I wrote last week about root barrier options to protect the Eco Brooklyn show house roof from root intrusion and/or bacterial degradation, which could potentially lead to leaks. Since Eco Brooklyn focuses on green building, I laid out some of the characteristics associated with the most commonly used root barrier materials, including manufacturing byproducts, potentially harmful compounds associated with root barrier leachate, embodied energy, and recyclability. I identified HDPE as the best among the alternatives analyzed and mentioned that I would follow up with information on pricing and availability for potentially suitable materials. I’ve contacted sales representatives at Zinco, American Hydrotech, Tremco, and Carlisle, though I have not heard back from all of them.
From the research I’ve done, these barriers range from about $0.50/sq. ft. to $2.00/sq. ft. and are generally available via mailorder only, through company sales representatives.
One of the suitable root barrier alternatives I identified in my initial post was Tremco’s Root Barrier VR. It is made from 40-mil (1 mm) HDPE and, according to the representative I spoke with, works well with EPDM roofs. The material comes in 4′ x 100′ rolls and can be in Brooklyn in 2 business days. In addition, the gentleman that I spoke with works from Long Island and offered to travel to the job site with a green roof “expert” to consult on the roof and additional items, including PV, daylighting, LEED accreditation, etc.
Zinco produces two root barriers suitable for our use, as well. The WSF 40 is a 0.4 mm-thick HDPE sheet specifically designed for use in extensive green roof systems and comes in 1,000-sq. ft. rolls. The WSB 80 root barrier is FLL-certified, heavier-duty than the WSF 40, and is rhizome-resistant (though not resistant to bamboo). According to the rep., it is typically not used for extensive/perennial roofs and the seams must be hot air-welded. It is more expensive than the WSF 40 barrier and is available in roughly 430-sq. ft. rolls.