I need to build a small deck.  30" tall, 8' wide and 4' or 5' deep.

I was thinking of just using 4X4 treated for the supports.  But I wonder if they will rot off.  Are there different grades?  Basic design is pretty simple and pretty common.  It will not be attached to the house and probably won't be used much.  It's more of an entrance to a area that most people aren't going to use.

 

(deck.jpg)

deck.jpg (24KB - 509 downloads)

for a small project like this i would get some plastic laminated materials and build your own poles. nail theree 2 by 6 plastic together with different lenghts to them and sandwich pressure treated above ground and bolt.Don't know why the lumber guys have not come out with a plastic bottom pole. would make things so much better.   see they do have the treated with finger grooves above ground. Just the next step

Check out the 2nd pic in the link. http://www.bestfinishcarpentry.com/decks-framing.htm You can buy the pier forms and pour a concrete pier- a few inches above grade will do. Set your posts from there. You can even get anchor plates if you wish. Most lumber yards will carry something similar. good luck- jim

If it's not going to be attached to the house, you could simply "float" it on the ground. Setting out a couple patio blocks to set treated material on.
Another option is to "treat" the material with foundation coating. It drys solid and repels moisture and decay.
If I were to consider a post, I'd get Douglas Fur and treat it myself.
Water proofing sovent then after it drys, I'd use foundation coating on the part underground and up a few inches above. Then use some of the butal tape (used for window flashing) and secure that to the portion underground and slightly above the ground level.
The other consideration is to pour a floating slab. As long as the slab is below the rim of the house, so no water could get under siding and agaist the house wall . . . .
Concrete slab could be less money . .
I recently dug footings, set 5 courses of block (stem wall) and poured a 6 inch concrete cap with 2 steps up for my entry - cheaper then a wood / composit material deck of the same design.
My deck / porch will be maintinance free for ever . . . .   I reroded it also. Its strong enough that the backhoe/excavator can sit on it to dig out the basement, if the house ever burned . . . . .