Already a popular trend in Europe, vegetated green roofs are becoming increasingly popular throughout the United States. They are being installed on office buildings, skyscrapers, large manufacturing plants, and even residential homes in cities and towns across the country. Green roofs are most common in dense, urban settings where there is not much room for vegetation to grow at ground level. There are two different types of green roof systems: extensive and intensive.

Extensive Green Roof Systems

Extensive systems are simpler and lighter weight than intensive systems. These systems range in thickness from 2-6\’94, and weigh approximately 15-30lbs per sq ft. Due to their light weight and low profile, they require less structural support and can be used on roofs with a slope of 30\’b0 and higher. They generally consist of tough, hardy succulent plants that are tolerant of the extreme heat, wind exposure, and temperature fluctuations on roof tops. Sedums are most commonly used in extensive systems because they are low maintenance and drought resistant, meaning they require minimal nutrients and irrigation. They are shallow, rooting self-generating plants which spread rapidly to quickly create a dense, vegetative cover with minimal soil. Typically extensive systems are grown in modular trays that make installation fast and simple.

Although these simple systems are a cost-effective, low maintenance alternative roof, there are some disadvantages when compared to intensive roofs. There are much less design capabilities available for extensive green roofs as there are a limited variety of plants, such as alpines, succulents, herbs, and some grasses, that are suitable for use in these modular trays. These systems also generally do not permit rooftop access and recreation.

Intensive Green Roof Systems

Intensive systems are high profile, rooftop gardens and parks. They range in thickness from 6-15\’94+, and weigh approximately 50lbs+ per square foot. These intensive systems are most applicable on flat, level roofs which are structurally engineered to hold their tremendous weight. A limitless variety of plants, including large trees, shrubs, and perennials can be incorporated into the rooftop planting design. This style is more permissible for human access and recreation, and therefore includes walkways, terraces, and other structural features to make it an enticing public space to spend time. However this style of planting will most likely require irrigation and maintenance as opposed to the extensive systems which are minimal care. As these rooftop gardens are much more elaborate, they also tend to be more expensive to install in comparison to the extensive system.

There are many challenges when planting green roofs as these projects require a lot of coordination and planning to ensure that everyone stays safe and installations run smoothly. All of the equipment and material necessary to complete the job must be approved to meet weight restrictions on the roof top. Logistics also play a large role as cranes for lifting equipment and materials along with scheduling with other contractors.

Green Roof Contractors

All Seasons Landscaping has the experience coordinating with crane operators and roofing contractors, finding the right, lightweight equipment to do the job, and thoroughly planning and scheduling all aspects of green roof installations.  If you have any questions bidding your next green roof project, please contact All Seasons Landscaping Contractors.