Single ply roof guarantees typically last 15-20 years, but the roof itself can...

https://www.first-bookmarkings.win/single-ply-roof-guarantees-often-cover-15-20-years-but-the-real-service-life

Single ply roof guarantees typically last 15-20 years, but the roof itself can often go 25-40 years with proper care. Guarantees cover materials and workmanship, not wear and tear or damage over time