I have a 12'x12' upstairs bedroom. Can a 2000 lbs safe be placed in that room? The dimensions would be the same size as a queen size bed (60"x80").

Can you supply the math in your answer.

Thank you in advance


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    1) The size of the room doesn't matter, but rather its construction. 2) You have a safe that's 5 feet on one side and almost 7 feet on the other? – mike65535 Feb 7 '19 at 12:57

If we assume your room was built to minimum standards from the IBC 2015, for example the live load table #1607.1 from here which lists habitable sleeping areas to support 30 pounds per square foot minimum:

(80" x 60" ) /144" = 33.33333 square feet.
so 30 pounds spread over 33.3333 square feet would be 1,000 pounds.

Depends on how over the minimum the original construction was designed to, but would need to be at least 60 PSF to for a 2,000 pounds load concentrated over a 60"x80" area.

Over a 12' span, you would need to have at least 2x8s installed at 16" on center to support 60 PSF.

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  • The home in question is in Orange County California. I believe most floor joist are 2"x10" 16" on center. What is the maximum span I can go to hold the 2000 pounds. – Danny O Feb 6 '19 at 22:15

The Code requires a minimum live load and dead load for the ENTIRE floor area, not just where the “bed” is located. The load is not evenly distributed throughout the room, but rather on a portion of the room.

The new Code requires 40 lbs. per square foot, but if your house is more than 3 years old, 30 psf is a better factor to use.

Therefore, a 12’ x 12’ room with a live load of 30 psf will support 4,320 lbs for the ENTIRE room. Now, there are a couple issues: 1) distribution of load and failure of joists, 2) failure of sheathing, 3) cracked ceiling below room

1) Depending on the species and grade of your lumber, joists could span considerably further than 12’ and still support your safe and 3 of your buddies standing around examining your guns, money, whatever...

Assuming the safe is resting on joists in the 80” direction, that means it’s resting on 80”/12=6’-8” or 5 joists at 16” oc. Total load supported by 5 joists at 16” oc is 6’-8” x 12’ long x 30 psf = 2,400 lbs.

Assuming the safe is resting on joists in the 60” direction, then 60”/12”=5’ or 3.75 joists, say 4 joists. Therefore, total load supported by 4 joists is : 5’ x 12’ long x 30 psf = 1,800 lbs.

We know that loads are transferred to adjacent joists too. Generally we assume a floor load will transfer to 1 adjacent joist on each side of the load. However, in your case, I’d assume just 1/2 joist in each direction, because we don’t know the species or grade. Therefore, 4 joists would become 5 joists and 5 supporting joists would become 6 joists.

2) Assuming there is a floor to your safe, you don’t have a problem with a wall of your safe resting between the floor joists. If not, then there are other issues.

3) Floor joists deflect significantly before they fail. Because you indicated this room is on the second floor, I’m assuming you have gypsum board on the bottom of your floor joists. To keep the gypsum board from cracking, I’m using L/360. (Very stiff...not much deflection.)

You also ask “What is the maximum span for 2x10’s at 16” oc in order to support 2,000 lbs.?” So, assuming SPF lumber with a grade of #2 & better, I’d use 16’ as a maximum span, which will allow a live load of 30 psf, plus 10 psf dead load (over balance of span) and a maximum deflection of L/360 over 5 floor joists.

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