Moisture- Should I vent roof for my small building or buy fan? Conflicting answers.

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Small gap around both electric blue boxes. Also, hole for wires could be filled to make smaller. Good improvements?
 
alanrudy said:
I have a 120sq ft shed/building that insulation and drywall was added flush (instead of flat ceiling) to the ceiling to maximize height inside (please see pictures for hopefully good description). I had an issue with few drops of water under the lights pictured when I took them off. First, I thought the roof was leaking but after running a hose on the roof with no leak, the only other thing I'm thinking it could be is condensation.

Condensation forms when warm wet air meets a cold (below dew point) surface.
Empty unused building almost never have a problem with condensation.
Buildings used by people, who breath and sweat do.
How often is the building occupied? What is it used for?
Click to expand...
 
It will be used for a den/office space, but it hasn't been occupied much at all yet even though this issue has already arisen due to the issues nealtw addressed.
 
The other side of the story is, warm air holds more moisture than cold air.

Homes and other places that are heated on a part time basis, are subject to condensation when the heating is turned down or off.

Often windows or other surfaces are running in water due to people turning off their heating, or closing their blinds or curtains - during the heating period warm air wafts past the surface keeping it warm (above dew point) when the heating is turned off, or the blinds are closed the air in the recess cools and condensation forms.

This is why it is unusual to have condensation in an unused unheated room, the air holds just enough water vapor for its temperature and the surfaces are at air temperature, therefore, no dew point.
 
What’s the reason for insulating an unheated / uncooled (unconditioned) building?
 
I wanted to make the 120sq ft structure as much as a living space/den/office as a home would have so I thought insulation/drywall was the way to go. I guess the combo of the small space, cold weather, and closed window reeks havoc.
 
The reason asked was I started a similar project last fall and your thread has me thinking a little. In my case the room is an addition that was attached to my garage a 14x14 space and I am sealing it all up as I want that to be an all season workshop. I have an air con unit out there and small space heater. But I won’t be using ether unless I’m out there working. So most so the time they will be prepped as a conditioned space but not conditioned. In my case I have an outside door but also an inside door to the garage I can leave open to vent the room.
 
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