The building has max durability of 20000 when the building quality is 100. So the formula of the building scaling will be:
(Building durability) / 2 / 100 = (Building Quality)
Then the building quality goes into the influence of the crafting item.
Full plate helm
Common ingots 50 %
Blacksmith's hammer 10 %
Forge and anvil 10 %<------ The building Quality multiplied by this percent
Skill influence 30 %