Securing a safe to a post-tensioned slab - DIY

[79camaro]

Well, I am having more problems figuring out how/if I should bolt down the safe than when I was trying to decide WHICH safe to get! LOL!

I'm not sure I will build a raised slab in my closet, that might work great in the garage....but not in a closet. At the same time, I am having great doubts about drilling (even 3/4") into the slab....so I am leaning towards the 4x4s epoxied onto the floor and using lag bolts to secure the safe to the 4x4s

I plan on getting a security system, so I just want to slow down the burglar. Odds are that IF my house is broken into, it will NOT be a pro, but rather a meth head that is just looking for quick "grab and run" items. So, I don't believe he would even mess with the safe, and if he did, he would do minimal damage to it and the police get there while he's trying to figure out which kitchen knife to use on the safe!

[John Browning]

Incorrect my friend. My tract home has NO pre or post tensioning. My driveway is the only slab that is post tensioned and there are only two arched cables for the entire slab.

It makes no sense to PT a driveway, but anything is possible. Unless your driveway is about 6 feet long it is also way out of code.

it is also important to note that you must READ and stamped noticed of PT concrete. In some cases it ONLY refers to the garage slab and not the house slab. You may be able to get information from the builder (based on age of structure). Check with your local building authority (city. county, etc) as they issued permits to the builder. As far as inspections of the concrete are concerned.......I have NEVER seen any inspector at each tract home inspecting concrete forms, placement, or finish work, including PT.

Ok, now I know you're a troll. Inspectors are all over foundation work, and for PT jobs are usually on site. This is California. Everything gets inspected 10000 times more than is needed. Garage slabs and house slabs should also be one in the same if they are attached, or else you'd have major problems as they settle separately. I'm not surprised you don't know this. What state are you licensed as a contractor in?

I was in a safe shop yesterday and the owner of the shop told me that you can just drill and that the cable is so tough that the drill will just go to one side of it since the drill won't be able to get through. And if this happens, just move the safe a little bit to move where the hole will be over and keep on drilling.

Then he quoted me $1300 for a 14 gun Amsec fire gunsafe.

These cables are coated in a red plastic. If you started seeing red plastic, you might be able to stop before you cause serious damage. However, remember that the cables are under huge amounts of tension. If you have ever tried to cut rope or cable that is under tension, you know how quickly it wants to fly apart. The owner of the safe shop has a whole lot less to lose by giving bad advice than you do in following it.

[John Browning]

SCOBUN,

Regarding the straps in step #9 of your sticky, where did you get them and do you have pictures of how exactly they go on the safe?

They came as part of the pallet of one of the safes I bought. On your cheaper safes there will be very little on the bottom and you can just use them basically as one big strap between anchor holes. It acts somewhat like one big washer and is great because the bottom of most gun safes would rip out long before the bolts give.

Well, I am having more problems figuring out how/if I should bolt down the safe than when I was trying to decide WHICH safe to get! LOL!

I'm not sure I will build a raised slab in my closet, that might work great in the garage....but not in a closet. At the same time, I am having great doubts about drilling (even 3/4") into the slab....so I am leaning towards the 4x4s epoxied onto the floor and using lag bolts to secure the safe to the 4x4s

I plan on getting a security system, so I just want to slow down the burglar. Odds are that IF my house is broken into, it will NOT be a pro, but rather a meth head that is just looking for quick "grab and run" items. So, I don't believe he would even mess with the safe, and if he did, he would do minimal damage to it and the police get there while he's trying to figure out which kitchen knife to use on the safe!

If I were putting a safe in a closet, I'd lag it to floor joists if they are there. If it is concrete, I'd probably build a false wall and try to conceal it. I definitely wouldn't put a raised slab in a closet.

[Beauhooligan]

If I were putting a safe in a closet, I'd lag it to floor joists if they are there. If it is concrete, I'd probably build a false wall and try to conceal it. I definitely wouldn't put a raised slab in a closet.

I have no knowledge about construction and just drilled and put anchors for 3/8ths high grade bolts to secure my three safes to the slab foundation of this house I own, built in '75. Now I am moving into my parents old house, built in the '50s, with a wooden joist foundation. This is a great house in one of the best neighborhoods in town. I don't even know about how the flooring and foundation will stand up to the weight of my big Champion safe, or even the two smaller Browning boxes. I'm thinking of hiring a construction engineer to take a look at the house and the details of the safes; weight loaded and footprint; and give me advice. I like putting safes in closets as it makes the safe harder to attack, and more costly to the crooks in terms of noise and time; seven years as a working cop gives me that perspective. Crooks don't like to make a great amount of noise, which increases the chance of detection, and time spent on the job is a matter of life and death. I'll bolt the safes to both floor joists and wall studs. That, combined with a really good alarm system, solid steel bars on the windows and gates on the doors, and a smiling black Chow, just might do the trick. But, I'm going to spend the money on the service of a construction engineer before I do anything, not even buy materials.

[baaadmoon]

PT Slab Safe install

Excellent info. Thanks so much

[beavis11]

Another option for a post tension slab

Redhead RX-38 drop-in anchors. Only need to drill 3/4" deep. You have a better chance of winning the lottery while getting struck by lighting then you do of hitting and severing a PT cable drilling a 1/2" diameter hole 3/4" deep with a masonry bit.

1,571lbs-1,987lbs of tension strength per anchor. Shear strength of 2,295lbs-2,903lbs per anchor.

[AdiosKali]

Great info! I need to find out if the slab in my new house is PT. Never would have thought anything about it and drilled away

[CWL]

Great post and very timely! My house has PT slab flooring and I've been trying to figure out a cheap but effective way securing my safe in the garage.

Never thought it'd be that easy to add a pad on top of the slab!

Thanks!

[SJgunguy24]

Well, I am having more problems figuring out how/if I should bolt down the safe than when I was trying to decide WHICH safe to get! LOL!

I'm not sure I will build a raised slab in my closet, that might work great in the garage....but not in a closet. At the same time, I am having great doubts about drilling (even 3/4") into the slab....so I am leaning towards the 4x4s epoxied onto the floor and using lag bolts to secure the safe to the 4x4s

I plan on getting a security system, so I just want to slow down the burglar. Odds are that IF my house is broken into, it will NOT be a pro, but rather a meth head that is just looking for quick "grab and run" items. So, I don't believe he would even mess with the safe, and if he did, he would do minimal damage to it and the police get there while he's trying to figure out which kitchen knife to use on the safe!

I wouldn't epoxy 4X4s to the floor. Go with the drop in anchors into the pt slab. Just make sure you only go in 3/4" and you have the proper set tool that leaves the imprint on the face of the drop in anchor when it's set properly.
I've drilled thousands of drop in anchors, and suspended hundreds of pieces of HVAC equipment from those anchors. The key is you cannot drill two unless they are at least 10 times the diameter of the anchor apart.from each other.

[John Browning]

I wouldn't epoxy 4X4s to the floor. Go with the drop in anchors into the pt slab. Just make sure you only go in 3/4" and you have the proper set tool that leaves the imprint on the face of the drop in anchor when it's set properly.
I've drilled thousands of drop in anchors, and suspended hundreds of pieces of HVAC equipment from those anchors. The key is you cannot drill two unless they are at least 10 times the diameter of the anchor apart.from each other.

One other thing to check is how drilling a PT slab impacts your home-owners insurance.

[1911Luvr]

Thanks to this thread I was able to make a very solid base for my safe on top of my post-tensioned slab. I scored the existing slab using the OP's method, created a form that perfectly fit the upper edge of the existing slab line, cut and tied rebar to the rebar spacers, painted on the concrete adhesive and poured the high-strength concrete all in about a day and a half. The hardest part was loading the 12 bags of concrete into the truck at Lowes!

Before:


After:

[Vz58man]

Very cool thread. I trust Ops knowledge on the matter. Seems like a safe and well done venture. What are your opinions on securing closet safes?

[John Browning]

Very cool thread. I trust Ops knowledge on the matter. Seems like a safe and well done venture. What are your opinions on securing closet safes?

I would only put a safe somewhere you can secure it to the slab, so for that reason closets are out for me. If you have a floor with joists in it, then lagging it to a joist will probably do as well as you could.

[KrisDSA]

Thank you for this DIY.

[sixoclockhold]

drilling a two inch deep hole in any concrete is going to snap a tendon as often as airliners having a head on. Use epoxy to secure the anchors, not redheads.

Too much rebar, too many dobies (they create a void). Mesh pulled up to the middle of the pour would have been ten times better.

But, a good training project for sure.

I guess I'm with stupid,

Only 40 years fixing stuff and I wonder how many here have actually hit rebar drilling concrete?

http://www.ptia.org.au/Documents/PTIA_GN06V2_PostCutHoles%20through%20Post%20Tensioned%20Slabs_Dec14.pdf

http://www.amsyscoinc.com/2010/01/29/material-properties-of-post-tension-strands/

Tendons are about 4 times as strong as rebar and consist of 7 strands so damaging all seven, well that's kinda like that head on jet airliner deal if you're using a cheap Home Depot carbide bit and a regular drill. You ain't getting thru it, really, do you even lift?

Most engineers never had a pair of knee pads on in their lives but I can assure you they can design stuff that can't be washed or used properly.

Drill baby Drill