Stop Water Stains on the Ceiling in Bathrooms

I finally had someone explain to me why we were getting staining on our ceiling around the exhaust vent in the bathroom. My wife and I had thrown around a few different ideas like:

  • improper seals around the roof vent
  • insufficient vent strength
  • condensation in the attic
  • improper ventilation
  • leaking pipes

After the bathroom ceiling fan starting to rattle on the weekend I decided it was time to replace the exhaust fan. I figured while I was replacing one fan I might as well replace them all as they are all old and they don’t actually clear the steam from the bathrooms during showers.

When I was there purchasing the new exhaust fans I was told why our current fans and ventilation is leaving a stain on the ceiling. The problem is that the ventilation is not insulated. This causes condensation to form on the outside of the pipe and run down the pipe to the bathroom ceiling.

Then I install the new bathroom exhaust fans I will be insulating all the exhaust vents in the attic with either spray foam insulation like in the photo from the Ask the Builder article about bathroom fan ventilation, or by wrapping it in standard pink batt insulation.

The basement vent so far has proven difficult to put in as I need to work from underneath between the basement ceiling and the main floor. There isn’t much room to work in and it’s been hard to attach the ducting to the fan in the limited area before attaching the electrical. I’m hoping that working in the attic for the top two fans will be easier, but I haven’t been in the attic for our new house yet, so we will see what is up there soon enough …

4 Replies to “Stop Water Stains on the Ceiling in Bathrooms”

  1. Mom

    I don’t know if I like the picture in my head of you working between floor and ceiling. Please don’t get stuck!

  2. Cameron Byrne

    I think I would go for the pink batt insulation as it is known to reduce transmission of noise. A fiberglass batt insulation can also be a smart choice since it’s fairly inexpensive and easy to install.

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