Hello ,
I’ve been trying like a headless chicken, and thanks to Phiserman Phriend, I’ve been able to create custom fake brushes to block problematic roof locations on Dubrovnik. This script is based on Harlekin’s one, which already bocked some roofs because of SK.
The following areas are player-blocked, specs can still go through:
Tested and working 
Download:
If you have any more location to block, just tell me Hope some admins will enjoy it.
Mateos.
How about the truck in front of the bank and other stuff that you can shoot through. Is it possible to fix those?
What I have added is player block stuff, I dunno if I can add brushes with bullet-proof surface, will look. This is my first attempt at doing an ETPro script, so I just know fake brushes x)
Edit:
Will try to add to 65536 (PLAYERCLIP) the value 1 (SOLID) to have it bullet-proof, but for now I’m waypointing my map Will try so asap.
PlayerClip stops players but not specs and Solid blocks both, but you can still shoot through… If there were an arg WeaponClip maybe, there’s MissileClip but the models are blocked with this in the map, so it just block Panza and I guess Mortar.
The list of the args seems to say it’s not possible 
http://wolfwiki.anime.net/index.php/Map_scripting#Contents_Flags