Humidity in my house right now 13%, which is normal during winter. I have cathedral ceilings with no attic. It is an older, very large, 100% wood house, log cabin style. I ran 1 gallon humidifier for a week and now have water dripping exactly above the humidifier. It drips like one drop every 10 min at night and more often during day time. It is 21F outside. The roofer had said the roof is fine. Is it because of the humidifier? But the house is huge and I would think the moisture would spread around the house, not accumulate somewhere. The distance between the floor and the ceiling is also substantial. What is happening, please help.

  • Moisture doesn't spread around the house (at least not quickly) unless air spreads around the house. What type of heating system do you have? What is the water condensing on? More information, please.
    – isherwood
    Mar 9, 2021 at 14:20
  • @isherwood it is a heat furnace, almost brand new.
    – Mac Book
    Mar 9, 2021 at 14:22
  • @isherwood Forced Air heating system.
    – Mac Book
    Mar 9, 2021 at 14:24
  • 3
    Think maybe a cold spot on ceiling, less/no insulation in that spot. Does moving the humidifier move the dripping?
    – crip659
    Mar 9, 2021 at 14:32
  • 1
    Quite a few males would also have trouble explaining. With humidifier off for a week and still dripping, think it is time for another roofer or similar person.
    – crip659
    Mar 9, 2021 at 14:47

2 Answers 2


I bet your ceiling is cold.

Consider my cold drink on a hot day. Humidity has spread around the clubhouse. The outside of my glass is dripping wet and I must use a coaster. Why does the humidity stop just on my glass and not breeze on by? It is because my glass is cold, and passing humidity that bumps into it condenses into water.

So too your roof. You have a cold spot for whatever reason. Ambient humidity in the house stops there and condenses. You could try to address the spot, or give up on humidifying the great room and concentrate on humidifying bedrooms.

  • But even with a humidifier running non stop for a week, overall humidity in the house won't reach even 25%. This is the first time in my 10 years living in the house. New roof-6 years ago.
    – Mac Book
    Mar 9, 2021 at 14:42
  • Think this is more roof/space under roof problem than humidifier problem. Some snow has probably gotten in and is now melting slowly. Humidifier was just on at wrong time, snow started melting. If want can turn it on again, will not make any difference, would move so not under leak/drip.
    – crip659
    Mar 9, 2021 at 19:01
  • Humidity isn't the only factor in play here. The dew point is the critical number relative to condensation. So even low humidity can produce condensation when the air strikes a surface area with a temp at the dew point or below. But I'm with @crip659 the humidifier may not be the problem.
    – HoneyDo
    Mar 9, 2021 at 20:36
  • @crip659 How some snow can get in (where?), if it is A shape roof with no attic? Inside beams support the cathedral ceiling. And it drips from one spot only.
    – Mac Book
    Mar 9, 2021 at 21:31
  • You can figure it out pretty quick. Turn off the humidifier and see if it keeps dripping.
    – Willk
    Mar 9, 2021 at 21:41

After all it was the humidifier. One week non stop moist stream toward the ceiling did create the described scenario. It took a long time for the dripping to stop.

  • 1
    I moved my bathroom fan to above the shower, and I have no attic entrance so I used the hole from the old fan to get up and do the work. It made it hard to properly insulate. During showers in the winter, water droplets form and drip in that area because it wasn't insulated properly.
    – rtaft
    Dec 8, 2021 at 12:43
  • Thanks for posting the followup!
    – Willk
    Dec 8, 2021 at 20:02

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