In this contribution, we will discuss the relationship between mean flow statistics, the topographical parameters of a rough surface, and the blanketing layer that forms over it. To this end, blanketing layers have been computed for a wide range of roughness conditions based on results from direct numerical simulations of turbulent channel flow and have been analysed using standard topographical approaches. The results demonstrate, e.g., that the previously observed linear relationship between 〖∆U〗^+ and the effective slope of the blanketing layer for barnacle roughness is also observed for other statistically isotropic rough surfaces, but that deviations occur for strongly anisotropic surfaces. The Reynolds number dependency of the blanketing layer topography will also be investigated for several representative surface conditions.