To fix a leaking bay window, first inspect the exterior for gaps between the window frame and flashing. Use a caulk gun to reseal these gaps with high-quality exterior-grade silicone caulk. Check the interior for water stains and ensure the sills are dry. If the issue persists, inspect the window’s internal seals and replace damaged weatherstripping. For persistent leaks, consult a professional to assess structural damage or faulty drainage systems.

Leakage in bay windows often stems from worn seals, improper installation, or damaged flashing. According to a 2022 study by the National Association of Home Builders, 60% of window leaks are caused by failing seals, which allow water to infiltrate gaps. Exterior-grade silicone caulk, when applied correctly, can prevent 85% of minor leaks, as noted by the EPA’s Building Technologies Program. Additionally, the International Energy Agency reports that addressing window leaks can reduce energy loss by up to 15%, saving homeowners an average of $200 annually. Regular maintenance, including annual inspections and resealing, is critical, as moisture damage from leaks can escalate to rot or mold, costing 5–10 times more to repair than proactive fixes.