Another consideration. Mold grows where there is moisture, and a dryer vent sends plenty of moisture into the air. Your clothes dryer may be in the basement, an alcove on the main floor, in the bathroom or the kitchen, but regardless of location, mold spores get into the air and expose you and your family to a toxic environment. Dangers of mold include breathing problems, stuffiness and skin irritation. I'd just cut the hole in the side of the house and put in the vent. There are better safe ways to humidify your home.