How Much Sand Is Needed to Stop A Bullet?
This post is part of our series “What Will Stop a Bullet.” Please consider visiting this post's sponsor, “Premier Body Armor“
A few years ago there was a lot of buzz in the industry when rumors started to circulate about criminals filling their walls with sand in order to build bullet proof rooms. The theory suggests that about 3 and 1/2 inches of sand would be all that is required to stop a bullet since the standard distance between two pieces of drywall is about 3 and 1/2 inches. Sand bags have been used in military contexts for many years when building trenches and barricades so there is some general feelings that enough sand will stop a bullet.
Sand is a very heavy and dense material and so you can easily imagine it stopping a bullet but is less than 4 inches enough?
The most definitive testing seems to have been done by the pros over at The Box O' Truth in which they fired various handgun rounds and rifle rounds into boxes of sand. From all the tests “no rounds penetrated more than 6 inches” of sand. (See their article here)
Our friend over at BulletSafe also decided to put it to the test with a Desert Eagle and his results were slightly more successful but still he was unable to penetrate more than about 7 inches.
So it would seem that Sand is an effective stopper of bullets. I can understand why the military would use Sandbags for an effective cover shield. The great guys over at Tin Hat Ranch also did a balistics test with sand bags.
https://youtu.be/OiY80JgB26Q
I'm still not convinced that pouring sand into my walls is a good idea but it would likely slow down most handgun rounds enough to at very least make them far less lethal or potentially would stop them altogether. Sand is cheap and easy to find so there are many potential applications!
Why not try a more realistic test using the actual construction of a common house exterior wall filled with sand. Using building codes of most areas, an exterior wall would be something like Hardy plank siding over Tyvek on 1/2 inch plywood or chipboard, with 2 x 6 studs and 1/2 inch sheetrock on the interior with the cavity filled with sand. That would give you a sand filled wall about 6-3/4 inches thick. Much more realistic than cardboard boxes. Now run your tests.
The Real Person!
I hope in the future to do more mockups myself involving actual building construction and materials, but it probably won’t be for a while. But stay tuned!!
balls
Most places are not going to have 2×6 walls especially in the more low income areas that gang members would live, so testing with 2×4 is the way to go.(though I agree siding, vinyl not cement, OSB and drywall would be important) Or if we are talking urban apartment buildings it might even be cinder block and that would be a whole different test all together…
That’s the most ignorant and racist comment I’ve read in a long long time.
How many S8 apartments have you built? There’s nothing racist at all in John’s comment. Simply fact.
Thinking the same thing. I know Plenty of poor white people in s—— housing
Your ignorant if stating facts is racist sad you see through racist eyes where everything is racist
It’s actually not racist at all they’re just making a factual point that in lower income development neighborhoods the contractors tend to use poor quality materials which just happened to be in lower income neighborhoods has nothing to do with skin color.
Would is a very poor bullet stop. A 9 mm will go through 6 inches of wood. Don’t believe me go buy a couple of 6 x 6 put them in the ground shoot at them. You will be surprised at the effect then go and get a rifle Doesn’t even slow them down a 22 will go through standard exterior walls of houses
2×6 studs would equate to 5 1/2” of cavity space for sand. Not the 6 3/4” figure you stated.
I built a backstop for my shooting area. Two half-inch sheets of plywood with a 2 x 4 frame, then filled with sand. 9 mm bullets went through it easily. That’s 3 1/2 inches of sand and nearly an inch of plywood and it did nothing to stop my 9mm carbine. So you’re right about the stud space.
9mm out of a carbine is much different than 9mm out of a handgun, though. How much, though, depends entirely on the ammunition used. FMJ vs HP will also make a big difference as well.
could you give a R rating or value with that ?
Frank: That is a smart ass reply. But it is cute, something I might have thought too.
The Real Person!
Since you asked…
R-value of sand would depend on the actual moisture content. But typical R-value of sand would be somewhere around 0.5 most likely. In other words, not very good! But it probably would do okay with trapping residual heat during the day to release at night and vice versa.
But definitely not a recommended building material as far as placing inside your walls!
here’s what i found on r rating
https://www.windsor-csd.org/Downloads/R-ValueDensitiesChart2.pdf
Filling a wall on an existing house with sand would not be easy; I’m trying to imagine how you’d go about doing it. Fortifying your house with sandbags (or bags filled with whatever dirt you have in your back yard) like they show in the military manual on field fortifications makes a lot more sense, and it’s still invisible from the outside (you might want to add some shoring to your floor so it can handle the weight). And the hole you dug the dirt out of becomes either a few foxholes or pit traps, which further add to your fortification; it could even become a ditch that allows you to get out through a basement window without exposing yourself.
thank you from TOM C
BTW pit traps and all traps are illegal so… don’t do it
I wouldn’t fill my walls with sand mainly due to weight. As for 2×4 or 2×6 debate it depends on location. In the south 2×4 is sufficient for exterior walls however in the north 2×6 is required for snow weight and insulation requirements. Wouldn’t pea gravel be a more effective bullet stop though because the nature will disperse kinetic energy through the air gaps between the gravel. Notice F1 race tracks have gravel traps at high risk areas not sand, when a car going 180mph it stops in in feet. I’m sure there is a reason they don’t use sand most likely sand eventually gets hard like concrete as it dries. Daytona used to be literally on the beach before the raceway
Lots of practical jokers on here. Reason I am.putting up a back stop on level ground. Going to use 4×8 plywood.5 layers thick front and backwalls.i.e.7″ of plywood. Fill with dirt, thinking 2′ should be adequate.mostly pistol rounds and occasionally 30:06.reason’s all available free material.
In houses, the 24 studs become a weak point, about every 16 inches apart. The weight of sand is massive when stacked high, so could pry the drywall off the inside, or buckle it. For a 2 story house, earthquake resistance would be much reduced.
my question is this how deep of a box would i need to make and fill with either sand or shredded rubber or a mix of both to make an indoor shooting range in my basement for testing firing etc
Hi Guys,
I’m new at this. I just got concealed carry permit. I want to build a outdoor pistol range in my back yard. I live in the country, outside city limits on a little over 2 acres. There in nothing behind property accept woods. I have 2 ideas. First idea, I want to build a 2 walls out of decking 10×6 and fill with dirt.(6 inch thick with wood probably 7inch thick) Second idea is to make a wall out of 6×6 rail raid ties. I will be shooting 9mm, 380, 32 and 22 pistols. What is your thoughts or recommendations. Thank you
If you can create a sand berm, that is your best bet. Might need a bobcat, or backhoe… Railroad ties or multiple layers of plywood are good for a handful of rounds but once you start keyholing and it starts to splinter, it’s integrity is suspect.
Be sure to watch the angle of your target… You don’t want it to be completely vertical if it is a hard surface or else you can have rounds ricochet back toward you. You want it somewhere between 90 and 45°. the angle also increases the distance the projectile has to penetrate, much like the angled armor on the front of tanks.
I suggest a couple of vertical railroad ties with layers of plywood screwed into the front and supported on the back by angled railroad ties used like flying buttresses. From the top down it should form three sides of a box. Then back fill the box with sand until the sand is high enough to stop the rounds. And place a 2×4 across the front so that you know the max height that you can fire at before the sand is not thick enough to catch the round…
This article and the one mentioned has given me tremendous guidance for a new shooting range I am constructing.
I was originally going to build a berm behind the targets and Googled this article to determine how thick the berm would need to be.
My plan now is to construct a sand filled target using 6×8 posts with 3/4″ plywood front and back. The front plywood will be able to be periodically replaced. I will double or triple up the back sheets.
According to what I’m reading, this will be more than adequate for what I need without an eyesore and maintenance issue berm. Wish me luck.
I have some thoughts on how to provide protection for people in the interior of the house from stray bullets.
Not just bullets, remember a tornado, can throw rocks at your house with bullet force.
You can’t really fill your walls with sand because there is electrical wiring and electrical plug sockets in those walls. It just isn’t practical.
I think this is a solution.
Kelly Green Board, a plywood substitute, does a good job stopping bullets. It takes 2 inches of Green Board to stop a .45 bullet. Much much better at stopping a bullet than plywood.
I would recommend using, a 1 inch thick Kelly Green board on the outside of the house, on the exterior of the stud framing. This is double the usual thickness.
For the interior use a one half thick board for interior walls. This would replace the sheetrock board that one often sees in the interior of the house. Yes, replace sheetrock with this board.
I know that totals out to an inch and a half, one inch outside and half inch inside but the 3 1/2 gap in between the boards, insulation and the exterior weather shingles has to help stop a bullet.
Remember we are looking for a practical solution.
By the way, a half inch of Kelly Green board has an R value of “1” and it isn’t more expensive than regular plywood. So your wall assembly would have an R 3 before other considerations like the air gap, fiberglass insulation, and exterior shingles. Add 3 and a half inches of fiberglass insulation which is R11 and you have a decent R14 wall that can stop a bullet and not be too pricy.
This isn’t much more expensive than the way things are normally built. You are using a double thick board on the outside of the house. That will cost a bit more but not break the bank.
This board is intended to be used in this way so you won’t screw up your house, like you would if you did something crazy.
Besides your house won’t fall in because the walls are filled with sand.
I’m working on a new home construction project and have been doing some heavy research on the topic. Generally, these posts seem to be headed in the right direction. If I may add a few notes…
Sand is simply impractical for 99% of residential construction.
Build your walls with layers of protection. From the outside in…
5/16” Fiber cement exterior siding (common and relative low cost) – slows and spalls
Insulation foam layer – low cost – very little
1/2” Hardboard substrate – slows and spalls
15” wide 5/16” fiberglass panels – free from many recycling yards (you collect and cut to fit, placing them against the inside of the hardboard between the studs) – it’s an EXCELLENT slow/stop cross laminated material, has zero moisture content, is light, and cheap if you can find it
Standard fiberglass insulation – low low
1/2” hardboard inner wall. A bit more than drywall.
I’m this way you get a total of 1 5/8” of layered materials with gaps that allow any fragmented rounds to separate before encountering the next layer.
I’ll be testing soon but my guess is this will stop all pistol rounds and very likely most 5.56 and 7.62 as well.
PS: For the lower 42” I’m also adding an outer layer of accent rock siding – for an increased 1.5” of protection in my “ducking” zone.
PSS: Sand will be going in porch planters, under windows in particular – where about 9” of sand in front of these walls all but guarantees my defensive firing position (below windows) are fully bullet resistant.
None of this will add greatly to cost or are odd construction methods. Except for the fiberglass – which is unusual but won’t add much cost and is more than outweighed by its bullet trapping properties. I plan on adding as much of that as I can find during the build.
In the end it is also totally passive and looks 100% normal from outside or inside the home.
Curious for your comments
You might consider using rubber sheeting like they use in horse stalls as your front cover. It is self-healing when the bullets pass through and will not need replacing near as often, if ever.