change the name of timber to building materials. Have these
found where
wood is at present and also in the mountains. Simple change and
no big deal
really
Until you build stone war machines... 
Actually, I have no problem with thinking of MEPBM fortifications
as being built almost entirely of wood. I just mentally move the
era from the middle ages back towards Roman times. Those guys
could sling up a fort in very quick order...
Gavin
Until you build stone war machines...
Oh yeah good point....not to mention stone ships! :o)
Consider this...the timber is just for the supports, drawbridges etc.
The stone is purchased "abstractly" by spending the gold. I dont
think Sauron is going to actually pay wages to orcs and slaves to
slap up a tower. The Free, well they are entirely too altruistic to
want to get paid as well! Therefore, no change to commodities!
As for the actual order, once again, taking the abstract view, the
sabo order represents maybe your agent paying off some goons to
unlock doors at the right time, or maybe someone found a hidden door
in the wall that was forgotten and can be used to invade the pop
center (It happened to Byzantium!) . Technically, the agent isnt
destroying the forti per se, but rather making it ineffective?
There is my two cents, please feel free to tear me apart!
Fletch