Building Condensation

[YoBenny]

I am at a park on the Suwannee River in Florida. We call a watershed like this a creek at home, but that's on the banks of the Mississippi. It's pretty dry here, sand is dry, leaves, no real visible moisture anywhere on anything.
My weather station says 41% humidity which to me is pretty dry. Temp is 78°
But the inside of the park rest rooms are dripping wet. Literally dripping. Commode seats all wet. Mirrors fogged over.
Nobody has used the showers in days. No use at all really. There's a roof fan on top pulling the air through them.
I just don't get it. Even the sink counters are sopping wet, all day, all night.
Any ideas why this is happening?

 

[cic317]

I would guess the fan is not big enough to pull outside air to vent or the fan isn't vented to exterior. The later is very common find in attics

 

[YoBenny]

I would guess the fan is not big enough to pull outside air to vent or the fan isn't vented to exterior. The later is very common find in attics

The fan is mounted directly to outdoor vents around it in its own little house on top, and it is loud like its decent size too. The park ranger told me that they can't figure it out either, he said the fan actually makes it WORSE in the winter.

 

[Rene T]

I wonder if they have a small leak in one of the hot water pipes causing steam to infiltrate the bath house. even if you can’t see the leak or any steam it still may be putting out a lot of moisture. I wonder was the moisture level is.
Is it more than one bath house with this issue?

 

[YoBenny]

I wonder if they have a small leak in one of the hot water pipes causing steam to infiltrate the bath house. even if you can’t see the leak or any steam it still may be putting out a lot of moisture. I wonder was the moisture level is.
Is it more than one bath house with this issue?

They have tankless water heater installed so there is no constant source of hot water until you use it.
It's cinder block and well painted so not holding moisture in the walls. Floor is tile with grout, I wondered if the grout was holding moisture but there is simply way too much of it for the grout to hold. It's condensing out of the atmosphere for some reason when it is not doing it anywhere else.

 

[SuwanneeDave]

Speaking as someone who lived in N Fla many years and still has property there, I believe that at this time of year it has to do with the temperature and humidity swings between daytime and nighttime, along with the thermal delay of the block walls. During the day the air heats up, lowering the relative humidity (remember that it is relative, the water vapor is still there). During the night the reverse occurs except that the block walls take hours to cool down. Sometime in the morning the block walls are cooled down but the moisture laden air is warmer, leading to condensation of the walls and things attached to them. When it gets colder, or hotter in the summer it will probably not occur.

 

[Ray-IN]

Speaking as someone who lived in N Fla many years and still has property there, I believe that at this time of year it has to do with the temperature and humidity swings between daytime and nighttime, along with the thermal delay of the block walls. During the day the air heats up, lowering the relative humidity (remember that it is relative, the water vapor is still there). During the night the reverse occurs except that the block walls take hours to cool down. Sometime in the morning the block walls are cooled down but the moisture laden air is warmer, leading to condensation of the walls and things attached to them. When it gets colder, or hotter in the summer it will probably not occur.

Sounds logical to me.