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

https://www.random-bookmarks.win/single-ply-roof-guarantees-often-15-20-years-cover-materials-and

Single ply roof guarantees usually cover 15-20 years, but these membranes often last 25-40 years in real life. The guarantee is about the manufacturer’s promise if something goes wrong, not how long the roof will physically hold up