Summary

Green roofs are roofs covered with living plants and layered materials, a practice that dates back to ancient structures and later spread through Europe and North America. This guide explains how green roofs differ from rooftop gardens and describes three main types: extensive, semi-intensive, and intensive, based on soil depth, plant diversity, weight, cost, and access. It outlines common system layers like root barrier, drainage, filter fabric, and engineered growing media, plus modular options, and notes why media choice affects weight, drainage, and nutrient runoff.