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

https://www.bestbookmarks.win/a-single-ply-roof-guarantee-usually-covers-15-20-years-but-the-actual-service

Single ply roof guarantees usually cover 15-20 years, but the actual roof can last 25-40 years with proper care. Guarantees protect against defects, not wear and tear or poor maintenance