The insulation is under the membrane. This is bad. The insulation can collapse and loose support for the membrane. The membrane can tear and leak. The reason for this bad design choice is often a preoccupation with the "greenness" of the blowing agent of the rigid insulation. Successful green roofs have historically used extruded polystyrene (XPS). XPS can get wet and still perform. The blowing agent of XPS is arguably not the "greenest of the green." Uproven "green" blowing agents used with polyisocyanurate insulation seem attractive at first blush, but insulation assemblies need to be protected from water and hence the location under the membrane and the structural loading of the overbuild assembly needs to be taken into account.