This study in on an application and performance of copper plate as root barrier for green roof system evaluation. We suggest new materials which already used as roofing supply, as analyzing the performance of against the root penetration and corrosion, furthermore workability and suitability as root barrier for green roof foundation. It proved that the copper include chemical component to control a certain chemical component at growing point of plant. It is effective to control the penetrating vertical power of root by copper, and this is using principle that lead to take root horizontal in the soil by growing fine root instead of thicken root not grow any more. This is different with exist chemical root barrier treated weed-killer or insecticide, give more safety for growing plant.