Quote from Squad26 minutes ago, Squad said: That's not right. $surfaceprop should be one of the properties in this list (not sure if this list can vary between different branches of Source).
You can make your own surfaceprop (in a mod at least, it doesn't work when packed in a map). Not only it varies between different branches, but also between different games and mods. It tells which sound to make when shot and stepped on, and also control the penetration value of surfaces in CS:GO. Also some other cool stuff like friction and jump height.
At any rate you shouldn't need to use something other than the usual wood/concrete/metal/dirt/plastic etc, which can be found everywhere.