Ok..what is a realistic weight for upstairs?

[BA]

did you get a hold of the builder>???whats the verdict?

[PeeJ]

I passed...that's why all my live rock is in a trash can and the tank missing....its getting "holed."

[::pete::]

I came across this in a different thread and thought it might shed some light.

My minor is in architectural engineering so I can shed a little light on the subject. I will try to keep this simplistic.

The standard code for weight bearing in a residential home on the second floor is 50 pounds per square foot (40 pounds "live load" [People/furniture/etc]) and 10 pounds "dead load" (the weight of materials (wood, tile/carpeting/etc.) - this is a standard measure across the U.S.

The part of the equation that you are not taking into consideration is Deflection. Most codes state that building must have no more than a 1/360 Deflection per square foot. That means that the floor can sag no more than 1/3 inch at maximum weight load. Most floors will sag much less than that until 3 times maximum weight is applied. At about 150 pounds per square foot, most floors will begin to sag that 1/3 inch due to the flexibility of the flooring joists and sheathing.

Keep in mind that newer construction has more give and flexibility than older construction because the wood is greener. Most second floor construction is 2x10" joints on 16" centers which surpasses code by about 75% that is why a 200 pound man can jump up and down and the floor shouldn't waver much but it will give some - within expected guidelines (1/3" to 5/8" Deflection).

The real question is how much weight can it take before you should be concerned? Aquarium weight is constant - Heavy, but constant. The fish and rock don't jump around too much causing rocking. This has advantages in that gravity is a constant and pulls at the same rate 1g.

Let’s say for arguments sake that 75 gallon tank is full with sand, rocks, water, fish and you have a 20 gallon sump with a 10 gallon refugium.

You have put in approximately:
Sand - 60 pounds
Rock - 120 pounds
Water - 720 pounds
[80 gallons (75+30-displacement of rocks and sand) at 9 pounds per gallon.]
Stand - 40 pounds
Tank - 100 pounds
Canopy/lights - 60 pounds

Grand Total: ~ 1,100 pounds.

Lets say your tank is a standard 75 gallon 48"x18"x20" which would place a live weight of 183.3 pounds per square foot. (1,100/6 square feet.) This should cause a maximum displacement of no more than 5/8" deflection or sag. Your floor should be able to handle the live load without an issue unless your builder took some extreme shortcuts.

Now I will say that if you are attempting to place the tank over an expanse (i.e. a bridge or loft area), you might risk a higher defection because of fewer support beams - so be aware. Also, near the wall - which is where we usually place a tank - is stronger than in the middle of the floor.

IMHO, your construction will handle your tank without catastrophic failure as long as you don't get 30 people jumping up and down on your second floor with the tank full...