I like to use mats in these applications because they can be attached at the top of the roof and provide excellent vertical shear resilience and tensile strength, depending upon the material and application.
We've used this design successfully and although the root barrier/liner says 'optional', I'd recommend its use. Having said that, if your application is a backyard shed or similar and you are on a budget, the liner may be optional, depending on the type of metal roof you are using.
This design has its basis in the sloped mat design tested at the UF Hurricane Simulator.
If you'd like a larger .pdf or .dwg file email me.
Happy Green Roofing!
|Green Roof Typical, Sloped Standing Seam Application|