Single ply roof guarantees usually cover 15-20 years, reflecting the...

https://redditchstandard.co.uk/lifestyle/how-long-does-a-single-ply-membrane-roof-really-last-a-building-owners-guide/

Single ply roof guarantees usually cover 15-20 years, reflecting the manufacturer's confidence in the material under ideal conditions. But in reality, with proper care, these roofs often last 25-40 years