Trey is right about the blocks being weaker when placed on their flat face. Block are non-structural, they don't hold houses up; its the reinforced concrete that gets poured in the "cells" of the block combined with a perimeter concrete beam that makes the "structure". 2 block side by side with the cells vertical with the next coarse or layer turned 90* to the previous coarse is the best way to stack them. Placed on a flat, level, well compacted surface,preferably concrete, this method of stacking would be ok up to about 4'. Fr. Franks 2 x 6's would be the way to go. You could even use 4 2 x 8's for the safty factor. As far as my credentials go, I'm the one that has to build the "over engineered"
structures that architects and engineers like Trey dream up.
I know ya gotta to do it that way because of the c. y . a. factor.
