Gun room build
I have been reading quite a bit about building science, and this site has been a tremendous help – thank you! However, I have a bit of a unique situation that I wanted to run by you guys to make sure I wasn’t missing anything.
I have a current home where I would like to build a gun room instead of using multiple, hard-to-navigate safes. A spot in my basement has an 8′ ceiling from the concrete slab, so the dimensions will be tight. I take gun safety extremely serious, so I would like to build this correctly. In an ideal situation, I would use cast-in-place concrete but that is not an option here. So, this is what I was thinking for the wall (From the exterior of the room to the interior):
[Just for looks and to hide the steel, 2×4 framed wall with drywall built after the structure below is built]
1. 1/2″ Steel, placed horizontally
2. 1/2″ Steel, placed vertically
3. Studs; filled with Rockwool Safe n’ Sound
4. Horizontal furring strips to I can clear the bolt head.
5. 1/2″ Plywood
6. 5/8″ Drywall
I have a few questions:
1) In regards to the stud framing, I am concerned about the weight of the steel plates. I have two plates – one vertical and one horizontal – to cut the weight (For moving them/installation) to a reasonable weight as well as so I can overlap the seems. The weight of the plates alone will be 42 lbs per square foot (21lbs/sf/sheet); I also have to factor in the finishes on the interior (Racks, firearms, etc.). I have used Weyerhaeuser TimberStrand LSL’s before and I love how straight they are. I know they also have columns, which may also work to carry the load. I don’t necessarily care about the price as the room will be 200ish square feet.
2. Any recommendations for assembling the wall? My thoughts were to build the studs, then drill a bolt pattern on the steel plates, place the plates in place, weld, sand and repeat with the vertical studs. Once completed, run a bolt from the steel plates through the stud to fasten everything in place. Fortunately I have family members to help with labor and I can weld / have all of the equipment.
3. Since this room will be full of expensive equipment, I want to focus on conditioning it properly. I do have an ERV that taps INTO my HVAC system – not ideal, I know. Would this work as oppose to a separate, standalone system such as Zehnder? Should I put this room on a separate zone (It will be connected to part of a finished basement (600ish sf)? Also, the steel will be facing an unconditioned basement in a Zone 4 climate. Should I be worried about condensation?
I’m sure I missed something, but any other ideas or suggestions will be more than welcome :). Thank you in advance!
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Replies
I'm not really interested in the details of this project but will say you seem to understand building science, so treat the room your constructing as you would a house. Structurally sound, tight and moisture managed/ventilated as needed.
I'm sure you have some dessicant handy as well.
Maybe park a shipping container in your basement..
Good luck
A dehumidifier with pump and a small baseboard heater or branch from the existing hvac should take care of conditioning. Make sure you have a vapor barrier in the floor and air sealed walls/ceiling.
Is this totally freestanding or sharing concrete basement walls? If concrete wall are involved, follow guidance for insulating them.
Doubled 1/2 steel seems excessive, particularly since you didn’t mention a roof! Sawing through the kitchen floor to go down seems pretty easy.
The mechanical's are 5 feet from where the room will be and are grossly over-sized for the homes. However, they're geothermal and I can section them off quite easily. I'm just going to run a trunk to the room; I just wasn't sure if I should run that on the same zone as the rest of the finished basement or if I should separate them. A dehumidifier is a good idea! That, I'm not too familiar with. I'd like the room to be as "clean" (Decluttered) as possible. Can you recommend a small one for the room? Can I have multiple zones so one unit can be independently controlled for the room and rest of the basement?
So, I have a concrete floor that is not insulated. Like I said, the current ceiling height from the slab to the joists is 8' where the gun room will be (The floor above was dropped intentionally when the previous owner built it). Any recommendations for flooring without eating into the headroom too much?
The room will be on one exterior wall (12" foundation, uninsulated cast-in-place). Therefore, I'll have to insulate it. I wasn't going to add steel along that wall since the concrete will be sufficient. I may, however, have to frame the room against the wall (Perpendicular walls), then insulate between them so the steel butts up against the concrete wall. I can add a break but I'd prefer not to have the concrete wall > insulation > steel, due to the gap created by the insulation.
I also thought 1/2" steel was excessive! But, the price difference is minimal and the weight is a nonissue (Up to 1/2"). The only downside is it will take more time, which I am ok with.
Ahh, the roof! I forgot about that. I have 2x10 joists (12" on center) for the floor above and then 2x6's which hold the new floor above that (Remember, the previous owner dropped the floor; I raised it to make it even). Therefore, the original joists are already holding more weight that they originally would. Those 2x10 joists sit on the concrete foundation on the exterior walls and steel beams on the interior (The steel beam splits the home in half - 15' span). My thought was to predrill a bolt pattern and bolt the steel plates (Just a single 1/2" plate) to the joists then support the edges with a 2x. I really haven't given this too much thought. Any ideas are welcome!
> gun room
Does this room need to be bulletproof? Zombie-proof? Lunatic-proof? Welder-proof? What bounds your threat model here - what risks are you trying to protect against?
Half inch steel plate is 20.4 pounds per square foot, or 652lbs per 48x96" sheet. Moving one of these plates around around might make cast-in-place-concrete look simple. You've welded before - do you have experience moving this sort of thing? Crushing aside, if you take the horizontal plate up to 4ft and drop it straight down (which is not a small risk with this mode of assembly!), that would sever the strongest bone in your body, keep going, and perhaps even crack your concrete slab underneath.
> Should I be worried about condensation?
Absolutely. The heads of those bolts are going to be in very close thermal contact with the basement, and if you're conditioning this room to comfortable humidity, condensation may gather there.
> Once completed, run a bolt from the steel plates through the stud to fasten everything in place.
I don't know that I would want to hang that much weight off of carriage bolts drilled sideways into 2x lumber, without any embedment into the slab. I would check out whether 4x4 or even 6x6 posts as studs are more appropriate. I would also check whether it would be a better idea to hang the steel plates off of opposite sides of the stud so that the wall is theoretically balanced. Whatever you do, don't skimp on anchors to both floor and ceiling.
> steel plates
Thought about doing something composite? A steel-brick-steel sandwich, perhaps? Even just a sand or sand-topping-mix fill... In terminal ballistics additional thickness of a hard material is very useful. It's even useful structurally - we carry huge loads on 'lally columns with 0.06" sidewall steel sheets around a concrete core.
I don't have a lot of awareness of layout here - is this wall going on all four sides? Are you building the door like this? What does the door connect to?
Bullet proof, zombie proof, lunatic proof - nope! I am simply just trying to lock up firearms in a responsible manor; there will be a vault door as well. As I mentioned in my previous reply above, the 1/2" is excessive but doesn't cost much more. Just seems like a no brainer. Maybe I am being too cautious with the double layer, overlapping seems on the two steel plates, but I'd rather be safe than sorry. My goal is to just keep people out for as long as possible. I have high-end safes (Brown) and those too can be breached - if someone wants to get in, they will.
You are correct, that's a lot of steel. Maybe I am getting too carried away. The original owner of the house was a commercial architect and overbuilt the home for some reason. My concrete slab is 10" (No idea why) and not a single crack! I work in concrete and they did an incredible job with the pour. Fortunately (Or maybe unfortunately :P) I am blue collar so I am used to heavy weights. There will be 4-8 of us working on it so I think we'll be ok! Instead of stacking the steel horizontally, I can just offset them (Not sure why I didn't think of that - probably because I was thinking of insulation, which is obviously easier to work with than steel plates).
I looked into the composite route but steel was significantly cheaper. I buy more steel at work than I care to count so I get a pretty good price. We do share the same concern: balance. I was just looking at Simpson ties that could work. Something I still have to look into. Any recomendations?
So the TimberStrands are 2x's but I was looking at their column solution, Parallam: 4x4, 4x6, 6x6, 5.25x9.25, etc.. It's probably best to call Weyerhaeuser and ask. Since I'd like to hide the steel in the unfinished part of the basement, maybe I could do: Frame, steel, frame - and bolt them together, essentially sandwiching the steel. If I do this, would it be best to insulate both sides to keep that steel warm?
For the door, I'll be welding a steel frame for a vault door (By Amsec, Sturdy, etc.).
Sorry, it's hard to picture the layout. I have an exterior wall on one side of the room; I was going to insulate that, then build out three other walls, forming a rectangle.
> Frame, steel, frame - and bolt them together, essentially sandwiching the steel. If I do this, would it be best to insulate both sides to keep that steel warm?
If you do this, the bolts are going to thermally bridge steel to steel extremely well, rendering cavity insulation relatively useless. You would be relying on insulation on one side of the steel wall.
> There will be 4-8 of us working on it so I think we'll be ok!
Bet your life on it? Bet the deed to your house? Are you insured for this task? Surely you've heard stories of uninsured roofers falling off a roof and being compensated for their paralysis with more than the house is worth. Even four people who can each powerlift 650lbs individually cannot necessarily maneuver a 650lb sheet good into place safely, working together. The center of mass is two to four feet away from any feasible handhold, and additional people are mostly going to be using the pinch strength of their thumb muscles rather than their biceps.
> I looked into the composite route but steel was significantly cheaper.
Than what, specifically? It seems like the most expensive thing possible - and almost none of that is raw material cost.
> I am simply just trying to lock up firearms in a responsible manor; there will be a vault door as well.
All you need for that is an inconspicuous place with a hidden room, combined with a locked door.
Can you present a plausible scenario where this sort of build actually serves your interests? One where attempting to go through walls is the easiest way for the adversary to get what he wants? That's not even... it's a mental pathology to create such 'movie-plot security', but if you can't even come up with a movie plot threat that sounds reasonable, it's a hint that you might be going overboard. https://www.schneier.com/blog/archives/2005/09/movie-plot_thre.html
I would advise you to read zephyr7's advice closely, with one addendum: A traditional interior plaster on expanded-metal lathe is likely going to be much stronger than drywall & hardware cloth, especially in multiple layers. https://www.youtube.com/watch?v=CoF5F9AuZ98
Ahh, sorry, I meant Studs with Insulation > Steel Plates > Studs with Insulation. However, I guess that bolts would still transfer. With that said though, it's in a basement so I don't think it would be that big of a deal? It's about 65 degrees down there.
Well, yes, there are 6 people in my family who shoot regularly so they better help. Just kidding, yes, we all thought it would be a fun project so we're in it together. Also, fortunately, we do have excavators, skid steers and such so it makes the task much easier. The exterior steps from the basement are 20 feet from where the room will be. The bucket on the excavator can simply slide the steel in, onto a dolly and we just have to stand them up into place. I just moved a 1,000 pound safe with 2 other guys into the basement and that was a cakewalk!
Well, I once had a firearm stolen that was locked in a closet in my locked house. Let's just say: live and learn. It cost me quite a few thousand dollars in legal fees. Because of this, I'd rather be safe than sorry.
Thanks for the tip! I'll look into it.
Like any project you need to define your requirements and the look at ways of meeting them.
Do you have a specific temp and humidity you need or just non condensing? For non condensing and not a huge temp swing, working off the basement zone should be fine. If you need to hold museum level temps and humidity, consult some pros.
Stand alone dehumidifiers are the most cost effective. Check consumer reports or similar.
Floor needs a vapor barrier. Does the slab have poly underneath? Foam insulation is required if there are any moisture transmitting coverings.
Exterior walls need to be insulated to code. Use rigid foam board, reclaimed is best.
I don’t have a lot of advice on the zombie proofing. Again define your requirements and consider the design options to meet those requirements.
I do like playing the how to break in game though. I was thinking just sawzalling the bottom plates and where you attach to the concrete wall, but you might able to fit the plates reasonably tight. I think from what you describe, I am still going through the kitchen floor, I just need to cut the joists the ceiling is hung from too. But man you do have more floor joists than average.
In terms of temp/humidity, not really. I just want to avoid moisture as much as possible to shift any risk of rust. I'd like to keep the room 70ish.
Oddly enough, I could not see any poly under the slab; there is a ton of crushed stone, though. The basement is bone dry. I did the "tape plastic to the slab" test and it passed. So, I'm not really sure what the deal is.
Definitely not in this for Zombie proofing haha. My thoughts were to lay the bottom plates and then cut the steel flush with the floor on the outside so the bottom plate would be on the interior side of the room. Also, as I mentioned above in a previous reply, I'd lay a single steel plate on the ceiling and then weld the steel plate on the ceiling to those on the walls. Effectively creating a 'box.'
With all that said, I'm going to look into the mesh idea.
I design a lot of secure facility stuff for datacenters. We don’t use steel plate in the walls — it’s a HUGE PITA! The weight IS a big deal, and drilling holes in steel in the field will have you hating life pretty quick.
What I usually do for medium security levels is to sandwich a layer of 1/2” mesh hardware cloth between two sheets of 5/8” drywall. You would be amazed how much reinforcement the drywall gets from that hardware cloth: it makes it nearly impossible to cut through the wall without power tools. If you put a double layer of 5/8” drywall on both sides of studs, you also get a 2 hour firewall.
If you really want to put sheet steel in your walls, use 1/16” or 1/8” cold rolled steel sheet, then sandwich it between two layers of 5/8” drywall. “Cold rolled” is work hardened, which makes it harder. Have a fab shop punch holes in the steel sheet to line up with your studs. Have them punch something like 1/2” or larger holes. You want big holes to make it easier to get your drywall screws lined up.
Don’t waste money on thick steel plate. It gains you almost nothing. There are two rules to follows in the security world:
1- security is like an onion, it is implemented in layers. What are your layers? Probably something like “front door, alarm system, gun room door”. You really have another layer too: someone needs to KNOW you have something fancy in your home. We’ll get to that in a moment...
2- you can’t make it impossible to steal something. Don’t even think about that. What you’re doing it making it so that it is not worth the effort to steal YOUR something. There is an important distinction. I like to joke that “real security is the “use of deadly force authorized sign”, but that pretty much limits you to one customer when you’re a consultant.
A regular burglar is probably going to get scared off by an alarm system, or will at least move fast in your home before they leave. Hardware cloth in a wall will PREVENT them from punching through the wall with a hammer, even a sleeve hammer. It will also prevent a drywall saw from working. You’d really be amazed how beefy a wall built like that actually is. You just made it so the burglar doesn’t have the time to steal your stuff, so you’re safe.
Now let’s assume the burglar is a little more determined. He knows you have stuff he wants, and waits until you’re out of town. Or maybe he found a way to disable your alarm system. Now what? He still needs a LOT of time to cut through the wall. Steel sheet is harder to penetrate than hardware cloth, and will make a difference if mr. Burglar brought a sawzall. Put a second alarm in your gun safe with a cellular link and battery backup. Install it INSIDE your gun safe with a motion sensor. Or build your wall like this: 5/8” drywall, hardware cloth, 1/4” drywall, hardware cloth, 5/8” drywall, stud. Wire the alarm to sense a closed circuit (like a sawzall blade) between the two sheets of hardware cloth. If a short circuit is detected, call IMMEDIATELY for police. Set things up with your alarm company so that they tell the police someone is trying to cut into your gun room. Make this a silent alarm. Now mr. Burglar gets a surprise visit from law enforcement while he’s still working on cutting through your beefy wall.
If someone is TOTALLY determined to get your stuff, you really can’t stop them. Don’t waste money trying. Just make things beefy enough to stop anything you expect might reasonably happen. I’ve described some inexpensive walls that are very effective and don’t need any fancy materials or difficult construction techniques. I’ve used these wall assemblies on commercial projects with good results. The best thing you can do is plan the layers of your security so that a thief gets caught, gives up, or gets scared away before getting to your stuff.
BTW, pocket doors, when built for security, are far more difficult to force open than swinging doors. You want tracks on the top AND the bottom, and you want the door to go into the frame all the way around so that any attempts to force the door get transferred to the frame and not the door hardware. If you use a regular door, use a three point lock mechanism and commercial hinges with the locking tabs. Build a STRONG frame. Reinforce anything that takes force (hinges and lock strike plates). Hiding some steel angle in the frame, or building king studs like mini flitch plates makes a BIG difference on the ability of a door to resist a battering ram.
There is a lot more, but this should give you some good ideas.
Bill
Hey Bill! Thank you for your lengthy reply - I greatly appreciate your response. That's an interesting idea. To be honest, I do like the idea of having a solid piece of steel, and I think my other family members would prefer it to be an over sized safe.
As I mentioned in another reply, I can lower the sheets of steel with an excavator into the basement onto a dolly - just have to stand them up into place. I know cold-rolled steel is significantly more expensive but since its much harder, I can use a thinner sheet. Maybe a hybrid system? Drywall/Mesh/Drywall > Studs > Steel > Studs > Drywall/Mesh/Drywall.
Fortunately, I do have a machine shop and can have guys predrill holes in the steel so nothing is done on-site other than welding. And honestly, if a hole is off, I can just add another stud. Oversizing the hole is a great idea though - thank you!
For the door, I will have a vault door installed with a steel frame. The door will be in a room behind a hidden door using a vertical ship lap wall with sugatsune hardware (So the vertical joints blend in). The reason for studs and drywall on the exterior side of the room is to hide the steel, setting off any red flags. I will also have a motion sensor and camera tied into my current security system. Thanks again for all of the tips!
Bill,
Your comments on GBA have led me to believe that you might very well have the coolest job in the world! You should start a blog
That’s the second time someone has asked me to start a blog. The first was friends of mine in Maryland telling me I should blog about Maryland crab soup because I love the stuff and get it everywhere I go when I’m out there :-)
I do a lot of consulting work on critical facilities, usually telecommunications sites. There are a lot of security requirements in these places. I specialize in what I call “integration” — making everything work together as a system. A lot of the time my job is to improve overall energy efficiency of the facilities, and since these places use MASSIVE amounts of energy, even small 1/2% improvements can mean thousands of dollars a month in savings.
Most of the job is just being creative. It’s all applied physics. Look at the problem, THINK about the problem, come up with a solution. Don’t be afraid to try a few times or make refinements. Since every site is different, every solution I design tends to be different too. I also try not to be limited to stuff in a catalog. If you have metal fabricating skills, or our friendly with a fabricator, you can DESIGN things and have them made to your spec. This works for residential too, although residential usually needs a higher finish level. My stuff is very results oriented, so bare galvanized steel is fine. Maybe I should do lofts, those guys like the industrial look :-)
Bill
I agree with Rick - a blog would be super cool. At least you know you'll have 3 subscribers ;).
Have you ever used ClarkeDietrich Barrier Mesh? Looks like an interesting solution behind a layer of drywall. Though, fixing a rack to the stud may be a royal you know what. Regardless, that's an easy fix.
Why don't you just lay block?
When I read your first post, you mention ideal is cast concrete, but ya, pretty tough in a basement, but the thought of using cementitous material was considered, so I was thinking 6" or 8" block is best bang for buck (pardon the pun) in terms of ease and robustness. But then it jumped to sandwiching 1/2 steel plates?
Risinger did a video of shooting guns at houses a while back, I think block wall won. He also had a few safe and gun rooms in recent videos. I think if you google that and it should pop up on youtube, maybe check it out for some inspiration.
My personal thoughts: I think block is your best bet, getting block in your basement will be easy. you can even rebar the hell out of it and fill it with concrete if you want (except the top course). no one is getting through that. have strapping on the outside side for drywall. If you want drywall on the inside, sheets of 1/2" ply on the inside against the block then drywall screwed to the ply, that way you have free reign to tapcon racks anywhere on the wall, through the ply and into the block. Save the 1/2" Steel for the custom vault door. Insulate the foundation wall, if its not waterproofed from the outside, consider an interior vapour barrier. if you have existing basement hvac, just run a branch into the vault, no need for a separate zone. I don't think hvac is totally necessary if the vault isn't going to be used often, it would still be within a conditioned space, but I'm sure the HVAC gurus on here can say more about that. It at least would get some air circulation. I also don't think ventilation is important here unless you're actually going to use it as a safe room (ie: several people staying in there for a long time). I think the most important thing for conditioning this particular space is a good dehumidifier. Just run a plug in dehumidifer, you can even preplumb a drain for it so you don't have to physically dump the condensate every so often.
Jamie, changing to block was my first thought as well. For extra protection the OP could lay two layers of 4" solid block with expanded metal lathe in the middle; that would make it hard to get through with a sledgehammer. No need for strapping or drywall on the interior; just plaster directly over the block. Racks can be tapconned as you suggest.
I thought about the concrete route, but I figured steel would be somewhat easier. However, second thought, maybe not. My first idea was to weld a steel box from the sides to the ceiling so it's one solid piece. With concrete, I still have to figure out a ceiling. The thing that blows my mind with safes is, they advertise a 1/4" steel door but then the sides are only 11 or 13 gauge. Why go through the door when the weak point is the side? That goes back to the saying, you're only as strong as your weakest point. I have googled relentlessly "safe rooms," "vault rooms," "gun rooms," etc., and I find it interesting how many people have a 2x4 wall, plywood, sheetrock and then a $4,000 vault door. Why? Just doesn't make sense.
I just looked on Nudura's website and can do a 6" core wall. However, I'd have to cut my current slab to install proper footers. If I go this route, any suggestions for a ceiling? Maybe run an "L" bracket which overhangs into the interior by a few inches, predrilled so I can bolt / weld the two together? The "L" bracket could be sunken into the ICF walls a few inches; maybe even drill out some holes to get a solid hold within the concrete. I'd like to have a finished ceiling, too, though, so I would have to frame it for electrical, lights and finally drywall. But again, there isn't much headroom so framing down a few inches will not be idea. Open to suggestions!
Block has the advantage of coming in convenient, manageable “block sized” pieces too :-) much easier than huge sheets of steel.
The idea with the door being beefy is to protect the locking mechanism. It’s surprisingly difficult to go through the sides, and a drill doesn’t do much on the sides — you have to cut pieces out.
Many safe rooms are built by and for clueless people. You need only one “tool” to go through a normal drywall wall: a good shoe. I’ve seen people punch a hole with their fist, and I even saw someone get mad and punch a hole through a wall with an umbrella once. Drywall isn’t all that strong on its own. If you put hardware cloth between two layers, all the easy “bash a hole” stuff stops and you have to cut it with power tools.
Remember what I said too, your goal is really to slow the thief down enough that they give up or get caught before they can get your stuff. You don’t need to build a bank vault here. Put the savings into a good monitored alarm system — you’ll get more for your money that way.
Bill
Another way to look at it:
If we lived in a world where the thief could reliably lockpick his way into a vault with destructive application of dollar bill lockpicks, and it cost you something to build a better lock to raise the number of dollar bills, how much do you think the thief is willing to spend to get into the vault? What are the assets being protected? It makes no sense to protect a $300 necklace with a $5000 vault, for you, because the necklace can be replaced. But from the other side of things... does it make sense for the thief to steal a $300 necklace with $500 in lockpicks? Why does the thief even know what's in the vault?
Bank vaults come correct because thieves have a firm idea that there's large amounts of money in them.
If you keep $200k in cash in your safe (as a marijuana dispensary might), and this is publicly known, then expect to have to fend off thieves willing to assume $200k in risk & tools. If not... don't. Obscurity is the largest part of residential security.
Burninate, I like your analogy :-)
Bill
Burninate, I do have a significant collection consisting of high-end rifles, scopes, pistols, ammo and one-off collector items that were custom made. Therefore, I don't mind spending the money to safeguard them. They are insured so I'm not as worried about the money part (In the sense of a fire) as I am about the safety part (Theft). Due to our asinine gun laws and my recent job relocation, I am unable to move my collection with me so I have to carry a property to store everything. I do have a Crestron system that is tied into my security system that is monitored 24/7.
Zephyr7, if I go the 5/8" Drywall/Steel Barrier Mesh/5/8" Drywall route, is there a way to bump it up a notch. Do you think it's worth Drywall/Mesh/Drywall then a 2x8 stud then another layer of Drywall/Mesh/Drywall? Maybe a concrete block stack on the exterior wall of the room? Sorry for all of the questions - I just keep going back and forth on what to do.
Hello all,
Talking about steel and concrete on this site is like talking about sex, guns and religion at the family christmas. Then add guns! What a great place this is that we can all remain helpful and respectful of others. Thanks.
As far as the safe goes, I just completed my own and planned for it when pouring the original foundation. Their has been some great suggestions here. I would just add that I strongly suggest a dehumidifier and keep the room around 45% RH. I would not worry about air flow and temperature as the guns wont complian about that. My dehumidifier adds a small amount of heat anyway and has done the trick. Otherwise its closed up tight for water, air, fire and people. I also like your idea of hiding it! Good luck
Shawn
That's funny, but you're so right. However, for something as serious as this, I believe steel and concrete are warranted :) Best of luck to you too, Shawn!
Seems like it would be cheaper and easier to just move to a better neighborhood.
But then again, everyone I know leaves the keys in the ignition.
I live in a great area that's pretty remote. Unfortunately, I relocated for work and the gun laws are strict. Therefore, I am stuck carrying a property just to store a previous collection.
Even if you have a mag drill you're going to get sick of drilling 1/2" steel pretty quickly, say nothing of 1". If you work with metal you probably have acetylene torches around, so you know how quickly a thief could get through even 1" steel firing up those.
Plenty of other good suggestions already, if it were me I'd probably go with 2x6 stud wall framed using nails and construction adhesive, then OSB, then expanded metal, 1/2 or 1" shims to space, more expanded metal, and fill void between with sandy concrete mix. This would immediately blunt any Sawzall blade, and demo/grinder wheels can't cut through the wood. Then contact cement drywall to that.
For monitoring, you can't beat a Sensaphone system. USA made, no monthly fees, web or phone based. Sensors for temperature, humidity, infrared (for fire or humans), power outage notification (with battery backup) and more. Great US based customer service. Obviously with the web based system you need a battery for your modem to receive notifications.