Single ply roof guarantees usually cover 15-20 years, but these roofs often...

https://www.yankee-bookmarkings.win/single-ply-roof-guarantees-typically-cover-15-20-years-but-these-roofs-can

Single ply roof guarantees usually cover 15-20 years, but these roofs often last 25-40 years in real life. The guarantee mainly protects against material defects, not wear and tear or maintenance issues