I have black marks around the bottom of my windows due to the humidity in the home from the hot tub in the basement.I have exhausted the hot tub room to the attic with a 600 cfm fan into a 6inch duct. What do I do about black stains on the wood, at the bottom of the windows, now that the humidity is gone. Do I rap the duct with insulation and plastic once in the attic, and what type of ducting is best up there and the manner that I get the air out of attic, roof vent side vent.
Answer:
The black stains will come out with wood bleach once the wood has dried but it's quite a bit of work. Before you do anything, you have to vent the duct to the outside because there is a lot of moisture going into the attic right now. The duct should be well insulated (R-28 bats wrapped and taped all around it full length) and it doesn't really matter whether it goes through the soffit or the roof but outside it must go.
