Single ply roof guarantees of 15-20 years cover material and workmanship, but...

https://www.alphabookmarks.win/single-ply-roof-guarantees-usually-15-20-years-cover-workmanship-and

Single ply roof guarantees of 15-20 years cover material and workmanship, but the actual service life can be 25-40 years with proper care. Factors like weather, maintenance, and installation quality all play a role