Got a moist and wet basement wall? Is it coming from outside or is it a leak at all? Today in dampness-detection I, we ask, "is it an inny or an outty"? To find the source of moisture use a hair dryer to dry a patch of wall about 15-inches square. Then tape a 12-inch square of plastic film in the center of the dry area (even a piece of plastic grocery bag will do). Tape all four sides, then wait two days and check the plastic. If the under side is wet but the top is dry, the seepage is from outside. If the top side is wet and the under side dry, it's condensation from inside the house. Once you've detected where it's coming from, you can work on correcting the problem. Tomorrow in moisture-detection II, we have another slick trick for finding and fixing a sneaky outside leak. Stay tuned and dry. And that's the On the House tip for today.