We got a new bathroom constructed in the basement last year. On top of the ceiling of the washroom runs the duct and I think the water pipes too. I got it checked and was told that the heating and cooling is OK. So probably it is a plumbing issue. I observed that each time the washer and the dryer is on while I am doing the laundry which is located on the floor above the new washroom, condensation happens which is visible on the ceiling. I was suggested to keep the washroom door open when I do the laundry and even to turn on the exhaust. I am following these instructions but still see that the ceiling is moist and I can see visible signs of deterioration. Not sure what to do.

 

Welcome to the forums!
can you post a pic? http://www.doityourself.com/forum/el...-pictures.html

 

Is this new bathroom being used for showering or bathing?

It is possible that the cold water running through the pipes cools the ceiling and causes water to condense. While this is possible I'd consider it rather unlikely and would probably only happen when the humidity in the room was super high.

 

I wonder if there might be a hole or break in the dryer vent. There's a lot of hot, moist air from the dryer, which needs to get outside. I'd be concerned that maybe some of that hot air is ending up in the joist bay above the ceiling, cooling, and condensing there.

A picture may help... but I think you may need to open up the ceiling a bit to see what you're dealing with and where the water is actually coming from.

 

Thanks for your reply. I will get the ceiling opened up and try to post the pictures.