So i may have found a place that sells decent railroad ties, a small local lumber yard has them at $21.99 each and they said they are clean on all four sides (not sure what this means). I am going to look at them tomorrow and see what they have and how solid they are. If I can go with the RR ties I can put a 12" space between them and use the decking over that which would give me plenty of strength that I would need. As for treating the hemlock, my friend says he know of a way to treat them using old motor oil and diesel.
If I have to go with using P.T. SYP it would be no less than 6x6, just so i would have more of a nailing area for the decking. I do plan on staggering the joints as well.
