Building Your Small Cabin FloorFor wooden frame small cabin structures, use 2"x8" (or at least 2"x6") joists made from pressure treated timber.
Some newer pressure-treated wood chemicals may be corrosive to steel connectors, brackets, anchors and fasteners. Because of this manufacturers of these metal parts have developed newer, more corrosion-resistant versions of their products. Some of these are marketed as: ZMAX (heavier zinc coating), HDG (Hot Dip Galvanized), or STT300 (stainless steel Type 316L).
For example, when using Simpson Strong-Tie products, look for the part number ending with "Z", i.e., LUS24 vs. LUS24Z.
After your small cabin floor frame is built, it is time to place the subfloor sheeting. Use 5/8" pressure treated plywood. Three of these 4x8 ft sheets will nicely cover an 8x12 ft cabin floor.
Nail or screw plywood sheets no more than 8" apart on all floor joists.
I would stress again that you must use pressure treated timber for the cabin floor frame and subfloor sheeting. (And obviously support beams if you decided to go with this type of foundation/flooring structure).