Green roofs have long been popular in mainland Europe, but now they’ve become a growing trend in the Americas as well. You may have heard about these “living roofs,” but how do they even work?What benefits do they have for your business? We’ll break down these questions and more in today’s discussion!
What are Green Roofs Used For?
Businesses and property developers alike favor green roofs for their beauty and energy-saving capabilities. For simple building designs, shallower extensive designs are typically preferred. For larger buildings and homes, building engineers may instead choose an intensive design. Also known as rooftop gardens, intensive designs provide excellent getaways for weary employees looking for some fresh air.
Speaking of fresh air, green roofs have several environmental benefits that often make them appealing to local governments. Some states even offer tax incentives for companies that adopt green roofing practices. If you enjoy great air quality, and you’re looking for your next flat roofing replacement, this could be a great opportunity for your business.
What are the Advantages of a Green Roof?
There are plenty of perks to installing a green roof on top of your office building or store. For instance…
Green Roof Benefits
- The cooling factor decreases energy costs.
- Plants and growing medium absorb a high percentage of moisture, decreasing runoff.
- Multiple layers prevent damage to the underlay during hail storms.
- Plants naturally improve air quality.
- Lush plant life and enchanting wildlife.
- A moderate lifespan of up to 50 years.
A green roof and technology for interior energy efficiency go hand in hand to produce some incredibly cost-effective engineering. Is it practical for every business? No. But many can and will benefit from green roofing as it becomes increasingly affordable.
How to Make a Green Roof
While the total number of layers in a green roof vary between companies, most feature five distinct segments. On top of the underlying roof, builders start with a waterproof membrane. Next comes a durable root barrier that prevents the budding plants above from growing downward. In the middle of the living roof is the drainage layer, which allows any leftover moisture to escape to the pre-made drains. On top of the drainage layer is a special filter cloth, which holds our final layer. At the summit of our living roof is a mixture of growing medium and plant life.
Layer Summary (Top to Bottom)
- Plants and Growth Medium
- Filter Cloth
- Drainage Layer
- Durable Root Barrier
- Protective, Waterproof Membrane
In addition to these segments, a series of drains will need to be constructed to allow any leftover runoff water to escape. This prevents plant rot and other unwanted plant diseases.
Green Roof Vs Traditional Roof
There is a world of difference between green roofs and traditional commercial systems. Most commercial structures utilize a single ply membrane or another flat roofing design. These incorporate a few protective layers, carefully bound together by adhesives and heat bonding. Green roof systems however, are usually constructed on top of an existing roofing system. That underlying layer must be reinforced to withstand the added wait of growth medium, plants, and all the additional layers.
Green roofs also behave differently in the way they handle light and heat from the sun. Traditional roofs utilize reflective colors and coatings to bounce light away from the rooftop. Living roofs, on the other hand, use a natural process called evapotranspiration. Basically, plants gently release water from their leaves which is evaporated by the sun. This cools the air and soil, while the plants happily absorb the sunlight as part of their continued growth cycle.
How Long Does a Green Roof Last?
One of the major differences between typical commercial roofing and living roofs is system lifetime. While a well-made, premium membrane could last between 25 and 30 years, the 50 year maximum lifetime of green roofing is much more impressive. The initial installation costs may be greater, but this is offset by energy savings and the longer lifetime.
Can You Walk on a Green Roof?
Yes, but you may want to avoid doing it too often if you have an extensive roof. Semi-annual maintenance requirements mean that you rarely have a reason to be on the roof in the first place. For larger semi-intensive or intensive systems, walking is not a problem. Just be careful not to step on the plants if you ever have to water them!
Are Green Roofs Cost Effective?
A typical EPDM membrane roofing system will cost between $4 – $8 per square foot, while the average cost of TPO or PVC may go as high as $8.50. The base cost of a green roof starts at $10 per square foot. Intensive designs start even higher at $25 per square foot. One also has to factor in any additional roof supports that will be required to sustain the living roof’s weight.
So there’s clearly a disadvantage in terms of starting costs. However, we have to keep in mind the savings benefits of green roofs are played out over a long lifetime (up to 50 years). Consider also the extensive energy savings to be relished during that period. Ultimately, green roofing systems (especially extensive designs) are very cost-competitive against traditional commercial systems.
Get an Estimate for Your Green Roof!
Our team at Andrew's Roofing would be happy to talk with you about your upcoming roofing project! Give us a call today at 561-688-1066 and get your estimate for a green roof or another energy-efficient design.