I would disagree... SPF No. 1/2 is easily obtainable in any big box store or lumber yard. 'Select' may be special order, but you'll find it in a yard. Neither would show up in an exterior application. We live in Ontario, so Spruce-Pine-Fir is our option. BC would be using D.Fir.
Pressure-treating is a process performed on the wood - the wood retains its structural properties. It is definitely referenced for use in the Ontario Building Code. It has its applications... Sill plates when close to grade and especially decks and outdoor structures for the common person. ACQ or CA are the treatments available to us in Canada with CCA pretty much gone for the average home owner yet still available for certain construction. Bridges, railway ties, etc. are another matter and are treated with creosote. Americans have more options than we do, but it doesn't matter...
While some pressure-treated wood it may not pass the visual grading of Select or No. 1/2, it would fall into No. 3 for sure. The wood is not 'garbage', it is only treated so that it survives outside. You can buy PSL Parallams that have been treated for that matter.
SPF No. 3 is stronger than the best 'Select' grade cedar as confirmed by the Canadian Wood Council (check out the CWC Span Book).
The green coloured pressure-treated products are leaving the residential market. Brown is available more so at Lowes, etc. Home Depot is selling the MicroPro Sienna now which, to me, is a better brown which better matches a 'cedar' type look. The pressure-treated deck will last forever provided that you buy 'Ground Contact' rated when in contact with the ground and that you field treat the end cuts with preservative. Use hot-dipped galvanized (HDG) nails and hangers. If you use screws for the structure, they must be stainless steel. Deck boards can be put down with the coloured screws which are rated for ACQ/CA.
To the OP:
1. Skip the new fancy product and go with the tried and true pressure-treated. If you want to splurge, upgrade the deck boards to cedar (I wouldn't bother - especially if you're staining). All wood must be maintained to keep it looking proper. It will turn to shit if you do not,
2. Get a Building Permit, hire a good contractor and spend the money on proper design and construction (foundations, etc.). Upgrade joists, beams, posts for a super-stiff and solid deck, and
3. Construction your railings as per the Ontario Building Code. People do such a shitty job, that the OBC actually has pictures on how to do it properly.
