Waterproofing Concrete Control Joints
• Sealant: Polyurethane sealant.
• Backer rod: Closed-cell polyethylene foam.
Basic Rules for Joint Design
1. The joint size shall be no smaller than ¼ inch.
2. The joint size shall be no larger than 1 inch.
3. The joint opening shall be a minimum of four times the anticipated movement rate.
Basic Rules for Sealant Design
1. The material thickness shall be no less than ¼ inch.
2. For joints up to ½ -inch wide, the depth of the material shall equal the width of the material.
3. For joints wider that ½ inch, the depth of the material is equal to the width of the material.
4. The maximum recommended width is 1 inch.
5. The maximum recommended depth is ½ inch.
Determination of Number and Spacing of Joints
The anticipated substrate movement is determined by the coefficient of expansion, the length of the material span, and the joint width.