How to install a bathroom exhaust fan through the roof

Written by michael straessle
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The best method for venting an exhaust fan in the bathroom is through the roof. This is because heat and vapours rise. The fan helps the odours and other vapours move in the same direction up and out of the bathroom. Exhaust fans are available in different sizes, so choose the one right for the size of the bathroom in which it will be installed. Inspect the attic area before purchasing the needed material to ensure a proper fit and to maximise the benefit of the exhaust fan. Exhaust fans also prevent damage to the wood and paint caused by moisture created by a hot shower.

Skill level:

Things you need

  • Keyhole saw
  • 2-by-4-by-14½-inch lumber
  • 1¼-inch drywall screws
  • Hole saw

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  1. 1

    Locate the area of the bathroom ceiling for the exhaust fan and mark it. Next, locate the ceiling joists and determine their relation to the desired location for the fan.

  2. 2

    Turn off the breaker to the existing fan in the electrical panel, if applicable. If not, turn the main breaker off.

  3. 3

    Trace the pattern of the exhaust fan onto the ceiling and cut it out with the keyhole saw. Place the fan in the hole to be certain of a good fit.

  4. 4

    Climb into the attic and secure the 2-by-4 between the ceiling joists over the hole for the fan with the drywall screws. Climb down out of the attic and secure the fan to the 2-by-4 with the drywall screws.

  5. 5

    Climb into the attic and feed one end of the electrical wiring through access hole in the fan. Run the wire over to the wall where the house electrical panel is located and feed the other end of the wire into the panel.

  6. 6

    Connect the first section of the exhaust pipe to the fan according to manufacturer's instructions. Install the remaining pipe to just below the roof and cut a hole for the pipe with a hole saw.

  7. 7

    Install the last section of pipe through the roof. Connect the wire to the fan according to manufacturer's instructions. Repeat this at the electrical panel with the breaker, install the new breaker into the panel and turn the main breaker on again.

  8. 8

    Install the exhaust pipe boot on top of the roof according to the manufacturer's instructions.

Tips and warnings

  • Provide adequate lighting in the attic and bathroom while the electricity is off.
  • Use the same brand of breakers already installed in the electrical panel.
  • Never work with live electricity.
  • Wear goggles, face mask and gloves while working in the attic.

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