I'll admit I don't get how to compute how much my floor can hold, and probably wouldn't trust my own math, even if I came up with the right answer.

I'm looking to purchase a recording booth. I do voice-over work. There's one for sale in my area that the manufacturer says weighs 2015 lbs for the base model. This one has some extras, so lets call it 2100, or maybe even 2150. I weigh 220, so the package would be in the vicinity of 2400, to be safe. The booth has a footprint of 6' x 6'. The home is in the Chicago area, built in 1988.

The room it would be going in is an exterior room, at the first floor back corner of the house. The first floor is over a basement. THe floor joists are 2 x 12s, I believe; I thought a 2x12 was 11 1/4 high/wide. These are either 11" exactly, or some are even closer to 10 7/8", so I'm a little confused about that. I haven't found one that was 11 1/4". Anyway, if I'm measuring correctly, then right under the interior wall perpendicular to the back wall of the house is a laminated joist made of 2 2x12s with a 1/2" steel plate in the middle. The booth would be resting in the room in the interior corner, where one wall is exterior and the other rests over the laminated joist. That laminated joist runs approx 17' where it ties into the I-beam that runs the width of the middle of the house.

Will my floor safely hold the weight of the booth?

To answer a couple of the questions raised:

Why is the booth so heavy? Because isolation requires mass. If you want to keep sound out, the walls have to have mass. This particular model of booth (manufactured by a leader in the industry) has a double-wall design for increased isolation from outside noise. Each 4' x 7.5' section is two slabs of 5/8" MDF with an air gap in the middle. The windows (2) each include four slabs of 1/4" tempered glass. It adds up.

Is there an option for placing the booth in the basement? No, because the only place for it in the basement is just feet from the furnaces, which defeats the purpose.

laminated beam

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    Hello, and welcome to Home Improvement. Although you've done a good job asking the question, and have an answer, this really can't be safely answered by anyone except for an on-site structural engineer. And, you should probably take our tour so you'll know you'll know the details of contributing here. – Daniel Griscom Aug 17 at 22:18
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    I’m voting to close this question because answering it should require an on-site structural engineer. – Daniel Griscom Aug 17 at 22:19
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    I am not an engineer. A quick check on line at a Boise Cascade website reveals that standard design criteria is 30lbs/sqft for bedrooms and 40lbs/sqft for general residential space. To be realistic you will likely continue to add more items to the booth increasing the weight even more. – mikes Aug 17 at 23:03
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    Why is this recording booth so heavy to begin with? O.o – ThreePhaseEel Aug 17 at 23:45
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    A king water bed weighs 2000-2500 pounds. That is a frame of reference for what a bedroom is asked to support. The fact that you are not placing the load in the center of a long span is a positive too. – Kris Aug 18 at 13:22

I popped off a google search on how many pounds per square foot is typical of a human. The answer in the search results (last entry in the linked pdf) provided 2.5 to 3.5 pounds per square inch, which translates to 360 to 504 pounds per square foot.

If one stands on one leg, the figures would be double, which is rather substantial.

Your booth at 2400 pounds over 36 square feet converts to 92 pounds per square foot. This would lead one to believe that the even distribution of the weight over the floor would be less than that of many humans in the same area.

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  • @AlaskaMan yeah, lifting a foot causes an equal and opposite reaction, etc. etc. ... lol – jsotola Aug 17 at 23:13
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    Humans are live load, unless you're in the murder business and don't dispose of the bodies.... Most residential floors are default designed for 40-50 lbs per square foot, unless more is planned for. You have 60 PSF of dead load and 7 PSF of live load assuming the booth floor spreads the live load over the whole 36 square feet. If cowboying it rather than using an engineer, a few jack columns in the basement will help significantly. – Ecnerwal Aug 17 at 23:20
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    Weight per square foot is far less important here than the total weight of the thing. It isn't concern for punching through the sheathing that we're addressing, but the chance that every joist in the room fails spectacularly at once. For your comparison to be valid you'd need to consider 2400 lbs. of humans. – isherwood Aug 20 at 12:58

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