Why is Waterproofing Necessary? Water infiltration through cold joints can lead to a host of problems, including mold growth, concrete degradation, and structural instability. These joints are weaker points in the concrete that require special attention to prevent water infiltration. The seal must be capable of accommodating the anticipated joint opening and closing due to static reasons or temperature changes. To effectively. bility and life cycle expectancy. Sealing compounds for expansion joints should alwa s be made from elastic materials. Movement joints up to a width of 1.