Specifically for roofs, I'm curious how much more expensive and lasting a nature-roof is. For example, take a residential house. The roof needs to be able to su

Specifically for roofs, I'm curious how much more expensive and lasting a nature-roof is. For example, take a residential house. The roof needs to be able to sustain the weight of the soil and collected water. Roofs are typically built with slopes so that the water doesn't collect. Now you have to design the structure to support that. Drainage is an interesting problem too. How do you drain the water without losing your soil and soil nutrients? I think a solar roof is a better use of the roof, if installed properly.