Hi guys! I've been looking for 2"x10"x20' pressure treated wood for my ledger board and my end beam (doubled) and all I can find is non-treated pine. I was wondering what would be the proper replacement? Alternatives? See the plan attached. [ATTACH]81578[/ATTACH]

I'm having a single car attached garage built and was originally planning on having the builder do a screened porch off the back of the garage, but it doesn't appear to be within budget, so I am considering having him do only the garage and I would do the foundation for the screened porch. I would basically build a 120 sq ft deck and have him come back at a later date and do the columns, roof, etc. I'm thinking I could save several thousand doing it this way. Are there are any additional measures to be taken when building a deck that will eventually be covered and screened in? For instance, can the roof be supported by a 2ft cantilevered deck (2x10 joists), or should the support posts for the roof be positioned directly over the beam? Are 6x6 posts on 2 ft tall concrete pillars (2 ft is the frost line) with doubled up 2x12 beams sufficient to support the deck and roof? Should I dig a little below the frost line to be safe? Is it a bad idea to have a screened porch with roof on stilts that will be attached to another structure (the garage roof) that is sitting on a poured concrete foundation? My primary concern is the deck/screened porch settling and eventually pulling away from the garage and house over time.