Single ply roof guarantees typically cover 15-20 years, but with proper care,...

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

Single ply roof guarantees typically cover 15-20 years, but with proper care, these roofs often last 25-40 years. The difference comes down to ongoing maintenance and correct installation