Green Roof Construction-Structural Considerations

October 7, 2010 at 1:40 pm

Structural Support of the Green Roof

Excerpts from  Green Roof Construction and Maintenance,  by Kelly Luckett, 2009, published by McGraw-Hill’s GreenSource Books

Hi Green Roof Fans,

As one of the contributing editors here on – you may know me as “The Green Roof Guy” – I’m starting a series of excerpts from my book Green Roof Construction and Maintenance:

Rooftop Garden – Public Access
Having determined that the rooftop garden will be the place for people to gather and having provided access, one must ensure that the roof structure has the necessary structural capacity to support rooftop activity. Building codes may vary, so it is important to determine the local requirement for live loads and dead loads, and to understand how the green roof being built relates to weight requirement. The entire green roof assembly, including plants and the water required to saturate the growth media, is considered part of the dead load of the structure. Water in excess of that which saturates the growth media, snow and people visiting the green roof are all considered part of the live load of the structure. One must formulate a preliminary idea of what type of plants are desired and the proper growth media depth required to support them.

Saturated weight data should be available from the manufacturers of the intended green roof components. Typical rooftop gardens incorporate varying growth media depths and planters to support various plant choices. This will require calculations of the point loading of these various plant choices. Evaluating loading requirements and upgrading the structure to support  the green roof is easiest and most economical in the design phase of the construction of the building. Evaluating the structural capacity and making upgrades to an existing structure is significantly more difficult and more expensive. Many retrofit green roof plans die at this stage due to inadequate structural capacity and the prohibitive cost of upgrades. While there are some creative strategies of employing irrigation systems to reduce growth media depths in order to reduce dead loading, live load requirements could mean abandoning public accessibility to the rooftop garden and opting to design a simpler, extensive roof.

Green roof – No public access
When the green roof will not be a public gathering space, the live load structural requirements for the green roof are less complicated. Once the load requirements of the local building code have been determined, one must calculate the saturated weight of the green roof system to determine if structural upgrades will be necessary. Again, this is going to require some idea of the type of plants intended to grow on the green roof and the growth media depth required to support them. Typically the entire green roof will have a uniform dead load based on the saturated weight of the green roof assembly, though one may considering positioning planters or mounded growth media over structural support members to incorporate some strategically located deeper growth media for larger showcase plants. The plant palette is significantly expanded by increasing the growth media depth. As increased depth results in increased weight, there are often trade offs that balance structural cost with plant selection. Once the dead load of the green roof has been determined, a new structure can be designed with the required capacity. For an existing structure, one must begin by determining the structural capacity and design within those parameters. Irrigation systems have been successfully used to reduce growth media depth, and thus weight of the green roof system, for projects that would have otherwise required costly structural upgrades. For example, the green roof on the Ford Rouge Dearborn Truck Plant thrives in less than 3 inches of growth media and is sustained during periods of drought by the strategic use of supplemental irrigation.

Make sure to read my column, and to learn more about my company,  visit my website at:  or send me an email to:

Kelly Luckett, A/K/A The Green Roof Guy

LEED Credits and Green Roof Construction

October 7, 2010 at 1:38 pm

Excerpts from  Green Roof Construction and Maintenance,  by Kelly Luckett, 2009, published by Mcgraw-Hill’s GreenSource Books

Hi Green Roof Fans,

As one of the contributing editors here on – you may know me as “The Green Roof Guy” – I’m starting a series of excerpts from my book Green Roof Construction and Maintenance:

The United States Green Building Council (USGBC) has developed a rating system that awards designers and property owners with various levels of environmentally responsible building strategies.

The 69-point rating system is broken into five categories: Sustainable Sites (SS), Water Efficiency (WE), Energy and Atmosphere (EA), Materials and Resources (MR), and Indoor Environmental Quality (IE). There are five additional credits available for Innovative Design (ID). By taking prescriptive steps, the project team captures credits in the various categories to reach one of four levels of achievement: Certified, Silver, Gold, and Platinum.

For information on possible LEED credits associated with the use of specific green roof systems or components, contact the manufacturer.   If you’re using one of my Green Roof Blocks  products, contact me by  email.  For more information on the USGBC or LEED, visit the USGBC website at

The list of credits below can apply to construction of green roofs.

LEED Green Roof Possible Credits

SS 5.1
SS 6.1
WE 1.1 and 1.2
EA 1.1 to 1.10
MR 4.1 and 4.2
MR 5.1 and 5.2
ID 1.1 to 1.4

The full list is available on Page 142 of  Green Roof Construction and Maintenance  at

Make sure to read my column, and to learn more about my company,  visit my website at:  or send me an email to:

Kelly Luckett, A/K/A The Green Roof Guy

Calculators for Green Roof Construction

October 7, 2010 at 1:36 pm

Two Valuable Calculators Available for Planning:

Water Runoff Calculator and Green Roof Blocks Materials Estimator

Excerpts from  Green Roof Construction and Maintenance,  by Kelly Luckett, 2009, published by McGraw-Hill’s GreenSource Books

Hi Green Roof Fans,

As one of the contributing editors here on – you may know me as “The Green Roof Guy” – I’m starting a series of excerpts from my book Green Roof Construction and Maintenance.   As President of Green Roof Blocks, I’ve been involved in the industry since 1980, am a LEED Accredited Professional, and a Green Roof Professional (GRP).   Here we go:

Stormwater Runoff
Discussions of storm water runoff are typically concerned with the impervious surfaces within a certain development or a certain watershed.   Many municipal planning and zoning authorities have implemented policies restricting the amount of storm water runoff a new or existing development is allowed to generate. Some mandate no increase in the pre-development runoff volumes for new projects under consideration for building permits.

To help further promote green roof projects in the United States, we decided to make  our Water Runoff Calculator tool available free of charge.   The Excel based spreadsheet is available for download from the “Downloads and Calculators” page of the Green Roof Blocks website.

This storm water management tool quantifies storm water management values. Storm water runoff coefficients speak to the rate and volume at which water percolates into the ground rather than running over the ground’s surface. Where the surface of an undisturbed forest floor allows water to quickly be absorbed into the ground, a concrete or asphalt parking lot would instead repel water across the surface to lower neighboring grades. The difference in the permeability of the surface is sometimes referred to as imperviousness of the surface.

Green Roof Blocks Materials
Estimating materials well in advance of a project can be a challenge. Always contact the product providers for assistance and specifics. For example, we developed an easy tool to  help our clients using Green Roof Blocks and Green Paks- the Green Roof Materials Estimator, which is also  available at the “Downloads and Calculators” page of  our website. Assumptions in this Excel spreadsheet allow you to put in an advance date and receive an accurate estimate for your proposal based on that future time frame. Use this calculator to build multiple options based on your budget to present to your client. For questions, please contact us and we will be happy to customize a solution for your project.

Make sure to read my column, and to learn more about my company,  visit my website at:  or send me an email to:

Kelly Luckett, A/K/A The Green Roof Guy

The Brooklyn Grange Rooftop Farm Project

May 25, 2010 at 2:53 pm

What an awesome concept the Brooklyn Grange Rooftop Farm project is!  I first heard about this late last year but then about a week ago colleagues Bill Foley and Wendy Wark alerted me again, and so now I finally took action this afternoon by donating $50 to the cause.  Not a lot of money, but enough to show‘s support for an extremely worthwhile undertaking.

As we all know in this green industry of ours, underutilized rooftop space is one of the greatest real estate potentials for greenroof implementation.  In this age of trying to come together as a community, organic farming, and healthy food plus security issues, what better way to help mitigate the developmental woes of a building’s footprint that planting crops at rooftop level?  And (hopefully) make a profit?

That’s exactly what Brooklyn Grange is doing for their own community – they’re in the process of starting a rooftop farm with a team of five partners and a whole bunch of friends, and the organizer, Ben Flanner, says it’s “A big project that requires a lot of hard work to say the least, and one that sets an example for using under-utilized rooftop space across this dense city to do something productive.  There are many benefits to the city and community from such an operation.”  Most certainly, and we can all help by donating even just $1 – by this Friday, May 28, 2010 – but $10 gets a bee named after you!  Actually, for all donations of $10 or more, they will list you as a donor on their website and name one of their honeybees after you.

They’ve setup a campaign on an interesting new website called kickstarter, which is designed to help raise funds for enterprising people to start new projects – such as this one.  Kickstarter has a unique platform where you set your goal at the onset of the campaign, and then you need to hit that goal from online pledges to receive funding, otherwise all of your pledges are simply returned to the pledgers.  People can click on your project and pledge any amount during the course of the campaign.

So what is the project really all about?  Their page on kickstarter  says:

“Brooklyn Grange will be a 1 acre rooftop farm situated in New York City. Such a commercially-viable rooftop farm has yet to be realized in this country. We will use simple greenroof infrastructure to install over 1 million pounds of soil on the roof of an industrial building on which we will grow vegetables nine months of the year. Being in the country’s largest city, the farm will create a new system of providing local communities with access to fresh, seasonal produce. We plan to expand quickly in the first few years, covering multiple acres of New York City’s unused rooftops with vegetables. The business has many environmental and community benefits, and allows our city dwelling customers to know their farmer, learn where their food comes from, and become involved.”

Ironically, as it turns out, Brooklyn Grange’s first project isn’t in Brooklyn but on a 40,000 square foot, 6-story industrial rooftop in Queens!  And the group is very happy to have the good fortune  of this company’s backing, too, and they’ll be selling their produce in both boroughs as well, including tomatoes, eggplants, chilies, and various leafy greens.  The farm will be run by Ben Flanner, who started and ran a proof of concept rooftop farm in the summer of 2009.  The beyond-organic produce will be sold directly to the community at an onsite stand, affording shoppers a direct relationship with the farm and farmers.  Additional produce will be sold to a small group of market-driven local restaurants.  He explains the business philosophy:

“We are a for-profit business. We believe in adding fiscal sustainability to the sustainability rubric so that urban rooftop farms can expand across the city, the Northeast and even the world! Any profits we make will go towards paying our farmer a living wage and whatever remains will be reinvested in the business so we can keep growing.” ~ Ben Flanner

In what stage is the project now?  In a newsletter today, May 25, 2010, Ben shares that “At this moment, we’ve installed about two-thirds of the rooftop soil, and we have about 110 sacks (~300,000 lbs) to lift yet with the crane, continuing tomorrow morning early.”

Brooklyn Grange needed to hit their goal of $20,000 by Friday, May 28, to get some important funds for the farm through kickstarter, and I’m pleased to report they have!  As of right now, supporters and fans have pledged $20,740.50, but please consider contributing more to their entrepreneurial greening efforts.  To pledge now, visit here, and they’d love it if you would also help spread the word!  Read “High Above Queens, the Dirt Is Deep, and Good” by Diane Cardwell  in the New York Times of May 13, 2010, see their profile on kickstarter.

For more info, visit  Brooklyn Grange’s own website or contact Ben at: or 608.215.0218.

Happy veggie rooftop greening! ~ Linda V.