DensDeck® StormX® Prime Roof Board provides a higher level of performance and is recommended for mechanically fastened, adhered and partially adhered roofing systems. DensDeck® StormX® Prime Roof Board is FM classified for Very Severe Hail (VSH) in approved single ply membrane assemblies. This gypsum cover board was the first of its kind to pass FM VSH in a single ply assembly, when using an adhered standard 60 mil TPO bareback membrane. DensDeck® Storm® Prime Roof Board is approved in more single ply VSH systems than all other cover boards combined and is included in thousands of approved systems that can be found in FM RoofNav.