Single ply roof guarantees usually last 15-20 years, but the roof itself can...

https://wiki-quicky.win/index.php/How_Long_Does_a_Single_Ply_Membrane_Roof_Last_in_Real_Life%3F

Single ply roof guarantees usually last 15-20 years, but the roof itself can serve 25-40 years if looked after properly. That difference comes down to regular care and spotting issues early