I need to put a deck and stairs to gain access to the second floor of my shop. It is set up to be an apartment up there but unfinished. Can you guys guide me to make sure it is strong and secured properly? What size ledger and how to make sure it doesn't fall off down the road. What size joists and spacing? What size and how many support posts? I am thinking the size I want us 8 x 12. Here is a pic of where I want it built.