The vent fans in our bathrooms make loud clapping noises when it's windy. I can open/close the doors to the bathroom quickly and hear the flap clapping because of the pressure change. Is this something I should be concerned about? The house is less than a year old and I'd like to take it up with the warranty department if it is going to cause an issue. I've never had this issue in any other place I've lived.

Here is a video of the clapping during windy conditions.

  • This is quite normal.
    – Hot Licks
    May 7, 2022 at 18:37
  • Disagree. What's the cap look like outside? Is it made out of metal and has a spring loaded damper, or it's plastic and half of it's missing?
    – Mazura
    May 7, 2022 at 23:08
  • @Mazura I need to take a look. I've been hesitant to get a ladder as my back's been bugging me but I clearly need to go take a look. Thank you!
    – Shrout1
    May 8, 2022 at 4:03

1 Answer 1


There is nothing wrong, when you have a small space like a bathroom and you open the door quickly the pressure is enough to open the back draft dampers in the exhaust fan. The same thing happens when you turn on the fan the damper(s) open allowing air out. If a high wind blows across the external duct it can cause noise but that is also normal and nothing a warranty could do anything about. After some time you get used to it adding construction cloth around the opening can help reduce the noise but is an extra cost. Construction is a wire grid that is wrapped around the openings like this to keep critters out and it also reduces whistling,

  • I forgot about the back draft dampers in the exhaust fan (which is what that must be if it's so loud, +1). I thought for sure from the title it was crappy plastic flappers on the outside which should be made out of metal and have a spring, instead of three slats of plastic and no springs. - I'd pull that damper out and/or make sure I had a good flapper outside. It's not uncommon to be missing one or more of those three slats...
    – Mazura
    May 7, 2022 at 23:05
  • Ok thanks all - I need to take a closer look before jumping to any conclusions. Appreciate the info!
    – Shrout1
    May 8, 2022 at 4:02

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