Orks must get 70 Ork Population and an upgrade from their Orky Settlement. Eldar need to research Mobilise for War from their Soul Shrine. To climb to Tier 3, the Space Marines and Chaos must build their vehicle facility along with their second research building and research an upgrade from the HQ. In this tier you are given access to vehicles, anti-vehicle weapons, and more powerful weaponry and upgrades. Orks must amass 50 Ork Population and construct the Pile O Gunz!. To progress to the next tier Space Marines and Chaos have to build an Armoury, a barracks and purchase an upgrade from their HQ. Heavy weapons and other beginning researches are available in this tier after completion of the armoury or equivalent structure. Your access to units is dependent upon the race. You are given a builder and an HQ to start. It should be noted however, that with the last few patches, the time required to research the higher tiers has decreased. In the original Dawn Of War, there were only 3 tiers. In Dawn Of War the tier system is used to gain additional researches, new weapon upgrades, more powerful units and more powerful abilities.

Dawn of war 2 guide