Ok, I have a plan to build a free standing deck in my back yard. I can't decide though if I should sink the posts in the ground or just let it rest on concrete footers. It will be fairly low to the ground and about 15x15 is on size. I'm in nc, so it only gets cold for a month or 2.
Any one a deck expert?
I've built a few decks and it will vary depending on the soil. Try to avoid wood-to-ground contact even though it's treated lumber. Really soft soil might require an 18"x18" pad but usually the 8"x8" footers which are notched for the trusses will work just fine. Just set the outside truss in from the edge about 12" - 18" so that the footers are hidden when you trim out the perimeter.
2 - 2 x 10 trusses with 2 x 8 joists on 16" centers decked with 2 x 6 should be adequate for your 15' x 15' deck. This combination will put the top of the deck at 24" above grade unless you dig the footers in. If it's in the sun I would seriously consider using a composite material like "Timbertech", "Veranda" or similar to avoid cracking and warping over time.
Came back to say that if you use nails, be sure they are "hot-dipped" galvanized, ring-shank (3"). Deck screws are a better choice, but unless you go with stainless (yes, gulp), they are going to rust though in a few years. Even the ceramicoat kind won't last.