Regular wood is really weak. I switched to making all my building frames from core wood and haven't had any structural issues since then for 'normal' buildings. Core wood supports twice as much as regular wood and the log frames look spiffy.

Also use the hoe and some stone to raise the ground if you need more than 1 support beam to reach it. You can shape it into a little pillar with your pickaxe if you want it to look good.