Below is a compilation of most commonly asked questions and information we discuss with new clients. 

Apex Green Roofs Inc. is a design/build firm with more than 8 years of professional experience in a burgeoning green roof industry. We provide professional expertise and service throughout all phases of green roof implementation for both commercial and residential properties.

Please call or email us for more information.

T: 617-629-2739 | E: info@apexgreenroofs.com

What are the first steps in starting the process of having a green roof installed on my building?

EXISTING COMMERCIAL and RESIDENTIAL BUILDINGS: Knowing the total dead load, pitch, and waterproofing membrane of an existing roof structure is key for Apex Green Roofs to determine the best options for design and build-up of a green roof system. Once you are able to specify these key variables – you can begin the discussion of green roof system, installation cost and overall benefits.

DEAD LOAD CAPACITY: Determine how much weight the existing roof can support. This information can usually be found in architectural drawings or blue prints or hire a structural engineer to assist you. We can sometimes recommend a reputable structural engineer depending on the building location.

As a general rule of thumb, our lightest and thinnest green roof system weighs 15lbs per sf saturated weight with a minimum 2.5" soil depth. Therefore, your roof must be able to support at least this much weight.

PITCH: If the roof surface is not flat, determine the exact pitch. This information can usually be found in architectural drawings or blue prints or hire a structural engineer to assist you. We can sometimes recommend a reputable structural engineer depending on the building location.

WATERPROOFING: Can the waterproofing system that exists on the roof support a green roof system? If you are not sure what type of waterproofing system you have, it is likely that we can assist you in determining this.

NEW CONSTRUCTION COMMERCIAL and RESIDENTIAL BUILDINGS: If a green roof is part of a new construction project - Apex Green Roofs can work from the blueprints/architectural drawings to determine the best vegetated roof installation system based on the roof plan.

Apex Green Roofs Inc. is a design/build green roof installation firm – well versed in the design phase of construction projects. Our experience can be of great benefit when included earlier in the design process: helping to avoid flaws that impede green roof success.

What are the structural requirements of my building in order to have a green roof installed successfully?

As a general rule of thumb, our lightest and thinnest green roof system weighs 15lbs per sf saturated weight with a minimum 2.5" soil depth. Therefore, your roof must be able to support at least this much weight.

How much does a green roof cost?

Depending on the conditions of the roof, the total surface area, and the type of green roof system to be installed:

Extensive system can range from $8-$15 per square foot

Semi-intensive system can range from $15-$25 per square foot

Intensive system can cost $25+ depending on the ultimate depth of the installation, plant varieties, aesthetic goals, etc

What is my return on investment in a green roof?

While the installation of a green roof requires a larger initial investment up front than a typical non-vegetated roof, a green roof will last 3-4 times longer than a typical roof (an estimated 60-80 years). This is because the vegetation protects the surface of the roof membrane from exposure to UV rays and weather conditions (primarily rain and ice). Sun and rain break down the surface of the roof much more rapidly when the surface is exposed.

In addition, green roofs can reduce your heating and cooling energy costs - sometimes 50% or more. The best energy savings tend to occur on the largest buildings, but even small residential buildings will see some energy savings. Check out this Green Roof Energy Calculator developed by Portland State University, University of Toronto, Green Roofs for Healthy Cities and funded by US Green Building Council

In some cities and towns, grants and subsidies exist which can help fund the installation of a green roof. Tax incentives for installing a green roof exist in some parts of the country as well. Incentives are most prevalent in the area of storm water management; green roofs can absorb between 20% and 100% of precipitation in summer therefore reducing strain on waste water drainage systems and pollution caused by storm water runoff into streams, rivers and harbors.

Check with your local government to see if this is an option for you. Learn more about current green roof incentives available from municipal, state, regional and/or federal agencies on the

GREEN ROOF INCENTIVE RESOURCE: The American Institute of Architects (AIA) website provides one of the better summaries of available green roof incentives in their downloadable publication State and Local Green Building Incentives.

Do I need irrigation on my green roof?

NO: if implementing an extensive green roof system that is a functional solution for environmental challenges like storm water management, reduction of heat island effect, and preserving the life of the roof membrane. An extensive green roof system utilizes hardy sedum species (or stone crop plants) which are re native to coastal, alpine, and desert climates - therefore better suited to changing and harsh weather conditions found on roof tops.

YES: if implementing a semi-intensive or an intensive green roof system deep enough to support herbaceous plant varieties. These systems, often called roof gardens, may require periodic irrigation - dependent on the plant material. We can provide irrigation installation if required.

Are native or non-native species grown on a green roof?

This is why sedum species are the most commonly used. They are hardy ground covering plants tenacious enough to withstand whipping high winds, lack of rainfall and constant sun exposure. View our green roof plant list.

Herbaceous native plants tend to require irrigation to survive. In some installations, native species can thrive if given the correct conditions and proper care.

Learn more about green roof plants from research performed at the Chicago Botanical Garden conducted by Richard Hawke

Can a pitched roof support a green roof system?

Yes - the maximum pitch for a roof without the use of slope retention materials is 2:12.

A green roof can be installed on almost any roof pitch. Installation costs directly increase with the pitch of the roof simply because more materials are needed to support the vegetation, and these roofs may require more initial maintenance while the plants establish themselves.

What happens if I have a leak on my roof?

EFVM (Electric Field Vector Mapping) testing is one method of testing we use in order to find the source of the leak quickly and efficiently.

In this method of leak detection, an electric current triangulates where the leak is to within a foot of the source of the leak. As part of your warranty with Apex Green Roofs, if you have a leak, we will conduct EFVM testing in order to find the source and we will then patch your roof membrane and repair any damage to the living roof system that may have occurred due to the required repair work.

Some roof systems are not EFVM compatible, and therefore require a more manual leak detection process. Therefore, warranties for non-EFVM compatible roofs can be slightly more expensive than those which are EFVM compatible.

What type of waterproofing should I have on my roof surface before installing a green roof system?

We recommend waterproofing systems that are compatible with EFVM (Electric Field Vector Mapping) testing, including TPO, PVC, and liquid plastics.

Some roof systems like EPDM, are not compatible with Electric Field Vector Mapping, and asphalt can be easily eaten away by plant roots.

A green roof system can still be installed on non-EFVM compatible roofs, however, certain precautions may need to be taken to either add a protective surface (root barrier) to the roof membrane before installation, or the overall warranty cost may need to be increased to cover the manual leak detection process on non-EFVM compatible roofs.

What kind of warranty plan does your company provide?

Apex Green Roofs offers a full 10 year warranty on plant materials and green roof components. Should a leak exists at any point, we will help source and repair the leak using EFVM (Electric Field Vector Mapping).

Roofs that are not EFVM compatible can still be covered by warranty, however, this warranty may cost more due to the manual leak detection process certain roofs may require.

In addition, we include 2 years of maintenance with all of our contracts. While a green roof is generally very low maintenance, it is important to check that the plants are establishing themselves well, and much of this process occurs within the first two years.

How does legislation incentivize a green roof for a homeowner, developer or building owner?

The current trend now shows municipalities are the most pro-active in creating green roof incentives. Especially areas close to water sources because the reduction of stormwater runoff is the main motivator for green roof incentives.

If you are interested in local incentives for green roofs call your local Bureau of Environmental Services as a starting point. Municipal, state and federal legislation promote vegetated roofs through these types of incentives:

TAX INCENTIVES: Tax credits or abatements can be applied to a tax bill based on a specific dollar amount per square foot of vegetated roof space.

DENSITY AND ZONING BONUS: Municipalities are granting additional space allowances to developers and owners who implement design solutions that lessen the negative environmental impact of an occupancy.

FAST TRACKED PERMITTING: Streamlining the permitting process for building, plan and site permits for developers. This type of incentive is mainly based on LEED Certification.

GRANT PROGRAMS: These programs help reduce the upfront cost of installing a green roof.

LOANS: Zero to low-interest loans are available in some locations to install green roofs on residential, commercial and industrial buildings.

GREEN BUILDING RATINGS: Administered by the U.S. Green Building Council (USGBC), Leadership in Energy and Environmental Design or LEED Certification is required or awarded by many U.S. federal agencies, state and local governments. A green roof installation can earn up to 19 LEED points.

Green Roof Technology L.L.C., based in Baltimore MD, feature a succinct break down on Green Roofs and LEED Certification point earning potential.

GREEN ROOF INCENTIVE RESOURCE: The American Institute of Architects (AIA) website provides one of the better summaries of available green roof incentives in their downloadable publication State and Local Green Building Incentives.