I got a call from an apartment manager; one of the units had a soft wet spot in the bathroom ceiling near the exhaust fan. I verified that there was moisture in the drywall and that it was discolored. Since it was an upstairs unit I was able to get into the attic crawl space. I knew from experience that there was no plumbing or drain lines in that area.
I assumed that since it was near the exhaust fan in the bathroom ceiling, there must have been a leak in the roof boot. After crawling up and looking at the discoloration under the insulation, there was no evidence of a leak at the roof.
So where was the water coming from? It wasn’t a stream of water but the area was moist. After climbing down and talking to the tenant about the use of the fan, I learned some important information.
The tenant was in the habit of shower with hot water for up to 2 hours a day, every day. They ran the fan to get rid of the steam. The warm moist air traveled up the vent, which was very cold and compensated within the vent stack. The water droplets gathered at the elbow of the vent and dripped onto the top of the sheetrock ceiling.
Sometimes, our own personal habits can lead to moisture problems. Knowing what causes these sorts of problem may lead to a change in behavior, which will help correct the problem with moisture. If you are experiencing a moisture problem, call someone who has experience in dealing with moisture problems.
El Dorado County