I hung a 12 foot long by 12 inch wide shelf made of 5/4 pine in my daughters room to hold a ceramic doll collection. The shelf spanned the entire length of one wall. What I did to be sure it never fell on her was to drill holes into every stud along the wall. Then I screwed in large lag bolts, leaving them extended about 6 inches. (sorry I don't remember the size) After that I cut off the heads with a hack saw. I drilled corresponding holes in the back edge of the shelf and mounted it onto the bolts.... It never came down. I still wonder if the owner of that house after me ever took it down. I am sure they would have had some fun trying to remove those lag bolts with out heads on them. This was 11 years ago! Good luck!