General concrete crack and joint treatment detail courtesy of American Hydrotech, Inc.
There are two ways to waterproof joints and cracks in concrete for waterproofing applications. There is the traditional method of applying sealant in the joint or crack in accordance with proper sealant depth to width ratio of 2 to 1. For joints over 2 inches in width, an expansion joint material is required. Cracks over 1/4 inch in width should be treated as control joints.
Another method is to apply the waterproofing manufacturer’s materials over these locations. For joints less than 2 inches in width and cracks less than ¼ inch in width, some waterproofing manufacturers require the application of their flashing or reinforced material, which is applied over the crack or joint.
It is important that the concrete surface is properly cleaned off and free of all loose contaminants for adequate adhesion. The reinforcement material shall be applied in accordance with the manufacturer’s requirements for proper adhesion, which may require application in adhesives, self-adhered sheets or hot bitumen.
