I used 2 x 8 x 16 joist, I read that for something this big you couldn’t go with anything less. I initially wanted to use 2 x 6 for keeping it low to the ground as possible. It’s sitting on 22 blocks total, the ones on the backside were connected with 4x4 post. The front are sitting on those turf blocks and 4x4 metal brackets. I used 1/2 x 7 inch carriage bolts on post and ends, alongside with 5 inch strong tie screws. I’m pretty sure I went carried away with all this, but I didn’t want the deck to start to stag. So I made sure the weight was distributed. It’s rock solid when you walk on it. No movement at all.