Install Bathroom Fan

Install Bathroom Fan

Install the new fan. Head back down to your bathroom and remove the new fan from its packaging. If it has the same measurements as your old fan, you will be able to install it immediately. But if the new fan is bigger than the old one, you will need to enlarge the hole in your ceiling. You can do this by tracing the outline of your new fan onto the ceiling, then cutting around the outline with a drywall saw. If your new fan is smaller than the old one, you can caulk around the edges of the housing unit to fill in any gaps once the fan is installed. Go to the attic and lower the new fan into the preexisting or newly enlarged hole. Make sure the unit is properly oriented for all electrical and duct work connections. Slide out the extendable mounting brackets and secure them to the joists using your power drill and 1 inch (2.5 cm) drywall screws. You may need a helper to hold the fan in place from below as you do this.
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Install Bathroom Fan

Step One // How to Install a Bathroom Vent Fan Bath Vent Overview Photo by Keller & Keller Photography A bathroom without a ventilation fan is like a fireplace without a chimney: If you fail to pull the moisture generated in the bathroom out of there, it will migrate into the walls and grow mold and mildew, or blister paint and peel wallpaper. One reason many households still don’t have bath fans is that they can be intimidating to install. That’s why we asked This Old House general contractor Tom Silva to show us how. The bathroom here is below an accessible attic, so Tom ran the exhaust duct across the attic and out a gable end. Bath vent fans are rated by how many cubic feet of air they can move in one minute, known as the CFM rating. To determine which size fan to buy for your bath, multiply the room’s square footage by 1.1. For example, a 100-square-foot bath would require a 110 CFM-rated fan. Fan’ also have a sound rating, measured in sones. (A modern refrigerator operates at about one sone.) Vent fans range from as low as 0.5 sone up to about 6.0 sones. You’ll find both the CFM and sone ratings printed on the vent fan’s box.
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Install Bathroom Fan

Choose the location of the fan. The location of your bathroom fan is important. It should be installed at the center point between your shower and toilet for optimum ventilation. However, if your bathroom is very large, you may need to install more than one fan. If you are installing a new fan, you will need to consider the layout of your attic, where the bulk of the fan will be located. It should be placed in the the space between two joists, in an area free from any pipes or other obstructions. If you are replacing an old fan, the easiest thing to do is just to put the new fan in same location (unless you have a very good reason for wanting it in a different spot).
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Install Bathroom Fan

Step Two // How to Install a Bathroom Vent Fan Drill a Reference Hole Photo by Keller & Keller Photography Draw a mark on the bathroom ceiling where you’d like to install the vent fan. For optimum performance, locate it between the shower and the toilet. Use an extra-long, 3/8-inch-diameter spade bit to bore a reference hole through the ceiling and into the attic. Climb into the attic and clear away any insulation from around the hole. Now use the reference hole to determine the exact position of the fan. Measure the vent fan housing. Try to position the vent fan directly between two joists near your reference hole. Take into account any nearby pipes or other obstructions. Note the final position of the vent fan in relation to the reference hole.  
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Install Bathroom Fan

A bathroom without a ventilation fan is like a fireplace without a chimney: If you fail to pull the moisture generated in the bathroom out of there, it will migrate into the walls and grow mold and mildew, or blister paint and peel wallpaper. One reason many households still don’t have bath fans is that they can be intimidating to install. That’s why we asked This Old House general contractor Tom Silva to show us how. The bathroom here is below an accessible attic, so Tom ran the exhaust duct across the attic and out a gable end. Bath vent fans are rated by how many cubic feet of air they can move in one minute, known as the CFM rating. To determine which size fan to buy for your bath, multiply the room’s square footage by 1.1. For example, a 100-square-foot bath would require a 110 CFM-rated fan. Fan’ also have a sound rating, measured in sones. (A modern refrigerator operates at about one sone.) Vent fans range from as low as 0.5 sone up to about 6.0 sones. You’ll find both the CFM and sone ratings printed on the vent fan’s box.
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Install Bathroom Fan

Step Five // How to Install a Bathroom Vent Fan Position the Fan Photo by Keller & Keller Photography Back in the attic, attach a 4-inch, 90-degree duct elbow to the outlet port on the side of the vent fan housing. Aim the elbow straight up and secure it to the port with foil duct tape. Remove the knockout hole on the side of the fan’s housing and attach a cable connector. Slide the four metal brackets into the tabs protruding from the sides of the vent fan. Set the vent fan down into place between the joists, centered on the ceiling hole. Tip: Use foil duct tape; unlike fabric duct tape, it won’t deteriorate over time.  
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Install Bathroom Fan

Shopping for a Quiet Fan A quiet fan has a “sone” rating between .5 and 1.5. A sone is a measure of loudness. The lower the number, the quieter the fan. By contrast, typical low-cost bath fans range from 2 to more than 5 sones (which you can easily hear in the next room). Select the ventilation capacity of the fan that fits the size of your bathroom. To quickly estimate the cfm needed (cubic feet per minute, or how much air a fan moves), a “rule of thumb” is to multiply the length of your bathroom by the width and round up. For example, an 8 x 10-ft. (80 sq. ft.) room would need a vent rate of 80 cfm and would require an 80-cfm fan. Quiet fans have better motors (rated for continuous operation), heavier-duty housings and larger ducts, usually 4 in. They cost considerably more than standard fans. It’s quiet!
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Install Bathroom Fan

Shopping for a Quiet Fan A quiet fan has a “sone” rating between .5 and 1.5. A sone is a measure of loudness. The lower the number, the quieter the fan. By contrast, typical low-cost bath fans range from 2 to more than 5 sones (which you can easily hear in the next room). Select the ventilation capacity of the fan that fits the size of your bathroom. To quickly estimate the cfm needed (cubic feet per minute, or how much air a fan moves), a “rule of thumb” is to multiply the length of your bathroom by the width and round up. For example, an 8 x 10-ft. (80 sq. ft.) room would need a vent rate of 80 cfm and would require an 80-cfm fan. Quiet fans have better motors (rated for continuous operation), heavier-duty housings and larger ducts, usually 4 in. They cost considerably more than standard fans.
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Determine the correct CFM rating for your bathroom. The first thing you need to do when installing a new bathroom fan is determine the CFM rating for your bathroom, so you can buy the appropriate strength fan. CFM stands for “Cubic Feet per Minute” and refers to how much air the fan can move per minute. Small bathrooms will need low CFM fans, while larger bathrooms may require fans with a much higher CFM. To calculate the CFM for your bathroom, multiply the room’s cubic footage (length x width x height). For example, if your bathroom measured 120 square feet, you would multiply that by the height of the ceiling (say 8′) to get 960. THEN divide by 7.5 to get a CFM rating of 128. You will find the CFM rating of a new fan printed on its box.
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Draw a mark on the bathroom ceiling where you’d like to install the vent fan. For optimum performance, locate it between the shower and the toilet. Use an extra-long, 3/8-inch-diameter spade bit to bore a reference hole through the ceiling and into the attic. Climb into the attic and clear away any insulation from around the hole. Now use the reference hole to determine the exact position of the fan. Measure the vent fan housing. Try to position the vent fan directly between two joists near your reference hole. Take into account any nearby pipes or other obstructions. Note the final position of the vent fan in relation to the reference hole.  
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A quiet fan has a “sone” rating between .5 and 1.5. A sone is a measure of loudness. The lower the number, the quieter the fan. By contrast, typical low-cost bath fans range from 2 to more than 5 sones (which you can easily hear in the next room). Select the ventilation capacity of the fan that fits the size of your bathroom. To quickly estimate the cfm needed (cubic feet per minute, or how much air a fan moves), a “rule of thumb” is to multiply the length of your bathroom by the width and round up. For example, an 8 x 10-ft. (80 sq. ft.) room would need a vent rate of 80 cfm and would require an 80-cfm fan. Quiet fans have better motors (rated for continuous operation), heavier-duty housings and larger ducts, usually 4 in. They cost considerably more than standard fans.

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