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

https://andreocln282.lucialpiazzale.com/pvc-single-ply-roof-lifespan-is-30-years-realistic

Single ply roof guarantees usually cover 15-20 years, but the roof can often last 25-40 years if looked after properly. The guarantee mainly protects against manufacturing faults, not wear and tear or poor maintenance