Frequently Asked Questions


What is a green roof?

A green roof (also known as a vegetated roof, living roof, or ecoroof) is a layered system of components including vegetation on top of an existing roof deck. A green roof can either completely or partially cover a rooftop depending on the desired goals of the project.

What are the benefits of green roofs?

Green roofs provide a wide array of environmental and economic benefits. Green roofs absorb rainfall and reduce the flow of stormwater runoff, double or triple the life of rooftop waterproofing membranes, insulate buildings, sequester carbon from the air, mitigate urban heat islands, and create habitat for beneficial species such as honey bees. You can learn more about the many benefits of green roofs on our Benefits page. 


A green roof at the Ford truck plant in Dearborn, Mich., reduced the building's annual energy consumption by 7% (Earth Pledge, 2005).


What are the different types of green roofs?

The least expensive and lightest type of system, it uses < 6 in. of growing media. Sedum (a genus of drought-tolerant succulents) is the primary plant used in extensive green roofs because it can grow in just 1 in. of soil and weigh as little as 8 lbs. per square foot. After a temporary irrigation system is installed during plant establishment, extensive green roofs often require no irrigation.

This system blends characteristics of the extensive and intensive green roof categories. Semi-intensive systems are typically between 4–12 in. soil depth, and may contain a variety of vegetation ranging from sedum to grasses and shrubs.

This is the most sophisticated system, as it contains the largest amount of soil depth at 12–36+ in., and provides a wider variety of options for plant selection. The soil depth of an intensive green roof typically ranges from 12–36+ in. An intensive green roof is the most expensive, but also has the highest capability to mitigate stormwater runoff and insulate a building.

How much does a green roof weigh?

The weight of a green roof depends on the materials used and type of system installed. During the design phase, Recover always works with a structural engineer to determine a roof's structural loading capacity.

On average, an extensive green roof weighs between 10-30 lbs per square foot; a semi-intensive green roof weighs between 30-50 lbs per square foot; and an intensive green roof weighs between 50-300 lbs per square foot.

How much does a green roof cost?

The price of a green roof varies from project to project, depending largely on the following factors: green roof type, quality of the existing rooftop membrane, roof accessibility and fall protection, structural loading capacity, and ease of material conveyance to the roof.

Price ranges for design-build by system typically fall between:

  • Extensive: $10-50+ per square foot

  • Semi-Intensive: $25-200+ per square foot

  • Intensive: $20-200+ per square foot

What services does Recover Green Roofs provide?

Recover can work with clients through every stage of the design and construction process on any type of landscape-above-structure project. Our team of green roof professionals, builders, and designers is experienced at bringing projects from the design phase through material sourcing, delivery, conveyance, and installation. Additionally, we provide green roof maintenance and green roof remediation services.

Please visit our services page to learn more, or contact us at any time. 


Geographic Information System (GIS) studies have shown that real estate within 800 feet of green space increases in value by up to 22% (Nicholls, 2004).


What are the structural constraints of green roof construction?

There are three preliminary components to planning every green roof:

A watertight roof membrane is a necessary foundation for all green roofs. Ideally, a green roof is built on top of a new roof or one with a waterproof membrane that has been replaced within the past 5 years.

Recover always uses a structural engineer to assess the amount of weight a building can support during and after construction of a green roof.

Any occupied roof must have proper egress and railing systems in compliance with local regulations and current OSHA standards.

Can I grow vegetables on my roof?

Perhaps. Rooftop farms are of growing interest around the world, and it is important to address the challenges that come with the excitement. Rooftop farms are the heaviest systems we design, as vegetables require greater soil depth for healthy growth. Initial constraints include the structural loading capacity of the roof, waterproof membrane quality, and safety protection.

After working through some preliminary questions, Recover can assess whether a rooftop farm is right for your specific setting.

I’m interested in having a green roof. What is the first step?

Give us a call to speak with one of our project managers. Our office number is (617) 764-1310. Or, reach us by email at Once we’re able to gain a better sense of your site and the goals of the project you have in mind, we can move forward with a structural assessment and preliminary design.