Drilling through back of safe

[timelinex]

My house is on a post tension slab, so I can't bolt the safe into the concrete (not safely and easily atleast). What I did to my last safe is drive 2 big bolts into the wall studs behind it.

My new safe is a much more "serious" safe though, amsec 7250hd. I'm sure I can drill through the back of this one as well with a little elbow grease....

But am I compromising the safes fire resistance by drilling through the concrete-like insulation in the back wall by drilling through it?

 

[larryh128]

If you have a good fit to the bolt it shouldn't be an issue.

 

[Punkur67]

You could fire caulk the hole or use firestop putty to seal around the bolt hole

 

[TxWelder35]

Before you go at it with a drill bit watch a couple YouTube vids on how to drill a hole in concrete and steel, it’s not actually as simple as one might think. Going to require 2 different bits. When you go through the steel make sure you are using a brand new metal bit and it will save you a lot of headache. High pressure low speed. Use speed setting 1 on your drill assuming your drilling a 3/8” hole.

if using a 3/8 lag predrill holes into the stud with a 1/4” bit.

fire caulk around it when you are done and should be g2g.

 

[K3RRY]

Before you go at it with a drill bit watch a couple YouTube vids on how to drill a hole in concrete and steel, it’s not actually as simple as one might think. Going to require 2 different bits. When you go through the steel make sure you are using a brand new metal bit and it will save you a lot of headache. High pressure low speed. Use speed setting 1 on your drill assuming your drilling a 3/8” hole.

if using a 3/8 lag predrill holes into the stud with a 1/4” bit.

fire caulk around it when you are done and should be g2g.

This and get backup bits just in case to make it easier and so you won’t need to drive to the hardware store multiple times

 

[diverdon]

I would not drill the back of the safe. I would order a Blanchard ground 1 inch steel plate the Same size as the safe. Drill and tap the plate to mount the safe. Epoxy plate to concrete mount safe. Use neverseize.

The grinding is optional.

 

[gnochi]

Alternative: mount the safe to a plate that is wider than the doorways to the room in both dimensions. For one, ain’t nobody going to be tipping the safe. For two, ain’t nobody going to be sliding the safe to the outside.

 

[Strykervet]

If you can't properly secure it to the floor, then my advice is to not bolt it. In some cases you'll ruin the warranty (which actually dictates how much it can be insured for, so be careful!) if you drill it at all. Others you can only do it in certain places and it has to be a certain dia. or less. I can't recall but it's small, maybe 3/8"? Really for running wires.

One option would be to weld a plate to the back with studs OR weld a SHORT section of log chain to it and lock it to the wall such it can't easily be reached or cut.

A security system will go a long ways towards preventing crooks from spending any quality time with your shit while you're away too. Doesn't need to be high speed, a motion detector and a siren loud enough to rock the neighbors out of a dead sleep is cheap and effective.

IF the crook is capable of removing your safe from it's location OR capable of breaching it quickly and effectively on the spot, then you're not gonna be able to stop that. Rare chance of that happening, risk isn't worth the reward.

And when you go to drill it, I think you're gonna be better served with high speed bits and high RPM's. Low RPM's and pressure cause the bit to bite and then it breaks it. That steel is HARD. I've drilled a few of these fuckers. I'd also start with a small hole first and then widen that. 1/8" is a good starter, fast, cheap and plentiful because yes, even if you don't break 'em you're gonna dull some beyond use. A little cutting oil will make this job a LOT easier too.

 

[TxWelder35]

If you can't properly secure it to the floor, then my advice is to not bolt it. In some cases you'll ruin the warranty (which actually dictates how much it can be insured for, so be careful!) if you drill it at all. Others you can only do it in certain places and it has to be a certain dia. or less. I can't recall but it's small, maybe 3/8"? Really for running wires.

One option would be to weld a plate to the back with studs OR weld a SHORT section of log chain to it and lock it to the wall such it can't easily be reached or cut.

A security system will go a long ways towards preventing crooks from spending any quality time with your shit while you're away too. Doesn't need to be high speed, a motion detector and a siren loud enough to rock the neighbors out of a dead sleep is cheap and effective.

IF the crook is capable of removing your safe from it's location OR capable of breaching it quickly and effectively on the spot, then you're not gonna be able to stop that. Rare chance of that happening, risk isn't worth the reward.

And when you go to drill it, I think you're gonna be better served with high speed bits and high RPM's. Low RPM's and pressure cause the bit to bite and then it breaks it. That steel is HARD. I've drilled a few of these fuckers. I'd also start with a small hole first and then widen that. 1/8" is a good starter, fast, cheap and plentiful because yes, even if you don't break 'em you're gonna dull some beyond use. A little cutting oil will make this job a LOT easier too.

so to avoid warranty issues you suggest welding to the safe. Brilliant.

I have yet to see a single safe that the back of it is made from hardened steel of any kind. It’s regular ol A36 steel. If it’s a high dollar safe it’s probably 1/4 wall. Cheaper ones are 14-11 guage. High pressure and low speed for a 3/8 bit. High speed burns out bits. Hence why you think you need a bunch of drill bits. You give me a brand new cobalt 3/8 drill bit and it’ll drill a lot of holes through thick steel. I’ve drilled dozens of holes in 3/4” plate with a single bit. Low speed, high pressure, cutting oil. That’s with a mag drill which gives many times more pressure than you can with a hand drill. You won’t ruin a bit with pressure without machinery on a 3/8” bit

 

[MK20]

If you can weld you can come up with almost infinite solutions. Go buy a cheap welder from harbor freight, practice and watch youtube videos. Then make anything you can think up.

 

[Missalot]

Drill the back and bolt it to the center of a wall stud. The stud will act as an insulator in the event of a fire until it burns through. If your fire lasts that long and gets that hot, your valuables will be metaphorically toast anyway. Just try to put it where is difficult to get leverage with a long pry bar or cut from the sides.

 

[addertooth]

Make a big "L" shaped plate, and bolt the safe to the bottom of the plate. Then secure the vertical part of the plate to the wall. NO voided warranties, no modifications to the safe, and secured to the wall.

 

[nikonNUT]

Brako (Exo-thermic) torch will make quick work of it and it will leave a pretty hole. I've used them to torch thru concrete walls to run air lines. 10000F will get it done! Not that I would....

 

[TriggerJerk!]

Clean the bottom and the floor. Then epoxy the safe to the floor.

 

[gnochi]

Brako (Exo-thermic) torch will make quick work of it and it will leave a pretty hole. I've used them to torch thru concrete walls to fun air lines. 10000F will get it done! Not that I would....

Ain’t nothing gonna protect from that. Thankfully, as long as you don’t have that kind of blowtorch sitting in your garage you should be fine. You just need to keep the kids honest, keep out a crowbar for a half hour, and make sure the sawzall isn’t sitting in the garage to give someone a 5 minute key.

 

[timelinex]

You guys have alot of good points and advice.

The room has sliding doors to the backyard, so welding something to make it not fit thru the doors isn't really a realistic option.

I think the safe is sufficiently heavy enough (~2500 lb empty) where bolts into the stud isn't adding much theft protection.

However, something that worries me is that I have tile baseboards on the bottom of the wall. So I won't be able to put the safe closer than 1/4" or so to the wall. So I am worried if I don't bolt it, it may be able to be rocked and tipped over. Not so much from thieves as it's the same 1/2" steel in the back as the sides. More so from kids. I am also worried that with the door open I will be at risk of the safe tipping.

 

[Missalot]

Bolt it to the wall. If it's that heavy, your greatest risk is getting the safe slid to where it can be tipped and then assaulted by a brut force entry or cutting, although cutting 1/2" steel without gas will take a while. Someone will have to be very determined to get into your safe. Make sure the kids don't speak to anyone about the safe or what's in it. You do have a monitored burglar alarm?

 

[gnochi]

You guys have alot of good points and advice.

The room has sliding doors to the backyard, so welding something to make it not fit thru the doors isn't really a realistic option.

I think the safe is sufficiently heavy enough (~2500 lb empty) where bolts into the stud isn't adding much theft protection.

However, something that worries me is that I have tile baseboards on the bottom of the wall. So I won't be able to put the safe closer than 1/4" or so to the wall. So I am worried if I don't bolt it, it may be able to be rocked and tipped over. Not so much from thieves as it's the same 1/2" steel in the back as the sides. More so from kids. I am also worried that with the door open I will be at risk of the safe tipping.

Yeah tipping is the problem. Without tools or help I can slide a 600lb safe a few feet if it’s not bolted in place. 3000lb fully loaded is doable with tools and a friend - I’ve had to heave around battery packs that weigh that much, and it sucks, but it’s possible.

The sliding doors to the backyard is also a problem, because someone can park in the backyard and use a cable winch to pull the safe wherever they want.

Assuming you want to be able to ever intentionally move the safe, I would consider either or both of:

1. Epoxying a steel plate with matching threaded holes to the slab, painting what you can see, putting a piece of moisture barrier over the plate, and bolting the safe to the plate. (Without the safe on it, the plate can be peeled up from the floor. It’s a pain but it’s possible.)
2. Screwing quality ~3/8” plywood behind the safe to every stud you can, drilling 8 or so matched holes in the back of the safe and the plywood, and using anchors to secure bolts from the inside.

 

[GH41]

"The sliding doors to the backyard is also a problem, because someone can park in the backyard and use a cable winch to pull the safe wherever they want"

Around here they are known to use wreckers to drag safes out. Bolts and walls are minor obstacles for a wrecker. I suspect in most cases the thieves knew what was in the safe beforehand.

 

[davsco]

You guys have alot of good points and advice.

The room has sliding doors to the backyard, so welding something to make it not fit thru the doors isn't really a realistic option.

I think the safe is sufficiently heavy enough (~2500 lb empty) where bolts into the stud isn't adding much theft protection.

However, something that worries me is that I have tile baseboards on the bottom of the wall. So I won't be able to put the safe closer than 1/4" or so to the wall. So I am worried if I don't bolt it, it may be able to be rocked and tipped over. Not so much from thieves as it's the same 1/2" steel in the back as the sides. More so from kids. I am also worried that with the door open I will be at risk of the safe tipping.

can you cut out the baseboard behind the safe? you do want that safe against the wall, so harder to put rope or chain behind/around it and pull it out/away. and actually if you remove the baseboard from the whole wall section, slide in the safe, then reinstall the baseboard tight to the safe, just something else to help avoid it being jimmied left and right, not that removing baseboard is hard.

 

[timelinex]

I'm starting to think that I am just going to put the safe in the garage. I was mostly against it since its not in my gun room and I know the garage is the worst place. But the more I measure the more im realizing this behemoth won't won't thru doors and won't make it thru the hallways correctly to get to where I want it. My garage is also not visible from the street. Then I can bolt it into the floor too, since the edge of my foundation is on the other side of the wall and I read I should be able to see where (and how deep!) the cables are for my post tension slab and avoid them. I also have the architectural plans for the foundation and slab.

Are there any negative consequences for rifles/guns sitting in a hot garage? It gets to 115 out here in AZ....

 

[BurnOut]

Drilling into a post-tension slab is no big deal at all. Anchor it to the floor with some 1/2" Tapcons and call it good.

 

[elwarpo]

Most fireproofing is sheertock,, which you will have behind the safe. the big issue is if the wall behind the sheetrock burns, the bolts will conduct heat into the safe. Fireproof insulation around the bolts inside the safe will help. The way the sheetrock works is to absorb the heat and use it to evaporate water. this will keep the temperature inside the safe up to 212F until there is no more water to evaporate.

 

[D̷e̷v̷i̷l̷D̷o̷c̷A̷Z̷]

My house is on a post tension slab, so I can't bolt the safe into the concrete (not safely and easily atleast). What I did to my last safe is drive 2 big bolts into the wall studs behind it.

My new safe is a much more "serious" safe though, amsec 7250hd. I'm sure I can drill through the back of this one as well with a little elbow grease....

But am I compromising the safes fire resistance by drilling through the concrete-like insulation in the back wall by drilling through it?

I didn’t read anything.

I too have had this issue. I was able to mount to concrete with Post Tension Slab. We had to pay a person to x-ray the floor. Mark the steel cables and mount the safes appropriately.

If you hit that cable you are fucked, you know that. If you go between the cables you are fine.

 

[timelinex]

Is there any concern with guns/rifles sitting out In the safe all summer? On the one hand it gets to 120 degrees here. On the other hand, outside of a few rains, it's always relatively dry. My garage is fairly decently insulated as well, so I dont think it gets hotter than outside.

 

[gnochi]

Is there any concern with guns/rifles sitting out In the safe all summer? On the one hand it gets to 120 degrees here. On the other hand, outside of a few rains, it's always relatively dry. My garage is fairly decently insulated as well, so I dont think it gets hotter than outside.

Nothing to worry about. Even the plastic bits should be fine until it’s over 250degF in the safe.

The humidity concern is solved by inside the safe being slightly hotter than outside the safe; that way, condensing moisture stays outside since there’s free air exchange.

 

[PostOak]

I didn’t read anything.

I too have had this issue. I was able to mount to concrete with Post Tension Slab. We had to pay a person to x-ray the floor. Mark the steel cables and mount the safes appropriately.

If you hit that cable you are fucked, you know that. If you go between the cables you are fine.

That’s the answer, there are company’s that can X-ray or GPR scan the slab very accurately. Once you know exactly where the cables are you can move the safe around them accordingly.

 

[davsco]

wth is a post tension slab? just a way to pour the slab thinner/less concrete/cheaper?

 

[gnochi]

wth is a post tension slab? just a way to pour the slab thinner/less concrete/cheaper?

Concrete is very strong against compressive loads, and flimsy against tensile loads, so most of the time when it’s used structurally, we use stretched (“tensioned”) steel to bias the concrete in the compressed direction. That way, it can withstand better tensile loading, but doesn’t have quite as much margin compressively.

There are two main ways this is done: pretensioning, and posttensioning. In the former, the rebar is stretched between stanchions, the concrete is poured, and when the concrete has cured - including to the rebar - the connections to the stanchions are cut, the rebar shrinks a bit, and the concrete is stressed. This is relatively cheap, but often develops serious corrosion issues within a few years.

Post tensioning, they cure the concrete with tubes in it, then run stretched cables through the tubes and anchor on the outside of the block to stress the concrete, and pack the tubes full of grout to prevent corrosion. This is more expensive, but lasts essentially forever.

Finally, sometimes they just pour concrete and your foundation cracks the following winter. This is dirt cheap and is the construction equivalent of a StackOn chinesium gun cabinet.

 

[2aBaC̶a̶]

I wonder if you could have it Xrayed to find a good place to drill the slab. They do it in commercial construction.

 

[GH41]

wth is a post tension slab? just a way to pour the slab thinner/less concrete/cheaper?

Usually done where soil conditions are not ideal. Here are some answers> https://buyersask.com/articles-of-i...ab is,reinforcement and helps reduce cracking.

 

[darrenk75b]

I'm a structural engineer who designs post-tensioned concrete for a living.

What the others have said is true. Hire someone to GPR scan the floor (less expensive than x-ray) to locate the cables. Stay 6" clear of any located cable, and you'll be fine with whatever anchor you choose.

It's likely anyway that your cables are deep enough below the surface to not cause a problem anyway with the depth of most anchors. But, the scanning is a good precaution.

 

[timelinex]

I'm a structural engineer who designs post-tensioned concrete for a living.

What the others have said is true. Hire someone to GPR scan the floor (less expensive than x-ray) to locate the cables. Stay 6" clear of any located cable, and you'll be fine with whatever anchor you choose.

It's likely anyway that your cables are deep enough below the surface to not cause a problem anyway with the depth of most anchors. But, the scanning is a good precaution.

I have the foundation plans for the house but I have read enough online to know not to trust them.

Luckily the place I'm placing the safe is on the other side of the wall of where the foundation ends. So I dug a foot down next to my house and using a magnet found where the Tensors are. They are slightly over 3" below my ground level. So I will just use bolts that don't require more than 2.5" of drilling and call it a day.

I've always used wedge anchors in concrete but read the special bolts like Tapcon's are actually just as good. Is that true? That would be ideal as I could remove them later without needing to leave anything in the concrete.

 

[GH41]

I wouldn't use wedge anchors or Tapcon bolts anywhere near the edge of a slab. Against the exterior wall I would glue in 5/8" threaded rod at least 6" deep. Darrenk75bb can probably tell us what the minimum depth should be.

 

[darrenk75b]

How big of holes are in your safe? The concrete screws (Tapcon and similar) have such aggressive threads that you usually have to downsize the bolt diameter in order to get them through a hole unless the hole is specifically sized for them.

We use screw anchors all the time, especially in near-edge conditions like this. They are nice in that they can be removed easily. You may get better anchorage capacity from an epoxies threaded rod like GH41 mentions.

You tell me the hole size and I'll run some numbers for you, then you can decide the route you want to take.

 

[timelinex]

How big of holes are in your safe? The concrete screws (Tapcon and similar) have such aggressive threads that you usually have to downsize the bolt diameter in order to get them through a hole unless the hole is specifically sized for them.

We use screw anchors all the time, especially in near-edge conditions like this. They are nice in that they can be removed easily. You may get better anchorage capacity from an epoxies threaded rod like GH41 mentions.

You tell me the hole size and I'll run some numbers for you, then you can decide the route you want to take.

It is going to be for the pre-drilled anchor holes in an Amsec 7250 HD. I don't have it in front of me and I don't see the dimensions online. Although I do not think it matters much as the hole is at minimum 3/8 and I can use washers to account for smaller screws. I would like the hole to be less than 3" deep, so I think I can get at maximum a 3/8 Tapcon. But I am thinking I can do 5/16 tapcon's and with a minimum embodiment of 1.75", that requires only a 2.25" hole and puts me in very safe territory. I think even the 5/16 one's provide 2000+ of pullout strength for each bolt which is more than enough, I think? Any comments?

As far as there being issues being too close to the edge... It seems like even the 3/8 has a "critical edge distance" of 4 inches. Just my Garage wall thickness is 8" or so. (edge of foundation is with outside edge of the wall). So I don't think I should have any issues?

 

[timelinex]

How big of holes are in your safe? The concrete screws (Tapcon and similar) have such aggressive threads that you usually have to downsize the bolt diameter in order to get them through a hole unless the hole is specifically sized for them.

We use screw anchors all the time, especially in near-edge conditions like this. They are nice in that they can be removed easily. You may get better anchorage capacity from an epoxies threaded rod like GH41 mentions.

You tell me the hole size and I'll run some numbers for you, then you can decide the route you want to take.

OK guys, the time is coming up and my wife is not too happy about me drilling into the concrete. I would be most confident if I didn't have to drill more than 1.25" into the concrete. That gives me alot of room past my measured cable/tendon depth.

Looking at 3/8" diameter minimum embedment values, it is ~1.75" for 3/8 Tapcons and 1.5" for 3/8 Red Head wedge anchors. The hole needs to be 0.25" deeper than those values. So its 2" and 1.75".

Anyone have any advice or experience with using a Tapcon or Wedge at less than minimum embedment values? Is there still a good amount of bite? The data sheets show that the difference between 1.5" and 3" embedment for the wedge is 1,600 vs 3400 lb tension strength, so about half. Is it reasonable to expect atleast half of the 1,600 at only 1" embedment? If so, 800LB x 4 bolts = 3,200LB which sounds reasonable enough!

If I was to drill a 1.25" hole, would I be better off going with the Tapcon or the Red Head Wedge? I know 1" embedment is closer to the Red Head's minimum, but not sure if the wedge is more sensitive to depth than a screw like the Tapcon.

Thanks

 

[gnochi]

OK guys, the time is coming up and my wife is not too happy about me drilling into the concrete. I would be most confident if I didn't have to drill more than 1.25" into the concrete. That gives me alot of room past my measured cable/tendon depth.

Looking at 3/8" diameter minimum embedment values, it is ~1.75" for 3/8 Tapcons and 1.5" for 3/8 Red Head wedge anchors. The hole needs to be 0.25" deeper than those values. So its 2" and 1.75".

Anyone have any advice or experience with using a Tapcon or Wedge at less than minimum embedment values? Is there still a good amount of bite? The data sheets show that the difference between 1.5" and 3" embedment for the wedge is 1,600 vs 3400 lb tension strength, so about half. Is it reasonable to expect atleast half of the 1,600 at only 1" embedment? If so, 800LB x 4 bolts = 3,200LB which sounds reasonable enough!

If I was to drill a 1.25" hole, would I be better off going with the Tapcon or the Red Head Wedge? I know 1" embedment is closer to the Red Head's minimum, but not sure if the wedge is more sensitive to depth than a screw like the Tapcon.

Thanks

The purpose of the minimum embedment is to set a value such that the overwhelming majority of the time, neither a shear nor a tensile load will damage the concrete - the bolt will fail first, and can be replaced.

I strongly recommend keeping above those values, because repairing a foundation is not worth half an inch of additional drilling when you still have lots of clearance to the cables.

As another alternative, you could epoxy a few of these in place (after thoroughly cleaning the concrete, they’ll stay forever) and drop the safe onto them: https://www.mcmaster.com/97590A606

 

[timelinex]

The purpose of the minimum embedment is to set a value such that the overwhelming majority of the time, neither a shear nor a tensile load will damage the concrete - the bolt will fail first, and can be replaced.

I strongly recommend keeping above those values, because repairing a foundation is not worth half an inch of additional drilling when you still have lots of clearance to the cables.

As another alternative, you could epoxy a few of these in place (after thoroughly cleaning the concrete, they’ll stay forever) and drop the safe onto them: https://www.mcmaster.com/97590A606

Hmmmm, thats interesting. Thanks for the lesson on minimum embedment! I did not realize that.

 

[timelinex]

I've noticed there are 2 different type of concrete drill bits avaiable at Home Depot. There are ones for concrete and ones for concrete and rebar.

I bought the concrete/rebar one since it was barely more expensive and figured it will be more sturdy. Thinking about it now though, should I use the "weaker" one, so that if the worst case scenario happens and I run into a tendon, the drill bit won't be as effective against it and I will more likely notice hitting it.

 

[gnochi]

I've noticed there are 2 different type of concrete drill bits avaiable at Home Depot. There are ones for concrete and ones for concrete and rebar.

I bought the concrete/rebar one since it was barely more expensive and figured it will be more sturdy. Thinking about it now though, should I use the "weaker" one, so that if the worst case scenario happens and I run into a tendon, the drill bit won't be as effective against it and I will more likely notice hitting it.

The rebar bit is made to last a bit longer when going through rebar. Either way, you’re fucked if you nick the cable - I highly recommend getting either a drill bit stop, or a tube that fits over the bit that you cut so it bottoms out when you’re at the right drill depth.

Did you get a wet drill bit or a dry drill bit?

Finally, it should be pretty cheap to get someone to stop by for a few minutes with a ground-penetrating radar to mark any cables/anything else relevant. Even with precautions that won’t hurt!

 

[timelinex]

The rebar bit is made to last a bit longer when going through rebar. Either way, you’re fucked if you nick the cable - I highly recommend getting either a drill bit stop, or a tube that fits over the bit that you cut so it bottoms out when you’re at the right drill depth.

Did you get a wet drill bit or a dry drill bit?

Finally, it should be pretty cheap to get someone to stop by for a few minutes with a ground-penetrating radar to mark any cables/anything else relevant. Even with precautions that won’t hurt!

I would happily pay someone a small fee to stop by and mark things. But a quick preliminary search made me think it's not 'cheap' and likely 500+ just to get anyone out.

If anyone knows someone in the Phx area with the equipment, I would happily do it right.

 

[timelinex]

Well, it's all done and house is still in tact! Unfortunately I could only do about 2 inches and not the recommended 2.5". Since I added a wood frame underneath like recommended, the screws were just not long enough in 3/8" to do any more than 2". This thing is going NOWHERE though. I was surprised that even before the anchors, the safe is so heavy that it wouldn't start tipping even if you open the door and start hanging on the door a bit.

Pro tip: the hammer drill function on the "powerful" dewalt cordless drill is shit compared to a purpose built rotary hammer drill. I spent 30+ minutes on one hole, and barely finished it with sore arms, elbows and back. Then I bought a cordless dewalt rotary hammer drill and the difference is insane. Each hole took 30 seconds and it drilled thru the concrete like butter. It was almost fun. I knew the rotary is supposed to be better, but not like this. Don't waste your time and effort with standard hammer drills fellas.

 

[Ozarkcop]

If your just worried they can tip it over bolt some angle iron to the wall stud above the safe. If they can move a 2500 safe during a burglary there isn’t much you are going to do to stop them though.