Nick says he didn't know anything about being a Grimm when he bought the house that he lived in with Juliette, however Nick did not buy the house; it was Juliette's from before she met Nick.
Those window blinds in Nick's new home are not "three inches of solid steel". If they were, each of them would weigh about 2000 pounds. That kind of weight cannot be suspended from such tiny rails and each one of them would take as much effort to open and close as pushing a small car.