If building with wood and this bothers you: raised floors is the easy solution. Use half height poles as piles. If the gap under wooden bits placed on ground is too much but raising ground is too high, try placing a half height piece and snapping a full height next to it and down - now you have half height off the ground with no ground/wall gap. EDIT: another (wood wasting) trick is to edge the bottom of you walls with beams. That should also fill in the wall/floor gap.