A flat green roof. Which is much worse than just a flat roof. The drainage will clog and they’ll risk having a leaky roof every spring. And you can’t get up

A flat green roof. Which is much worse than just a flat roof. The drainage will clog and they’ll risk having a leaky roof every spring. And you can’t get up there with a snow shovel because it’s a green roof and you’d scrape off all the dirt and plants.