Single ply roof guarantees often cover 15-20 years, reflecting manufacturer...

https://www.bookmark-zulu.win/single-ply-roof-guarantees-usually-cover-15-20-years-but-these-membranes-often

Single ply roof guarantees often cover 15-20 years, reflecting manufacturer confidence in their product’s performance under ideal conditions. But with good care, these roofs can last 25-40 years