How much concrete to stop bullets?

M

Mikul

New member
If you want to build a safe room, or even a safe house, how much concrete would you need to stop bullets... up to .308? I think that an easy way to do it might be to make concrete slabs and attach them to the beams. Of course, this won't work if the slabs need to be 6 inches thick.

If done right, it could look pretty nice too.

[This message has been edited by Mikul (edited August 04, 2000).]
 
Dave, I hope you're kidding.

If not, YEEESH! Is 6" minimal? I'd like to do this, but 6" of concrete from floor to ceiling is more than the wood joists in most homes can handle.

Is there any ballistic info on, um, well, stopping power, for concrete and other substances available?
 
Mikul, As an aside, I was told that two feet of concrete will stop a .50 BMG, though I can't provide veracity.
anodes.
 
Just a thought, but if you are interested in simply stopping bullets from going UP into the home, you could buy industrial lengths of kevlar in the appropriate thicknesses for the calibers you are worried about. Hang the kevlar on the beams/etc in the basement. I don't know how much that would cost over a rooms square footage, but you didn't mention price being an object either.
The kevlar would certainly weigh less than the concrete.
I think the amount of concrete needed to stop rifle rounds would be more than the joists could handle, as mentioned.
I assume this is not new construction.
 
6 inches will stop ball ammo.How about AP?

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Bob--- Age and deceit will overcome youth and speed.
I'm old and deceitful.
 
build3.gif

The room is 8' wide by 6' deep by 7' 11" high. The front wall is 6" thick, the back wall is 6" thick, and the roof is 6" thick at the coffer in the ceiling. It is entirely made of super-strong 6500 PSI concrete and weighs 7.5 tons! The steel door alone weighs over 300 pounds.
Share what you know, learn what you don't -- FUD
fud-nra.gif
 
This is from FM 90-10-1 availible from Palidin Press as "An Infantryman's Guide to Combat in Built up Areas"

Protection from single round of 5.56 at distances less than 50 meters [the 5.56 is penetrates more at 200 meters]: One thickness of sandbags, 2" unreinforced concrete wall, 55 gallon drum with water or sand, small ammo can filled with sand

7.62 & 50 BMG: The 7.62 is best at 600 meters [ie will penerate the most at that range]. At 25 meters 2" of concrete, or 8" of Cinder Block, or 5" dry sand, or 13" pine board. Note this is for a single round. A full auto weapon of any caliber is like a jack hammer the burst will wear away at the wall. With enough time and ammo a 5.56 or 7.62 will eat thru most any amount of concrete. AP bullets are supposed to do a little better but more likely to ricochet.

It is not clear about single rounds from a 50 but it sounds like 2" to 4" of concrete would stop single rounds of 50 BMG. Rebar will help a lot [any caliber] because has to break concrete and then cut rebar.


FUD: Is that in your house?
[This message has been edited by Glamdring (edited August 04, 2000).]

[This message has been edited by Glamdring (edited August 04, 2000).]

[This message has been edited by Glamdring (edited August 07, 2000).]
 
Mikul: We'd need more structural details of what you wanted; The whole home bullet proof? Just a room? In the basement? A basement under the room? DETAILS!

My first suggestion would be to forget making slabs and moving them into place; Concrete is HEAVY, in almost all cases you want to make it in place.

I've got a good book on stone house construction using the slip-form technique; You build wooden forms, line the face pointing out with stones, and pour concrete in behind; When the concrete has set enough to support itself, you jack the form up a bit, and lay another layer of stones. Nice thing is that it doesn't require a form which can support the weight of 8 feet of concrete, and allows the construction of extremely thick walls by one or two people.

The concrete will have to rest directly on a substantial footing. (What sort of geology are you contemplating building this house on? Clay? Sand? Solid rock?)

If you can arrange for the safe room to be below grade, the dirt around the house will provide substantial protection in and of itself.

I'd propose that you go for a concrete basement, appropriately thick. A concrete (Not cinder!) block wall, with the cells filled as you go up, would be easiest. Pre-fab concrete beams can be laid over that for a floor, then a slab poured over those for sufficient thickness. Then you continue up from there with a concrete/stone wall, and berm it.

For the entrance to the basement, safe doors with steel frames which can be set into concrete are available mail order. Back that up on the other side with what appears to be the inside of a gun safe, and even if they penetrate the door they might never guess what really lies behind it!

Now, other issues arise, such as providing an alternate escape route, means of communication, et cettera. What situation did you envision needing this safe room for, anyway?

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Sic semper tyrannis!
 
If your building a house from scratch, an earth sheltered house is a very cost effective [life cycle or long term cost] option. Materials usually run a bit more for building but energy cost and mait. are a lot less. Your using dirt for insulation which has a low R factor but you can use lots of it because it is *dirt* cheap :D
 
We seem to be describing a 1960's fallout shelter of reinforced concrete. Given the rogue states ruled by irrational zealots who have nuclear weapons, making such a "safe room" serve as a fallout shelter would be fairly easy and a wise course of action.
Are you in a floodplain? If so, then make it watertight to protect your stuff if you're not home and put in a snorkel to the roof for when you are. http://www.survivalring.org/fallout-shelters.html http://www.nuclearsurvival.com/below.htm
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Glamdring:
... FUD: Is that in your house?[/quote]Not yet, but I have it on order. I'm actually buying it for protection against hurricanes (souther Florida, you know) -- the shelter is suppose to withstand an F5 tornado which means that it'll hold up against a cat.5 hurricane without any problems. Although the shelter can/will do double duty as a super-strong mini-safe room.

By the way, I got your e-mail but my e-mail connection went down while I was in the process of replying and has been down ever since. I will try again later when it comes back up. Regards, FUD.
 
A concrete house is not as far fetched, or expense as one may think. For only a little bit more than a stick built house, you can build a home with insulated, concrete filled, steel reinforced, exterior walls.

There are a number of companies that offer a foam wall system, designed to be filled with poured concrete. A 14" foam block, would have a concrete core of approximately 8", and 1/2" steel reinforcing running 16" or 8" on center each way. That also gives you 3" of insulating foam on each side of the concrete, which provides far better insulation than standard framed homes. A channel is simply cut in the foam to run electric and plumbing. Siding and sheetrock are easily nailed or screwed to an internal plastic web "nailing strip", so your finished home looks just like any other house on the block. With the proper foundation, you could also have some interior concrete walls (for a safe room).

Add some 1" thick Lexan windows, steel security doors, a fire proof roof, (and gun slits?), and you have a concrete "Suburban Bunker".

My next home will be one of these (complete with remote controlled GE mini-guns hidden in the soffits) :)
 
GusGus: Of course, that foam block system isn't particularly bulletproof if the bullets don't chance to hit the concrete. I've also heard that termites love it; They can't actually eat the foam, but they hollow it out for living space.

Another construction technique I've seen involves building a circular foundation, and then inflating a form over it. Somebody then sprays the interior of the form with foam, then gunnite (Sprayed concrete). Interior walls are then stick built using standard techniques. These "foam domes" are very energy efficient, the hemispherical shape is very strong, and you could just have them build the gunnite up to the thickness you needed. I've heard of these homes shrugging off hits from wind blown telephone poles in huricanes.

here, check this out if you're interested: http://www.domebuilders.com/directory/
and http://www.concretedomes.com/

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Sic semper tyrannis!

[This message has been edited by Brett Bellmore (edited August 04, 2000).]
 
Fud...with your luck you will experience the first major Florida earthquake in modern history, your soil will liquify and the safe house will sink out of sight. Meanwhile the ground shaking will agitate your gators and they will all seek shelter in your still standing frame house which is being invaded by lost gypsies. But at least your cell phone will go weired so you get no warning of the approaching F5. After all is calm you will be heavily fined for feeding unclean meat to the gators, your wife will run over the dog with your pickup while leaving you.

Sam, would be glad to have you as a neighbor but afraid the county wouldn't survive the trauma.
 
For weight vs. cost considerations, how about spaced corrugated metal? Use several spaced layers and they would provide some structural support, some insulation (air spaces) and some ballistic protection...and won't burn.
 
Concrete:
If usin concrete, learn the specs and be sure that the supplier gives you good stuff. Have seen a lot of "short sacked" pours in residential and public buildings. Four sack with plenty of water is cheap, easy to pour and work; and has very little strength or longevity. Six sacks or more of cement per yard with minimum water is a bugger to work but will give you vastly greater strength.

To add to the dome idea, geodesic frame, skin it, then lots and lots of steel mesh, then high quality sand and cement mix. Gives you ferro cement structure which is strong and flexible....good enough for ship hulls. Paint it with elastomeric and make it blend in with the surroundings so it doesn't look like you are living in a golf ball. Cupola on top is great for bird watching through the scope on your ma deuce.

Sam
 
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Brett Bellmore:
GusGus: Of course, that foam block system isn't particularly bulletproof if the bullets don't chance to hit the concrete. I've also heard that termites love it; They can't actually eat the foam, but they hollow it out for living space.


[/quote]

Brett,
In the system we use, the foam is held together with a plastic web system. When the wall is poured, it is SOLID 8" concrete with 1/2" rebar 8" on center each way, not the inferior "post & beam" style used by others. We have not had termite problems with this system in the North East. In termite prone areas, a section of the exterior foam is removed, and the exposed concrete heavily treated. This method so far is working very well in the South.

Now, where do I get those mini-guns? :)
 
Probably the simplest way to do this is to build a wall from 8" or 12" concrete block, and fill the cores with either gravel or solid concrete.

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Beware the man with the S&W .357 Mag.
Chances are he knows how to use it.
 
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