Open Floor Plans With Walkout Basements - There are several approaches to help prevent moisture damage issues at a basement. The very first rule of thumb isn't a dirt basements. Though these are somewhat less common in this day in age, it's a good idea to point out that dirt floors not only hold a huge amount of moisture but also can give off a variety of gases. When building a basement, make certain that you have a floor drain using a trap installed at the lowest point of the floor.
Without a floor drain, any water that is spilled inside can't get out. If needed, install a sump pump and ensure that the sump cover is tightly sealed. Sump pumps are often used where flooding because of a high water table may be a problem. Additionally, waterproof the exterior of the base walls and put in a perimeter drainage system. An often overlooked problem in bathrooms is moisture that comes from humidity.
The easiest way to control humidity would be to exhaust water vapor generated in the home to the exterior. Signs of high humidity include condensation on windows, pipes or other surfaces as well an overall sense of moisture from the atmosphere, dampness, and smells. Many times, the humidity will be brought on by exposing the basement to outside air (open windows), having wet laundry hung to dry from the basement, keeping firewood from the basement, and/or a dryer vent that exhausts inside.
In summer, use a portable dehumidifier or air conditioning to reduce humidity. In warm, humid weather, keep basement windows closed. Run the furnace fan continuously to circulate home air. The key to keeping basement humidity low would be to keep them well ventilated and to keep extra moisture from the basement.