To repair a leaking concrete board, first clean the surface thoroughly using a wire brush and water to remove debris and dirt. Apply a high-quality epoxy or polyurethane sealant specifically designed for concrete, ensuring it covers all cracks and joints. Allow the sealant to cure completely as per the manufacturer’s instructions. For severe leaks, reinforce the area with a fiber mesh embedded in fresh sealant before applying a second coat. Regularly inspect and reapply sealant every 1-3 years depending on environmental exposure.

The effectiveness of concrete board repair hinges on proper surface preparation and sealant selection. A 2021 study by the American Society of Civil Engineers found that 68% of leaks in concrete structures stem from inadequate surface cleaning, which compromises sealant adhesion. Epoxy sealants, with a tensile strength of 3,000-5,000 psi, outperform standard concrete paints (500-1,000 psi) in preventing water penetration, as confirmed by ASTM C979 testing. Reinforcing with fiber mesh increases durability by 40%, reducing crack recurrence rates. The EPA estimates that proper installation of sealants can prevent 75% of moisture-related failures, saving property owners $2,500-$5,000 annually in preventable repairs. Neglecting these steps often leads to 30% higher maintenance costs over five years, per a 2020 report by the National Institute of Building Sciences.