One of the most common questions we get about green roofs is what happens in the event of a leak. The process is very straightforward: a portion of the green roof is removed, the leak is repaired, the green roof is replaced, fingers are not pointed.
Let’s get into more detail, but first we’ll start with the basics.
Green roofs do not cause leaks. Roofing membrane breaches cause leaks, which is the case whether or not a green roof is present. Green roofs can actually extend the life of properly installed membranes because the green roof is a thick protective layer that protects the roof from UV rays, mechanical damage, and the very damaging effects of extreme temperature fluctuations. Read more in section 2.10 of this GSA report.
The best way to prevent leaks under a green roof are 1) require a high-precision leak detection test before installation of the green roof, and 2) only allow installation by an experienced and reputable installer. Any experienced and reputable green roof installer should be skilled in understanding the simple things required to avoid membrane damage: protect the membrane as a first step, and exercise care with sharp tools. A high precision leak test, such as EFVM, will ensure you are starting with full membrane integrity. Follow these 2 simple rules, and you are on the path to success!
You should get an overburden warranty. Furbish includes an overburden warranty for EcoCline. This is very simple: we agree that once a leak is located, we will remove enough green roof to access the leak, then we put the green roof back and replant it. This service is performed at no charge, regardless of fault. If Furbish or our installer was at fault, we will pay for leak detection and leak repair. When comparing overburden warranties, it doesn’t matter if the warranty comes from the roofing manufacturer, green roof manufacturer, or installer; just make sure it is a “no charge, regardless of fault” warranty, and you are fully covered.
Leaks under green roofs are not common, and leak repair is not usually expensive. However, without a leak detection system, leak location can be very frustrating, time-consuming, and expensive. EFVM® is a great and inexpensive leak detection system that can pinpoint a leak to the millimeter, and it allows for easy re-testing following green roof installation. EFVM® can be used to test most existing membranes for retrofit green roof applications. Sometimes other options such as high-voltage testing might be applicable.
Over the course of Furbish’s 150 green roof projects (over 2 million square feet) since 2003, we have been called to remove and replace overburden a total of four (4) times. Most of the time we uncover the spot in the morning, the roofer fixes the leak, the membrane is re-tested, and we replace and re-plant the green roof within a few of hours. Finger-pointing is not on the agenda.
So rest easy. Don’t let overburden be a burden.
