Installing Bathroom Fan Without Attic Access

Installing Bathroom Fan Without Attic Access

Step One // Installing 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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Installing Bathroom Fan Without Attic Access

Install the Fan Step 1 Some fans require setting the duct connector in the ceiling first. Hold the housing up, lining up the connector with the slots, and slide the housing into the hole. Step 2 If you don’t have an attic or access to your attic, check your manufacturer’s instructions for recommendations. Typically, you would need to frame part of the hole. Cut a 2-by-4 to fit between the ceiling joists and secure with screws. Remember to keep the vent side clear. Step 3 Keeping the housing level and square with the joists, drive screws through the mounting holes into the joists. Step 4 The next few steps should be completed in the attic. Skip this step if you added extra 2-by-4 bracing between the joists. From the attic, set a board to kneel on near the fan. Attach the brackets to the joists. Then connect the brackets to the fan body with screws. Step 5 Attach the ducts to the connector with HVAC tape. Step 6 Hook up the wiring by first removing the junction box cover. Then connect the house wires to the fan wires: ground to ground, neutral white to neutral white, and hot black to hot black. Step 7 Replace the junction box cover and turn on the power. If the fan sounds loud like something isn’t right, turn off the power and check that it’s mounted securely and level. If it sounds ok, add the mounting springs and push the cover into place.
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Installing Bathroom Fan Without Attic Access

Replace Bathroom fan w/o attic access The fan in our bathroom makes noise. It is a 20 year old builder grade unit that came with the condo. Our bathroom is in the middle of the house, no window. When we removed the fan assembly and tested it with a regular outlet, there was no noise. So, we think it is the fan housing rattling. We cannot find a direct replacement, so we would like to replace it with a newer model, more CFM and less noise. However, we have no access to the attic. The newer model has about the same size housing as the existing one which is nailed to a ceiling joist, but not exactly the same ceiling cutout. We can not even remove the current fan housing without cutting into the ceiling. What is the best way to replace the fan housing?
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Installing Bathroom Fan Without Attic Access

Step Two // Installing 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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Installing Bathroom Fan Without Attic Access

Installing a ceiling fan in an area where you have no attic access is a relatively easy task if you have the right materials and you take your time. It helps if there is a circuit already available in the place where you wish to install your fan, but it’s important to note that you can’t simply take down a light fixture and replace it with a fan. If the circuit is already there, installing a ceiling fan without attic access takes about an hour.
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Installing Bathroom Fan Without Attic Access

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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Installing Bathroom Fan Without Attic Access

Step Five // Installing 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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Installing Bathroom Fan Without Attic Access

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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The fan in our bathroom makes noise. It is a 20 year old builder grade unit that came with the condo. Our bathroom is in the middle of the house, no window. When we removed the fan assembly and tested it with a regular outlet, there was no noise. So, we think it is the fan housing rattling. We cannot find a direct replacement, so we would like to replace it with a newer model, more CFM and less noise. However, we have no access to the attic. The newer model has about the same size housing as the existing one which is nailed to a ceiling joist, but not exactly the same ceiling cutout. We can not even remove the current fan housing without cutting into the ceiling. What is the best way to replace the fan housing?
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Show us a bathroom with peeling paint, rotting window trim and a mold problem and we’ll show you a bathroom without a vent fan. Bathrrom ventilation is the best way to prevent moisture-related problems, such as the growth of mold and mildew. Here, This Old House general contractor Tom Silva shows the proper way to install a fan, running the exhaust duct into the attic and through a sidewall to the outdoors. Other venting options includes running the duct up through the roof or down through the soffit. Note that the fan must always exhaust to the outdoors; never allow the duct to simply blow into an attic, crawlspace or other enclosed area, or you’re certain to fail inspection.
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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.

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