Make sure you're considering all of the factors in designing this and see if you can get some sort of plan review from somebody with experience.

For example, if you frame the deck with 2x6 only, you will generally not be able to attach the safety railings strongly enough to meet the 200 pound midpoint all directions force resistance requirement according to the testing done by some reputable engineering journals.

You also have to think about snow loads, springiness from using minimum code spacings and spannings, how to attach it to the house securely, type of lumber used on the various components, strength of the staircases (if any), etc.