Posted: 3/9/2007 10:01:58 AM EDT
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Compatriots, what maximum weight of safe would you recommend for putting on a second floor of a house? Thanks! Kongo |
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My son had a Queen sized waterbed in his room on the 2nd floor and not near a load bearing wall. The floor joists are 2x10's on a 11' 3" span with no problem. If your joists are at least 2x8's on no more than a 12-14' span, I'd feel safe with a 500 lb. safe setting against a load bearing wall. 
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A king size waterbed holds 195 gallons, a Queen 162. Water weighs 8.34 lbs per gallon. 8.34 x 195 = 1,626.3 lbs 8.34 x 162 = 1,351.1 lbs And that only includes the weight of the water, no the bed itself. If you add a 250 lb man and a 150 lb woman, the King weight easily exceeds 2,100 pounds. A King is 76" x 80", or 6,080 sq inches. If you spread 2,100 lbs over and area of 6,080 sq-in, it makes a pressure of 0.35 psi. The point here is that weight is spread out. Almost all waterbeds I've seen have have solid bottoms that you cannot store things under. This spreads the load over a greater area so that it rests on multiple floor joists no matter what angle you place it in. Buy a sheet of 1/2" or 3/4" plywood, cut it in half, and screw the two halves together, making a 1" or 1.5" thick 4' x 4' sheet. A 4' x 4' sheet can support 800 lbs under the same pressure. 4' = 48" 48" x 48" = 2,304 sq-in 2,304 sq-in x 0.35 psi = 806.4 lb Do whatever you want to make it pretty. Route the edges, sand it, varnish it, polyurethane it. Place that sheet in a corner near a load bearing wall, and you should be good to go up to 800 pounds. If you cut the 8' x 4' sheet into 42" x 48" and 54" x 48" sheets, and place the smaller cut on top, you could expand the weight to 900 lbs without exceeding that same pressure. Remember!! That should be the weight of the LOADED safe, not unloaded. |
May I ask what you do for your day job? I am quite impressed with the analysis but wow! |
| I've got an 800 lb. (Empty) Browning in my 3rd floor closet. I figure it's no worse than four 200 lb. people in a group hug as far as the floor loading goes Think of it that way and you'll feel better. Find out what the building codes require for lbs. per sq. foot loading and then use the safe dimentions to figure out how many sq. feet it covers. |
I'm just a dumb fireman. But firemen have to know how much water weighs, and about the forces created by it when you put it under pressure. [hijack]If I'm fighting a large fire on the third floor of a building, using a 2.5" hose that flows 250 gallons per minute, then I'm adding almost 2,100 lbs of weight per minute. After just 5 minutes I've added 10,400 lbs of weight, and if the water has no place to drain, then it's just a disaster waiting to happen, especially if the floor starts to bow, then all the water flows the lowest point, making the problem worse.[/hijack] |