Until minute 3:30, buildings/objectives show no armour type
Until escalation phase 4 buildings/objectives show normal armour type
At escalation phase 4 buildings/objectives show heavy armour type
Yet all buildings and objectives appear to take damage as though they had heavy armour type, explaining the potency of true damage against them. So, all buildings and objectives (besides listening posts and generators, those have normal armour and correctly display it) take 40% damage from normal damage type.