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

https://blogfreely.net/rothesqlmw/why-does-the-cheapest-flat-roof-quote-often-fail-early

Single ply roof guarantees usually cover 15-20 years, but these membranes can often last 25-40 years in real life. The difference comes down to factors like installation quality, maintenance, and weather wear