Ground preparation for deck pier block
As requested,,,,It is hard to say how deep to dig down. When houses are built the contractor levels the ground and fills in shallow spots (much of the time). The trick is to dig down below the top soil it may be deeper. I usually find 6-8" gets me below the top soil but there have been a few that were closer to 18". I back fill the hole with crushed quarry and pack it so there is close to 1/2 the pier block above the ground level (home owner inspection flags if the post are within 6" of earth ). I live in Oregon so your inspection rules may be different. don't use crushed river rock as it really never locks – Ed Beal Apr 29 at 13:05   delete