I have an area 18ft wide, 20ft deep and wanted to build a deck not connected to the house but more like a raised patio. I also wanted to make it 2 levels. Upper level would be 18ft wide, 12 ft deep, second lower level would be joined and be 18ft wide and 8ft deep. Imagine a big rectangle with a step down in the middle. Could I use 2x12's for the upper outside supports then 2x6's for the lower supports. That would give me a 6" step up right?
Ground is pretty level.
Just wanted to see if I could do this to make it look different. If this is not suggested I will just go with a 1 level 18ft wide, 20ft deep deck.

Thanks,
Dave

You could do that and it would work fine if your ground is really, really level. The step height would be 6". It would be easier to build this way but more cost effective if you would to build the deck using the 4x4 blocks.

Deckman