How To Install A Bathroom Fan Roof Vent? Explained By An Expert

How To Install A Bathroom Fan Roof Vent

A bathroom ventilating fan is an important element of the space that eliminates or reduces the possibilities of stale odors, foggy windows, and steamy mirrors. Besides, it also helps prevent moisture-related issues like the growth of mildew and mold.

It’s important to ensure the perfect installation of the ventilating fan and to make the system work efficiently for the bathroom space,

If you want to know How to install a roof vent for a bathroom fan, this article will be your perfect guide. It covers every aspect of the Bathroom ventilating fan installation process. Read on. 

Important Highlights Relating To Installation Of Bathroom Fan Roof Vent

Skill:3 out of 5 Moderate Climbing onto a roof is required, although the work itself is relatively easy.
Cost:Depending on the size and design of the vent hood, it might cost$30 to $60, on average.
Estimated Time:Approximately 2 to 4 hours

Tools And Material Require For Bathroom Fan Roof Vent Installation 

Drill & BitsBathroom Exhaust Fan
Oscillating Saw With Metal Cutting BladeWire Connectors
Hole SawHVAC Tape
Circuit TesterDrywall
Putty KnifeDuct Clamps
Drop ClothsFlexible Insulated Duct
Ladder or Step StoolLumber (1x or 2x)
ScrewdriversRoof Vent Cap
Eye ProtectionRoofing Cement
Work GlovesRoofing Nails
Hearing Protection   Screws
Tape MeasureSpackling Compound Patch Kit
Utility Knife
Wire Strippers
Straight Edge

Steps To Installation A Bathroom Fan Roof Vent

Step 1: Determine Route Of The Ventilation

It is the first and the most important step to bathroom roof vent installation. It requires proper ventilation, preferably outdoors. You can choose the route through the attic.

Alternatively, you may consider venting the route through your house’s sidewalls. Generally, vents and ducts for such purposes are installed during the construction of a house. If there is no duct, you may take the help of a professional. 

 If the attic of your home is accessible, you may consider venting the fan either through the roof or a gable wall. However, it’s recommended to avoid venting the fan through a ridge vent or soffit vent. 

Note: Make sure the bathroom vent fan exhausts to the house outdoors. The duct shouldn’t blow into an enclosed area like an attic or a crawlspace.

Also, bathroom exhaust fan installation will be comparatively quicker if you take the help of a friend or your spouse. It’s best to hire a professional for the job as they have the relevant experience and expertise needed to get the best job done perfectly without the risk of any damage. 

Step 2: Take Note Of The Available Electrical Options And The Fan Size. 

If you already have a switch for the bathroom ventilation fan, then you may proceed with using it for the new installation. Note that some fans come with a light, and the best part is that you can connect them to an additional switch. They can be operated separately. You may get new wiring for a new or double switch if need be.

Simply learning to install a bathroom fan vent through the roof isn’t sufficient. You need to also take care of other factors such as calculating cubic feet per minute and the fan size.

The recommended calculation should be according to the 10 cfm rate per 100 sq ft of floor space. If the bathroom size is 300 square feet, the ventilation rate would be 3,000 cfm.

Step 3: Find The Appropriate Location On The Roof For The Bathroom Fan.

The next step is to find a perfect spot on your bathroom’s roof for the roof vent. The vent should be close to the roof fan. It’ll reduce the count of bends and duct length.

However, there should be two feet (minimum) distance between the fan roof vent and other roof vents (for chimneys, roof valleys, etc.).  

Once you are done choosing the location for the vent, hammer a nail through the truss bay or rafter from your attic. The professionals use this trick to locate the exact position of the roof vent.

Step 4: Prepare The Top Shingles For The Roof Fan Vent Body. 

Can you vent a bathroom fan through a roof vent? Here are all your answers. 

Cut a hole inside the bathroom ceiling. It’s suggested to make the hole towards the exact area of the bathroom. Start by measuring the fan’s perimeter and then draw a rectangle or square on that spot.

After the area is marked, start with the cutting process using a jigsaw. Make sure to follow the line drawn previously for a precise cut. Once you are done cutting the marked area, remove the waste materials from that area with the help of a chisel and hammer.

The hole should be clean and made through your home’s attic. Next, insert the fan housing box inside that hole to confirm whether the cut is perfect according to the fan size.

Step 5: Fit The Hood Of The Roof Vent. 

After cutting out the first layer of the shingle layer, dry-fit the fan’s roof vent. For a perfect fit, remove the seal that surrounds the shingles with the help of a pry bar. The purpose is to make the metal flange go underneath the shingles’ top layer. Make sure the top and side parts of the metal flange are fitted perfectly with its bottom portion above the shingles.

Step 6: Make The Roof Vent Hole

It is one of the crucial steps of the installation process. Make the roof vent hole for the bathroom exhaust fan. You can easily determine the hole area by following the marking of the hammered nail in Step-3.

Use an extension ladder to reach on top of the bathroom roof. Check the area where the nail was hammered and make a round hole of approximately 4 inches because the width of the duct line is also 4-inches. A hole smaller or bigger than this may create issues.

You may need to remove the roof sheets of the surrounding area to make the hole. If the roof includes a covering of shingles, you can remove them with the help of a utility knife.

Try up the roof’s seal that covers the sheets using a flat pry bar. Use a round-shaped hole of approximately 4 inches to remove the wood from the roof. Use a blade saw for the task if it’s a concrete roof.

Step 7: Duct Collar Or Connector Installation 

A duct collar or connector is a tiny section included in the metal piping for connecting the roof vent’s duct hose.

Generally, one section of the duct collar is crimped, allowing the duct hose to slide into the duct collar. After sealing the duct hose, add a zip tie or foil tape to the setting to fit the duct connector.

Alternatively, the connector can also be fitted into the bathroom’s roof hole. 

Step 8: Caulking And Nailing The Roof Vent

After the collar is secured and dry-fitted to the roof, the next step is the installation of the roof vent over the connector and towards the side or upper part of the flanges. But inserting the roof vent, make sure to caulk on the vent flange’s underside. Put caulking only on the side and upper part of the flanges. Avoid caulking the bottom part. 

Don’t caulk the bottom flange so that water or condensation can drip out easily. Once the roof vent cap is inserted, hammer the roofing nails into the roof vent’s flange and the roof sheathing. 

Step 9: Caulking The Edges Of The Top And Bottom Shingles 

After nailing the roof vent, caulk the edges of the shingles, which are on the side and upper flanges.

Concluding Word 

Hope this article solves your major doubts and queries. Investing in the best model for a bathroom exhaust fan doesn’t mean it will sort the purpose to its optimal capacity and give you the best value for money. You need to ensure it’s properly installed to reap its benefits to the best possible extent. It needs a good understanding of installing a bathroom roof fan with precision. Follow the above-listed steps carefully to get the job done efficiently.

Related Questions And Answers

Is It Better To Vent The Bathroom Fan Through The Roof Or Soffit?

The bathroom fan exhaust should be vented through the roof directly to the home’s exterior part. Avoid adding the vent termination in the soffit or overhang of the roof. Also, avoid putting it under the overhang or near a wall. 

Is It Ok To Vent A Bathroom Exhaust Fan Into The Attic?

It isn’t a good idea to dump the hot and moist air into the attic through the exhaust fan. A bathroom exhaust vent aims to remove moist, hot air from the space. And the air that’s removed by the fan may easily get sucked up into the soffit vents and drawn into the attic.

Does A Bathroom Exhaust Fan Need To Be On A GFCI?

The National Electrical Code hasn’t specified any GFCI protection requirement for an exhaust fan. However, the requirement is mentioned in the exhaust fan installation instruction with the product. 

Does A Bathroom Exhaust Fan Need Its Circuit?

Bathroom vent fans with an in-built heater should have a circuit of approximately 20-amp. It’s termed a “dedicated” circuit as it serves a single fixture or appliance. 

Can A Bathroom Fan And Light Be On The Same Switch?

Yes, the bathroom light and fan can be on the same switch. Most of the bathroom fans have lights attached to them. Both can either be wired to a single switch on one circuit or wired separately to different circuits and switches.

How Many Bathroom Fans Can You Have On One Circuit?

Experts recommend having one fan on one circuit. While having two fans on one vent isn’t permitted, you can consider making one vent and one fan serving two bathrooms.

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