The most obvious sign that you need basement waterproofing is a flooded basement. However, there can be smaller signs to let you know there is a leak before it becomes a full flood. If you see water puddles on the floor, water stains on the floor or walls, condensation on windows or doors, swelling or warped doors, or mold, it’s a good sign you need waterproofing. A musty smell that won’t go away is another sign.