If you have any experience with green roof systems—especially if it’s your responsibility to specify those systems—you know they are complicated. Green roof systems are complicated not only because of the plethora of components they contain; they are also complicated because of their incredible ability to protect and extend the life of a rooftop, saving you money. Why is this complicated? Because it means that before you specify a green roof system, it is essential that you make sure the underlying roofing system is up to the challenge. Is it going to outlast—or at least match the lifecycle of—the green roof? If not, you may be digging up that green roof before you know it.
So how can you make sure that your roofing system will perform, and your green roof will remain intact for its lifecycle and deliver cost savings? Fortunately, there are a few simple, practical ways you can ensure that the lifecycle of a roofing system doesn’t compromise the long-term performance, energy-efficiency, and environmental benefits of its green roof components.
A green roof can last between 20 and 40 years if not longer, when properly installed and maintained, which is why it is important to consider a number of design enhancements when specifying a roofing system that will feature a roof garden. We recommend the specification of the following design enhancements, all of which are included in a typical 20-year warranted roof system. If you’re specifying a roof garden, you need your roofing membrane to last at least 20 years if the roof garden is to remain intact with its performance uncompromised.
Thicker Roofing Membrane
Using a thicker EPDM, TPO or PVC membrane on your roof system can significantly enhance the durability, weatherability, and puncture-resistance of the rooftop for a minimal cost increase that is more than made up for in lifecycle performance. Choosing a 75-, 80-, 90- or 145-mil membrane, for example, can increase the lifecycle of your roofing system by as much as 33 per cent and will cost as little as four per cent more than a thinner, less durable membrane. Using a thicker membrane can also increase seam strength by up to 25 per cent and enhance the wind-uplift performance of the rooftop, further enhancing its durability and stability.