Single ply roof guarantees typically cover 15-20 years, but the actual roof can...

https://www.random-bookmarks.win/single-ply-roof-guarantees-usually-15-20-years-cover-product-defects-but

Single ply roof guarantees typically cover 15-20 years, but the actual roof can last 25-40 years with proper care. Guarantees focus on the material’s performance, not the whole system or wear and tear