I have a little bit of a delema here and would like some input...

The only place I can build my barn is where there is a slight slope to the rear, about 18" over a 40 foot in one corner and about a 2' drop in the other rear corner. The wall height is going to be 13'6" to 14' high. I'm looking at an aprox size of 30x40'

There two options I' looking at...

1, building a retaining wall and back filling in and anchoring the post or build the wall on top of the concrete.

or

2, considering cost, possibly setting posts in the ground and building a form and pouring concrete between the posts to make a retaining wall and then back filling in in order to raise & level the ground and then pouring the concrete floor.

I have also took into consideration about the pressure treating process in that anything over 2" thick doesn't get properly treated throughout the the thickness of the wood, so I was also considering using 2x6's and making my own 6x6's using a staggered pattern which will also allow me to make them as long as needed.

Has anyone used either technique ?