I live in Georgia and we have more than our share of tornados. We usually go to the basement to my office during storms but I’ve decided that even though it’s underground on 3 sides, with only 3/4 plywood and sheet rock between us and the garage doors that it is no longer a viable option.
I’ve looked at FEMA  plans and I’ve scratched my head and come up with this idea but wanted to kind of say it out loud to someone to see if it sounds too crazy. The back part of the basement is almost completely underground. I have built a french drain around the outside of the basement due to some previous leakage problems and then decided to build flower gardens on top of the drain lines. The gardens are about 4 foot wide, held in place by landscaping times and then filled with 6 tons of tops soil (a shovel full at a time) and now the basement walls, to the roof are bermed in with dirt that just happens to go as high as the top of the foundation. That’s taken care of outside. For inside I’m going to construct a 4×4 frame, anchored to the slab and to the concrete walls, complete with crossing 4×4 in case the house caves in on top of us. The big question was how to deal with high speed flying projectiles (be they wood or bullet) and having looked at all the home and garden stores, have found that 40 pound bags of top soil at .97 a bag give a good solid footprint and stack almost as well as the sandbags I used to have to fill in some other un-named wars and countries. I figure, 4×4 frame, 3/4 inch plywood wall, bags of dirt stacked crosswise on two sides with a protected opening area for the door, followed by an additional outside 4×4 frame holding the dirt bags (or is that someone in office, I get confused), in place between the two walls. Since it will sit on a concrete slab the actual weigh is not a concern. I see this as both a storm shelter and a safe room (semi-safe anyway) with metal reinforced door with all the survival supplies packed inside. We are not going to bug out but will stay home. (Less than 20 miles from Atlanta, along I-20 but far enough off the road that stragglers shouldn’t come to our area since there are much nicer pickings between us and the main road.)
Anyway, that was a long winded way of asking if you think bags of top soil would be effective projectile stoppers. The only thing I have to test it with right now is 20 gauge shotshells with 00 buckshot and some .38 cartridges. I traded off all my assault rifles and pistols to help get out of debt, keeping only 15 .22 rifles, 4 .22 pistols, a dozen CZ-52 Czech pistols and a couple of pump 20 gauge shotguns (wife does not like and refused to fire 16 or 12 gauge) with many thousands of rounds for each weapon.
Take care and keep coming up with the neat links and ideas you have. I’ve read the ink off the pages of my copy of “Patriots” , so I’ll be replacing that soon 🙂 – Cliff
JWR Replies: Inch for inch, dry sand or gravel are at least twice as effective bullet stoppers than dry loam topsoil. And FWIW, I actually prefer gravel over sand, since bags of gravel do not have the “hourglass” dribble effect that is seen when sandbags filled with dry sand get hit by bullets. Yes, filling sandbags with gravel will be more laborious than buying commercially pre-filled bags of soil. But I recommend that you order several hundred sandbags and a few cubic yards of “3/4 minus” gravel, for upgrading your basement’s ballistic protection. A bonus is that gravel filled bags will also increase your basement shelter’s radioactive fallout shielding. The woven polypropylene sandbags  will last for decades if they aren’t left out in sunlight. Take a few minutes to watch this military training video: “Concealment does not Equal Cover.”  As you can see from the video, standard wood frame houses get thoroughly ventilated by modern high velocity rifle bullets, even from little .223 poodle shooters. You do not want to be in an unprotected wood frame house when the Schumer hits the fan. One important safety note: If stacking sand or gravel bags more than four feet high, it is essential that they be stabilized with stout shoring or crisscrossed steel cables, to prevent wall collapses. And if you plan to put up any overhead (ceiling) mass, be sure to consult a qualified engineer!
Regarding your plans to use a steel door: Be sure to get the heaviest gauge door that you can find and mount it a sturdy steel frame. Use at least four heavy duty hinges, and three deadbolts on the opposite side–top, middle, and bottom. I should also mention that hollow steel doors can be filled with gravel to increase their ballistic protection. Anything heavier–like extra steel plate–requires an extra heavy duty frame and massive hinges. (See my novel “Patriots”  for door bulletproofing details, including a handy formula for determining the weight of plate steel.)