Single ply roofing guarantees typically span 15-20 years, covering material...

https://daisydustmaid.com/overlay-vs-full-replacement-for-a-single-ply-roof-when-does-overlay-make-sense/

Single ply roofing guarantees typically span 15-20 years, covering material defects but not the entire roof’s life. In reality, with good care, these roofs can last 25-40 years