Sweaty windows, mold-covered walls, peeling wallpaper and a heavy, musty odor are all symptoms of excessive moisture buildup and a poorly ventilated home. So where does all this moisture come from? The washing machine, clothes dryer, shower, wash basins, kitchen sink, dishwasher and stove are only a few sources. Even breathing puts moisture in a home's interior. Water vapor comes from many sources, and without proper ventilation to the outside, it accumulates day after day doing damage, creating odors and generally becoming a raging science experiment. It can be unhealthful, too. The best way to handle this problem is with an automatic exhaust fan vented by flexible or rigid pipe to an exhaust port on the roof or an exterior wall. It never should discharge directly into an attic or enclosed crawl space where the moisture will again collect and cause even more damage -- because it's hidden away and out of sight. And that's the On The House tip for today.