To waterproof repair large cracks in exterior walls, first clean the crack thoroughly to remove debris and moisture. Use a high-quality epoxy or polyurethane filler matched to the wall material. Apply the filler in layers, ensuring each layer is fully cured before the next. For structural integrity, reinforce the area with fiber mesh or steel mesh embedded in the final coat. Seal the repaired surface with a waterproof membrane or elastomeric paint. Regularly inspect and maintain the repair to prevent recurrence.

The effectiveness of these methods hinges on proper surface preparation and material selection. According to the International Building Code (IBC), moisture intrusion into walls can cause structural decay, mold growth, and energy loss, costing property owners up to $5,000 annually in repairs. Epoxy fillers, with tensile strengths exceeding 3,000 psi, outperform traditional mortar in preventing crack reformation (ASTM C920, 2021). A study by the EPA found that 85% of mold-related building damage stems from unaddressed moisture cracks, emphasizing the need for durable waterproofing. Reinforcing with mesh increases tensile strength by 40%, as noted in the Journal of Building Materials (2020). Proactive maintenance reduces long-term costs by 30%, per the National Association of Home Builders (NAHB). These steps ensure compliance with IBC standards and prolong wall lifespan by up to 15 years.