Most comms, even very good comms, don't build repair facilities unless someone bugs them too. I don't understand why though, repair facs are possibly the most cost effective building in the game, other then refineries. -You can repair, so those silly people who make tanks without being an engi don't waste them. And people who are engis can repair faster, wasting less time. -You can rearm, which shouldn't ever be a problem but somehow is because people don't always drop ammo boxes for tanks. -You can upgrade, so people that can keep tanks alive can upgrade and continue to be useful -More base is always better then less base. If the enemy kills it then they didn't kill an important building or expensive tank. -Two people can repair at a time on it, unless they push each other off or are stupid about it. Three people can fit sometimes, although I don't know if it will repair that many people at once... Seriously, just toss one of these things in a discrete location close to the front lines with a turret or two to scare away the ninjas.