Heavy Traffic: The room is in constant use. It may be a high-moisture room, like a bathroom or laundry room. Or it may be a room where spills are frequent, such as a kitchen.
Normal Traffic: The room is used often. It may be a room prone to moisture like a bathroom or where spills are frequent, such as a kitchen.
Light Traffic: Few people use the room regularly, like a formal dining room or guest bedroom. This room is not prone to moisture.