We say sometimes the growing green roof opportunities are like navigating the wild-wild west. Unclear rules, possible high risk, and unsure if the Sheriff is a good or bad guy.
Green roofs are a place in the landscape that are touched by many trades in the sequence of construction and maintenance. They are also new to many of those trades. Best practices of how the trades and building functions intersect are not yet figure out. Each one we work on ends up having a different types of material and critical path for installation. A well-coordinated design and installation of greenroofs that satisfies everyone is possible, but only if everyone involved collaborates well on installation and risk mitigation strategies for each stakeholder.
Our favorite experiences are when a general contractor, roofer, supplier of materials, architect, landscape architect, and engineer can meet together during the design and budget stage of a project, and without egos in the way identify the best strategy to build the project. This allows the water proofing warranty, structural capacity, aesthetics, plant health, soil profiles, drainage, stormwater and irrigation management, and maintenance considerations to all be figured out together in a way that makes all parties happy. It gets everyone on the same page with a plan that can be executed in the field with smooth coordination and multi-stakeholder teamwork.
As exciting as the wild-wild west might be, we prefer a bit more civility, coordinated effort, and understanding among folks.