Intensive green roofs are commonly used on commercial buildings where owners desire large green areas that incorporate all sizes and types of plants. These roofs will have grasses, ground covers, flowers, shrubs and even trees. They will often include paths and walkways that travel between different architectural features to provide space where people can interact with the natural surroundings. Benches, tables, planter boxes, greenhouses, ponds and fountains offer people places to relax, dine or work in park-like settings.
Extensive roofs are more often used for single family and multi-family residential buildings. They are also best suited to spaces where people are seldom going to be walking on the roof surface. People walk on them mainly for maintenance. These green roofs also fit outbuildings like sheds and garages very well. Other names include “low profile” and “performance.” The design is supposed to give high performance to water use and thermal advantages, while keeping the overall weight of the roof low.
Extensive green roofs are the simplest to install and are very often added to existing roofs. Depending on the source you look at these roofs may add 10 to 35 pounds per square foot to a roof’s load.