 

Use the locator hole as your starting point and use the saw to cut the hole. By applying the silicone caulk and screws, attach the vent cap. 

Step 4 – Cut interior opening

Next, you need to locate the joists in the bathroom. Mark the lines you will cut using the metal fan housing parallel or a paper template. Cut across the drywall using the jab saw. 

Step 5 – Fit vent fan to joist

You will need a partner to perform the next step. Take the screws, bathroom fan housing, drill, and a light and access your attic. Place the fan in the cut-out hole and use your cordless drill for screwing it into the side of the joist.

Alternatively, you can suspend the fan so that it is not next to the joist. You can also use suspension brackets, as most vent fans have suspension brackets. Next, pass the wire using the fan housing side, ensuring that there is a least 7 inches of the wire extending into the housing. 

Step 6 – Run tubing from fan to outside

In the bathroom, make sure that the fan is placed vertically. Next, you will place the flexible tube and attach it to the vent and fan in the attic. Again, it would help if you avoided bends to whatever extent possible. 

Step 7 – Attach fan unit to the housing

Review the instructions from the manufacturer to complete attaching the fan unit to the housing in the bathroom. Then, use the striped side of the wires to hardwire them into the fan. You can do it by yourself or contact an electrician if you are not confident about doing this. 

Attach the cover once you are done. Then, all you have to do is attach the decorative plastic grill to the bathroom fan and turn the circuit breaker on. 

Congratulations! You have completed the installation process. That is it! Now go back to your bathroom and turn on the switch so that you can test your bathroom fan installation.

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