No matter what, you can't leave low spots in bathroom vent tubing in the attic.
Every now and then the bathroom vent has a long way to go as it traverses an attic space.
The longer it is, the more condensation can develop.
In this case the tubing runs quite a distance, so the on bathroom has insulated vent tubing.
That is to control condensation.
But it still develops.
At the opening on the roof. In winter months condensation will develop there and come back down the tubing.
However, if there is a low spot it will collect there!
It will get heavier.
I have seen them so full of water they tear and drip.
I have also seen them get so heavy they fall down from the opening, spilling their water onto the ceiling.
This is a pre-drywall inspection, so this is good to catch now. Fixed it will never be a problem.
Once a client called on me to investigate why a stain had developed on his ceiling when it had not been raining or snowing. Going into the attic space I was able to see where the insulated bathroom vent tubing had come loose, and, being full of water, drained right into a bedroom ceiling!
My recommendation: be sure there are no low spots in any vent as it will affect air flow. But especially in an attic space. Any low spot is an invitation to water to collect and enjoy itself! And it will, until given the opportunity to leave.
Jay Markanich Real Estate Inspections, LLC
Based in Bristow, serving all of Northern Virginia.
Office (703) 330-6388 Cell (703) 585-7560