The replacement cycle of system-window sealant depends on type, conditions and quality. EPDM or silicone-rubber sealants can last 15–30 years, while PVC-rubber or rubber-plastic blended sealants about 10–15 years. Specifically: EPDM sealant typically 20–30 years (affected by climate, environment and quality); silicone-rubber 20–30 years (varies with quality, conditions and installation); PVC-rubber about 10–15 years; rubber-plastic blended about 10–15 years. The cycle is not fixed — if the sealant ages, cracks or loses sealing, replace it promptly to maintain window performance.