Craig: Thanks 1X10^6 I printed out your response and showed my neighbor. I think I've got him convinced, but only to fill every other hole. I especially like the idea of horizontally tying the columns together. Good idea. Do you just lay the 1/2" rebar on top the blocks and mortar over that for the next course or do you cut 1/2" notches in the top of the blocks in a course to set the rebar down in?