Maximum gun safe weight on flooring


May 18, 2005, 04:08 PM
I would like to purchase a gun safe and place it on oak hardwood floors on the first floor of my home. My home is built on a crawl space (wood joist, 16"o/c, 2x10). Does anyone know how large a safe I can buy without damaging the floor? If additional support is required, what is recommended?

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Greg L
May 18, 2005, 04:30 PM
I'm not sure about the weight limit but if it is over a crawl space you could just build up a stack (or four - one in each corner) of concrete blocks under the area where the safe would go.

May 18, 2005, 05:01 PM
wood joist, 16"o/c, 5x10
As long as the safe is against a wall were the joists bear for support it is pretty unlikely you can make it heavy enough to have a problem. Placing it at the mid span of the joists could be a problem even if the safe is empty.
Check the dimensions again, and then find out what the span (support to support distance) of eh joists.
Most hoses are designed for a 40 pound per square foot live load (30 PSF in bedrooms) plus a 10 PSF dead load on the entire floor. A spot load can exceed these numbers, but a permanent spot load like a safe should be near the end of a joist and the bearing support.

May 18, 2005, 05:05 PM
You will have to expect some sagging of the area over time if the safe is very heavy.
Put in some support columns and/or concrete as suggested above. Even with added support, you prob will have some depression of the oak flooring eventually.

May 18, 2005, 05:11 PM
Unless somebody here happens to be an engineer, I would consult the phonebook. I have seen safes in the thousand pound range sitting on pier and beam floors, but it is really impossible to say what your floor will support without more info than either of us know how to gather.

May 18, 2005, 06:12 PM
Just my opinion (I'm a molecular biologist, not an engineer darn it! :D ), I'd treat the safe the same way one would treat a King sized water bed or large (> 100 gallon) aquarium. Spread the weight across as many floor joists as possible, keep it close to load bearing walls below it, or the steel I-beams that support the floor joists of your home has them. Consulting a structural engineer would be a good idea.

Remember: When in doubt, don't do it.

The Bear
May 19, 2005, 02:37 AM
Brickeyee is absolutely correct. I'm a civil engineer and contractor. If you figure a heavy steel gun safe weighs around 1000 pounds (a 'kip' to engineers) and it's 4' wide and 3' deep you have 12 square feet divided into 1000 pounds or 83 pounds per SF. That's DOUBLE the design live load!! You can't use the additional dead load of 10 psf for help because that's the weight of the floor structure and it's real.

Here's my advice for what's worth:
- Keep the safe close next to a wall, preferably a bearing wall if possible.
- See if you can add support under the safe. If the safe will be permanent have an local engineer suggest a support system that won't look too stupid. Expect to pay him/her $300 to 500 depending on where you live for this service.
- The absolute worst possible place for the safe is at the mid-span of the floor joists so make damn sure you understand how your floors are built. You may inadvertently put the safe next to a wall that is at the midspan of the floor. Anything you can do to shorten the length of the floor joists with supports will help a lot.
- You will probably be safe with this setup but you may be at the absolute limits of the design for safety factors. I can't recommend this without additional support.
- Don't let anyone sleep under this safe downstairs until the floor is supported.
- There is no way for anyone to accurately evaluate your floors without knowing the length and spacing of the joints, the type and grade of the wood and the type and load capacity of the plywood sub floors. The weight of the safe is critical- it must be known or closely estimated.

Rule of thumb- if your floors start sagging (deflecting) and you can see it or feel it you have a problem!

Hope this helps! BTW- my Liberty safe sits on 5" of concrete in my garage! Both my safe and I are happy!!

Taurus 66
May 19, 2005, 04:06 AM
Do Not set safe bottom center over one beam, rather set the safe evenly covering over two beams, for added support. This displaces (more evenly distributes) the weight.

Browns Fan
May 19, 2005, 08:27 AM
"BTW- my Liberty safe sits on 5" of concrete in my garage! Both my safe and I are happy!!"

In your garage? Arent you concerned about the possiblity of your guns or even you safe rusting?

Highland Ranger
May 19, 2005, 08:33 AM
Also keep in mind that oak floors move (expand and contract) - putting something ths heavy in one spot may in some way inhibit that seasonal movement and cause the floor to do bad things (crack, warp etc.)

(A lot depends on how much swing you get in your humidity -> where I live we can go from 20-100, pretty big swing. Cheaply made furniture doesn't last long in the highlands . . . . )

May 19, 2005, 01:42 PM
Well, I just happen to be a civil engineer, and have done this and helped others with it. Generally speaking, all of the previous posts are correct. Wooden house floors are rated for around 40 PSF. The size of the safe is not the only consideration. It is the weight AND the footprint. A 25" x 30" safe can that weighs 200# is fine. The same safe that weighs 1200# is not. That being said, I recommend that you check your floor joists for location and supports, and set the safe across AT LEAST two joists, rather than centering one joist. You should also place the safe as close as possible to joist supports. Against an outside wall is almost always good, but inside walls may or may not be supported. You should also put down a piece of plywood under the safe, a bit larger than the safe is, if it's going to sit on carpet, etc., to keep it from sinking into the carpet. This also reduces the PSF. Finally, I would use a 4x4 underneath all the supporting joists, with a screw-type house jack and flat concrete or heavy steel pad supporting that. If your safe is backed against a supported wall, it will be typically be facing the direction that the joists run. Place the 4x4 across the joists under the safe, near the front (door). Screw the jack up until the safe is level. This can be adjusted in the future as needed.

Keep in mind that I am not judging whether this method or your execution of it is safe in your situation - I am just offering some tips for this type of installation.

May 19, 2005, 03:43 PM
I have a PE for what it matters.

May 19, 2005, 06:24 PM
In answer to "Browns Fan" question about guns rusting if the safe is in a garage. Perhaps, if no steps are taken to prevent it. Rust is caused by condensation on guns. My safe is in a notoriously humid basement. My guns do not rust. The answer? A device called a "Goldenrod," available at many shooting supply outlets, in several sizes. It plugs in and heats up, keeping the inside of the gun safe / cabinet just a bit warmer than the outside air. Result: no condensation, no rust. It only draws a few watts of electricity; problem solved.

The Bear
May 19, 2005, 07:32 PM
Brickeyee- I could tell you were a PE because no one but an engineer (or an architect on a good day!) knows, or cares, about the difference between live and dead loads! Someone asked for some engineering help so I thought I'd throw my 2 cents in.

Some guys have posted that spreading the load over two joists will solve the problem. I don't necessarily agree. It's always a good idea but it gives the impression you can seriously overload a floor system if you just pick up two joints. Better than nothing but when in doubt have it checked!

Just what the world needs- someone getting killed by guns while they're locked up in his safe!

Browns Fan- Goldenrod is a great piece of hardware. I haven't had any humidity problems to date plus I keep Break Free CLP on everything.

Guy B. Meredith
May 21, 2005, 03:12 AM
Okay, I am not an engneer and need some help as I, too, plan to purchase a safe and am trying to figure a location. I had been considering the closet in my home office/third bedroom. You also have me worried because I have a California king water bed on a raised floor.

You say the live load limit is 40 psf/30psf, but a 200 pound person can stand on one square foot without a problem. What is the exact criteria for the load?

May 21, 2005, 05:14 AM
How much floor space does a 200 pound person occupy?
Unless you plan on packing the room as tight as you can get those folks, each will probably be at least 5 square feet (partly in jest).
Heavy people do cause more deflection. How many times have you heard the china cabinet rattle slightly when he wals buy, butno sound when she wals buy? (assuming average weights).
Residential construction has pretty large margins. The joists are sized for the entire floor to be at 50 PSF dead+live. Even a 6 inch thick water bed is only around 30 PSF (not including occupants).
Cast iron radiators are probably the heaviest point load in houses, and in many cases of they are parallel to the floor joists you can see large sags.
Placing the safe near the joist end and spreading over as many joists as possible should cover all but the heaviest safes. While the point load is over the average 40-50 PSF load, unless you load up the rest of the joist you are unlikely to have a problem.

Brett Bellmore
May 21, 2005, 10:13 AM
45crittergitter nailed it. The only thing I can add is, if it's a particularly heavy safe, keep in mind that you've got to get it across the floor to it's final destination, too. Plan on laying it flat, and sliding it, so that the weight is spread out widely until it's in place. And only then tipping it up, onto that piece of plywood.

May 21, 2005, 11:12 AM

I'm not an engineer, but I do sell safes, heavy safes. The lightest standard home use gun safe I carry weighs 1100 lbs. And yes, that weight is frequently a major concern for people who do not wish to locate their new safe either in the basement, or in the garage.

All of the suggestions involving a floor jack, shoring, piers, etc. are correct. It's also possible, depending upon your home's decor, to place an 1/8" steel plate under the carpet & spread the load in that fashion. Keep in mind that the weight of the plate itself has to be factored in AND you still can't place the safe in mid-span.

If you wish to put your safe in the basement, there are a couple of other things to keep in mind. However, if you've got an RSC, the following is just for entertainment value, as RCS's are lightweights. Inspect and support your stair stringers. Even though good stair walkers will spread the load over 2 to 4 steps, the stringers are the weak point. Make absolutely sure you have the necessary manuvering room to break the load back at the head of the stairs & turn, if needed, at the bottom. Check your overhead clearences first, usually this is only a concern with 72" tall units, but we've encountered some fairly strange construction in the past.


May 22, 2005, 01:39 PM
"to place an 1/8" steel plate under the carpet & spread the load in that fashion."

This will not spread much of anything. A 1/8 plate has little stiffness to speak of perpendicular to the face.
If you go over a couple hundred pounds as a permanent point load you probably need some decent reinforcement of the structure. Even with the structural support, you will likely exceed the allowable crush load on the joist. The bearing area is typically only about 1.5 X 1.5 inches = 2.25 in^2. With four supports and this area an 1100 pound safe is creating 122 PSI on the bearing surface. When combined with the existing loads from the structure you are going to be well above the allowable crush limit.
The wood itself will slowly crush, and depending on what structural loads are also present could cause significant structural damage.

May 22, 2005, 02:32 PM
Well, this is one advantage of living in AZ. Pretty much all houses sit on a concrete pad, and most are 1 story (though with new construction multi-story is getting more common). So long as I keep it on the ground floor (not tough in my 1 story house) I have a thick concrete pad to support any size safe I would want.

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