Structural Requirements
结构要求
Green roofs add weight, or dead load, to the roof of a structure that must be factored into its design. Besides the weight of the roof membrane and roof insulation, the weight of the living roof components, growing media (soil), and plants must be taken into consideration. The weight of the components is typically expressed as a saturated weight or wet weight.
绿色屋顶会增加建筑物屋顶重量或净载重，这点在设计时必须加以考虑。除屋顶防水层和保温层的重量外，还要考虑生态屋顶构件、栽培媒介（土壤）和植物重量。构件重量一般用饱和重量或湿重表示。
Some extensive green roofs can weigh little more than a traditional roof with ballast; however, this weight can increase substantially as the thickness of the soil is increased to accommodate the wider variety of plants that can be placed in an intensive green roof.
相比带有压载物的传统屋顶，某些大型绿色屋顶重量多不了多少。但是，随着大型屋顶上可栽培品种的增加及相应土壤的加厚，屋顶重量亦会随之大幅增加。
The soil for a green roof typically weighs between 5.0 to 7.0 pounds per square foot per inch of depth (wet or saturated weight), so on a typical extensive green roof, a 3 inch depth of soil would add 15.0 to 21.0 pounds per square foot. This spread in weight is largely dependent on the composition of the soil and can vary between green roof providers. You should typically plan for an additional 3 – 5 pounds per square foot of load for the remaining components in a complete assembly.
绿色屋顶上1平方英尺大小1英寸深的土壤重量一般在5.0至7.0磅之间（湿重或饱和重量），所以1 ft* 1 ft* 3 in的土壤就会带来15.0到21.0磅的增重。所铺土层的重量大部分取决于土壤成分，并可能因绿色屋顶供应商而异。考虑到完整装配中的剩余组件，你一般应该为其预留出3-5磅的荷载重量。
（第一句中"that must be factored into its design”我不是很懂。有些地方可能不符合专业表达，楼主可相应修改。）