Single ply roof guarantees typically cover 15-20 years, but the real service...

https://www.bookmarking-keys.win/a-single-ply-roof-guarantee-usually-covers-15-20-years-but-the-roof-itself-can

Single ply roof guarantees typically cover 15-20 years, but the real service life can stretch to 25-40 years with proper care. The guarantee mainly protects against material faults, not wear and tear or damage from poor maintenance