Green Roofs 101

What is a Green Roof?
A green roof is a vegetated roof that generally consists of plants, growing medium and a number of geo-textiles placed on top of a waterproof membrane. Ecoroof is another name for a vegetated roof but ecoroof generally refers to lightweight systems that focus on ecological benefits such as storm-water management. The modern green roof buildup has been around since the 1960’s when the technology began coming out of Germany.

Types of Green Roofs
There are two types of green roofs: Extensive and Intensive. Semi-Intensive green roofs are roofs that incorporate elements of both Extensive and Intensive green roofs.

Extensive Green Roofs: Extensive green roofs are generally low maintenance as they have a shallow buildup of 6” of growing medium or less. Extensive green roofs are often referred to as ecoroofs as they generally require limited watering and help retain water for storm-water runoff. These roofs generally have lower capitol costs to install and are more feasible due their lower weight of 5lbs (moss roof) to 40lbs (supports some grasses). Most extensive green roofs have around 4” of growing medium, are planted with succulent plants, and weigh 20-28 lbs/sf. Most extensive green roofs vary in cost from $10 to $25 sf depending on size and complexity.

Intensive Green Roofs: Intensive green roofs are generally installed to create open space, grow food or achieve other landscaping goals found at grade. Intensive green roofs require more maintenance, regular watering and can be considerably more to install due to the additional materials and structural needs. Intensive Green Roofs start around 8” of growing medium and weigh 50+ lbs/sf. Intensive green roofs offer a much larger variety of planting options.