Bullet-Proofing interior walls – Really!
Kind Sirs: I have a municipal client who needs to catch up to the realities of today, and make the iinside pay window more secure.
Consequently, I have to replace a standard stud-framed wall with a window and create a secure interior wall – 10′ high, 12′ wide. In the center will be (2) 3 X 3′ BP glass bank-type windows with the pass-through trays in the counter surface. These will be mounted in the normal aluminum storefront extrusion profiles.
But around the windows? I believe I’ve heard of layering plywood and 11-gauge sheet mild steel in a several-layer sandwich to break up a projectile before it could penetrate the final layer. This technique had the supposed advantage of being inexpensive and using relatively lightweight standard materials, even if it wouldn’t meet “7.62 NATO” specs. But, I can’t recall where I read it.
I can just see the potential liability claims from THIS job. . . Anyone got any thoughts on that?
Thanks – Forrest
Replies
Don't know where you are so I can't offer any specifics, but get in touch with a bank equipment supplier. They usually supply banks with BR glass (in stainless steel frames, not aluminum) and can sometimes supply BR material for walls. Probably a kevlar fabric.
USG makes a drywall sheet with a polycarbonate sheet attached to the back that is suposed to be very tough .It could be used for the first and last layer.
http://www.canmasonry.com/project.PDF
This link may help.
This came up here last spring. They do make bullet resistant drywall, I've seen it used quite a bit as I install banking equipment. Right now for the life of me I can't remember who makes it. Do a google search. It seems to me the first part of the name was Southern something or other.
some of the intake center sally ports had bullet proof glass.. about 1.5 " thick.. the walls were 8" block solid filled with cement groutMike Smith Rhode Island : Design / Build / Repair / Restore
i took apart a bullet proof enclosure... and really all it was 1/8 mild steel sheet with a 3"x 1/8 piece going over the seams... just drilled & screwed to the walls (exxon store)... i think i'd have em write the job order as bullet resistant...
A lot of so-called bullet proof glass is not BP really. Also, if a projecticle hits the glass dead on at right angles, the projecticle may be stopped but with a result of having a piece of the glass of like mass being ejected from the opposite side at a velocity somewhat less than that of the bullet.
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Excellence is its own reward!
You're exactly right, and that's why it's not called BP, but rather bullet resistant. But you can get the windows with a plastic layer on the safe side that was designed to restrain the broken glass. You can purchase it in varying degrees of resistance, from simple little pop guns up through multiple hits from assault rifles. All it takes is money and thickness. In all my time in bank security, I never had a drive-in window "tested". We used to tell the tellers that the easiest thing to do was to drop down below the counter, because the bad guys would only shoot at what they could see.
Edited 1/24/2003 11:48:35 PM ET by ELCID72
A gunsmith friend was given a piece of "bullet proof" perspex once to test. It was almost 2 inches thick.
Anything slow moving like .22, shotgun solids, larger heavier rifle projectiles etc were stopped. from memory even a 30.06 didnt make it. But a .222 went through like it was butter................
I saw in a military museum once a replica of an old police station from the 1800's. the walls were timber with a foot of gravel in between. the guys made a section up and fired all kinds at it, said nothing went through.
My gunsmith friend made a series of inch thick pine baffles. about a 4 inch gap between each. He tested it with a .270. found it wouldnt go though more than about 6. amazing sometimes what will or wont stop a bullet.
Wood Hoon
Mac,
I dealt with these issues when I was a maintenance super at a prison. We built window frames out of 3/16" mild steel and the window material was 1" thick BP glass. In the vans we built we used 1 layer of 1/2" lexan as a divider. The lexan is supposed to stop a 38 caliber plus P round at close range and did when we tried it. I suppose 2 layers would stop most stuff except the occasional armour piercing round. We also filled any block structure with concrete and used 5/8" rebar. On walls that were adjacent to inmate population we also layed a layer of a product called "hog walk" over the new block wall then layed another block wall up of 4" block sealing the hog walk in a stucco type concrete mix. This was in case of riot situations where the goal is usually to break into the control center and take the communications over as well as get to the keys.
One interesting thing we found out. Our main control center was built with 1" bullet proof glass window all around it. It had direct exposure to daily inmate traffic and was built in 1955. Well, in 1987 they had the New Mexico riots and they had the same set up. It is bullet proof but not............ax proof! So we immediately built steel bar set ups for ours. DanT
I understood the question to be concerning bullet proof drywall. If you want to talk glass as stated earlier there is bullet resistant glass, I don't think anyone calls it bullet proof anymore. We put in bank drive thru windows all the time. They are about two inches of glass. Very heavy and tricky to handle. They come with a pre built stainless frame. All of it is designed to sit in the window frame at an angle, something like five to ten degrees. The way it works is if you shoot at it head on the angle will deflect the projectile down and deflect the impact.
For interior applications they use see thru partitions made of some sort of thick resine that actualy traps the bullet.
If the bearing conditions are suitable, ICFs ought to work just fine.
DRC
If you were to use 4" of fibermat creet for the walls with some rebar. frame the window and door in the form. Keep the window on the small side.
As a municipal client, they should hire a licensed expert, an engineer or architect, to design to a specific performance specification. Those are the people who should be assuming the liability for the design, not you. Then they can hire a contractor (hopefully you) to install the materials as designed. If you attempt to engineer a structure involving public safety without a PE or architects license, you are asking for trouble.
If you want to make sure you get to do the work, you can propose to hire the designer and bill them for it.
A while back I say a segment on one of those shows on H&G about fiberglass panels they use to make bullet-resistant walls.
A little searching in your favorite search engine should turn up tons of stuff.
If you must choose between two evils, pick the one you've never tried before.
search at sweets
http://sweets.construction.com/index/search.htm
oops, search results didn't carry, enter bullet resistant.
bobl Volo Non Voleo Joe's BT Forum cheat sheet
Edited 1/28/2003 8:44:09 AM ET by bobl
There is worlds of research and companies that do this sort of thing.
One thing I learned is that when you are attempting to get maximum armor value out of a small/thin area an open air section works well. The idea is to have the bullet piece something hard, such as a steel sheet. Then hit air space. Then another piece of steel. Many bullets will fragment some in the air space, and more when they his something hard. Smaller pieces have less mass thus less penetration potential.
This is used on parts of the armor of the Bradley Fighting Vehicle, and is said to greatly increase the armors effectiveness. A bullet that'll easily pierce a half inch of solid steel, may not piece 2 quarter inch pieces an inch, or even less, apart. Of course, I'm talking high velocity rifles to pierce a half inch stell plate, not handguns.