Seams should last as long as the Sunbrella fabric itself. Using cheap imported thread defeats the purpose but is frequently used by other online cushion manufacturers. We use Gore UV on all our high end cushions such as OW LEE, Brown Jordan, etc.) and it's offered as an upgrade to all other cushion types. Gore UV carries a lifetime warranty and should outlast the fabric itself. In blazing sun, Gore UV is highly recommended. In less severe sunny areas our standard USA grade thread usually lasts for years.