What are the Benefits of Green Roofing?

view from above of a green rooftop on a building

New Orleans is a historical city, and well known for the partying that takes place, especially during Mardi Gras. What people that don’t live here realize though, the businesses and residents here are very environmentally concerned, which is why more commercial structures are considering the green roofing option.

Is green roofing just solar panels, if not, what is green roofing then? Is that just referring to the color? No, green roofing may be in combination with solar panels, but solar panels alone are not what makes green roofing. And it is so much more than just painting the rooftop green! 

Can you install green roofing on a commercial building?

Absolutely! In fact, they are the primary place for green roofing to be installed. While a residential structure with a flat roof can have green roofing, and the residents of the building could benefit from the plant life it supports. 

Primarily, green roofing has been installed on commercial structures here in the United States. In Europe, green roofing has been practiced for decades, even longer. Here, they are used to create a garden for retreating and visitors, or a park, even limited farming can be accomplished with green roofing. 

What are the benefits of green roofing?

A green roofing system can be expensive to install, engineering inspection is required and continuous maintenance, but the ROI is ongoing! A few benefits you can expect from a gree roofing installation include: 

  • Economic: An increased R–value is the first thing you’ll notice from green roofing, ideal in areas where the summers are hot and humid like New Orleans. With the building being cooler, the HVAC works less, so you’re saving money on utilities and get a longer lifespan from the HVAC system. Where the traditional commercial roofing has to be replaced or reroofed every 10 to 15 years, green roofing will give you over 40 years of useful life, saving you over $200,000 during that 40 years. 
  • Stormwater Management: Green roofing is ideal for controlling stormwater retention and runoff in cities and urban areas where there is a shrinking about of green space and increasing impervious surfaces. Instead of precipitation running off a roof into gutters and flowing into the sewer system, with all the contaminants and dirt from the air and the roof, green roofing will retain the water for the plants. It is creating a contained ecosystem and growing medium, reducing the stormwater filling the sewer system and nearby lakes and rivers. 
  • Urban Heat Island Effect and Improved Air Quality: It is common knowledge that cities are warmer than rural areas, especially in the New Orleans summertime. This is referred to urban heat island effect that takes place where there is more paved surfaces that are absorbing the solar radiation the radiating it back out as heat. This increases the air temperature by as much as eight degrees. Green roofing also clears the air as the plants generate clean air and make it less humid, a win-win for anyone with respiratory issues. 
  • Natural Insulation: Green roofing removes the dark, heat-absorbing surface that is typical of commercial structures, and provides a layer of natural insulation, reducing the need for thermal insulation. It also dampens the noise factor, a common complaint in the city.  
  • Greenhouse Gas Emissions Reduced: With green roofing reducing the need for the HVAC to run more, this reduces the greenhouse gas emissions too. This not only reduces the footprint but reduces the need for more fossil fuel combustion while it increases clean oxygen production.
  • Urban Amenities: With green roofing, the occupants and visitors to a commercial structure will have access to more natural, an oddity in the city today. Green roofing with fruits, herbs, and vegetables will make for an aesthetically pleasing environment for guests, meetings, or recreation. Endangered birds and insects, like the honeybee, can make a home in this natural habitat that green roofing provides. 

How are green roofs installed?

And how long does it take to install a green roof? How green roofing is installed will depend on the one you choose.  Most of the time, it can be accomplished within a week to ten days. The three most common choices for commercial structure green roofing are: 

  • Intensive: The most common type of green roofing that can be gardened, walked on, and even used for entertainment.
  • Semi-intensive: A bit shallower than the above-described intensive green roofing, between six and ten inches. They can support certain bushes and grasses and is versatile except they are not suitable for tall shrubs or trees or walking on. 
  • Extensive: This is the shallowest of green roofing, under six inches, thus it can’t support anything with an in-depth root system. Ideal growth for moss or sedums makes this more popular for residential structures.

There are a few different components to install green roofing, with the following layers:   

  • Waterproof roof deck
  • Root barrier
  • Drainage Membrane  
  • Filter layer 
  • Green Roof Substrate and growing medium
  • Vegetation

Does a green roof still require guttering?

Green roofing doesn’t need guttering as much as it needs ample, proper drainage. Which a flat roof would need anyway, but with green roofing, it becomes more important.  The drainage layer for green roofing is essential because it will need to handle large volumes of water yet supply a sufficient amount to the gardening. 

HDPE membrane is used for the drainage layer on most green roofing. It has cavities that collect water, retaining it for the vegetation, which draws it as needed. When there is an excessive amount of water, like after a heavy rain, it passes through perforations and travels to a drainage space installed below where safely disperses. 

How often does a green roof need maintenance?

Once a green roofing’s vegetation is established, it will need weeding two to three times a year, preferably before the weeds seed and make more weeds. It will also need fertilizing periodically, you can find several online instructional videos for the frequency and what type of fertilizer.

Are there any drawbacks to installing a green roof?

We’ve already mentioned the upfront expense of green roofing, but the investment comes back as ROI with the decreased utilities and the increased lifespan of the roof. Like anything though, there are drawbacks to green roofing too: 

  • Risk of Leaking: Even with a root barrier, if green roofing isn’t inspected on regular basis, there can be that one errant root that gets through and into the roof decking. 
  • Structure Limitation: An engineering inspection is recommended before installing green roofing. Not all structures are able to handle the extra weight of green roofing. 
  • Selective Planting: Depending on if you choose extensive or intensive green roofing will determine what plants you can have on your green roofing.

Taking It Home – Can you install green roofing on your home?

While green roofing is commonly installed on flat roofing and most homes have sloped roofing, it is still possible to have green roofing at home.  It is recommended not to have more than 3 feet for every 12 feet slope. If you have any higher slope, you’ll need the roofing reinforced. 

a rooftop garden in a big city
Related Articles

Table of Contents

  • We’ll Keep Your Details Private. Request Your Quote Worry-Free.