As for the time period of that sketch, being of medieval based building/origin I suspect, that would actaully have been a wooden shingle roof as oposed to stone, simply due to the technical and engineering skills needed to build such a structure (i.e stone at an angle). A feat that would have been difficult in that time period.
AS the imperial architecture is similar of design, then a WOODEN roof* in a fortification would not be a farfetched idea. Plus it breaks up the imperial stone texture which seems to "bleed" into one, adding depth.
Secondly rounded sixy roofs have just been pimped up a notch thanks to this mod. Now they are extremly sixy with their procative layering of texture depth and contrast. Give me those rounded roofs any day!
*Wooden forts are used all through out history as well as wooden roof's in stone buildings.
P.S THIS is from someone with great information AND a primary qualification into ancient stratigeic, military, and historical architecture.
P.P.S Sorry, but your comment was a bit rude and in no way constructive. As an "esteemed" texturer why dont you go away and do a better job to make the op's small release even more insignificant so you can feel much better?