ok...retract my comment...I was going somewhere else with this on a residential note.

Thanks for the link AJ77, toxic's numbers make alot more sense now. I need to evaluate my joist spans and figure out a way to add columms underneath.

I have a 140 G. on the second floor positioned over the cantilever outset for a china cabinet in the dining room. It hasn't shifted in the three years or so that it's been there. Placing the tank against the wall with the joists running perpendicular to it like this:

t a n k

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is the strongest position it can be in and I have seen many large tanks on second floors that way without additional support.

Toxic, your 40lb/15lb per sq ft idea just clouds the issue. It doesn't relate to placing a load in one area of the room. What it relates to is the total weight the room (floor) can bear.
For ex. A 10' x 10' room can hold 15lb's/sq. ft. DW min. 10x10x15=1500. The room can hold 1500lb's DW.
The formula can't be used to work out how much a specific part of the room can hold.

LMAO.... someday Greg! someday, when you least expect it... :mrgreen:

I've got a 180 gal 72x24x24 above my garage as well, I put a telepost under the joist under my tank. It was around $70 at HD. I put it in right before adding water to my tank. No problems at all, great for peace of mind.

This is just the Building Code design criteria, shorter spans may hold more load. Remember dead load of 15lbs/ft2 is based on the weight of material only, not anything else.

I stand by my comment that 2500lbs over 12ft2 is serious overloading a floor based on the building code. Better be safe than sorry.

Again with out looking at the floor I can't say what it can hold exactly, and that is the reason for an engineer. It has been awhile since I have done the calculations.

Oh, and jsut beacuse your floor has not moved in 3 years that you can see does not mean there are no problems. I have seen enough over my 20+ years of experience in design & construction to say be careful.

I'm not worried :)

T, I wasn't questioning your experience, just noting that the numbers didn't equate to the specific problem. There isn't anything wrong with being careful and if it is easy and gives piece of mind to beef things up then it's all good but this type of question arises fairly regularily and for most tanks of that size there is no problem.
I can't recall the last time I've heard of a floor collapsing because of a non custom aquarium actually. I'm sure it has happened somewhere but if it was that close a call I'm sure there would be more incidents.

This week I have serviced a 230G., 300G., 150G., 140G. and a 135G. tanks; all on joisted floors - no collapses so far.

After having a closer look at my floor, I realize the joists run parallel to the proposed tank placement. This could be a problem right? Let me refresh the scenario again. Tank is situated along a load barring wall above the garage where there is a supporting joist and beam that lines up right in the middle of the tank position. The floor joists however runs parallel with the tank. The optional teleposts is no longer an option. I am now considering a 125g tank instead of the 180g first thought. Without additional support, can I just wing it with a 125g.

Since you're worried, get that engineering report, (might PM GreenSpottedPuffer if he'll give you an idea of cost, since he had it done) and figure how to stay big or you'll be kicking yourself later that you didn't.

Can you double up the first joist, expensive but install a steel beam?

Not sure how much room you have in your garage, but if it were me I would build a supporting wall in your garage directly below your tank. Make it floor to floor 12 inch centers with construction grade 2 x 6 and tie it in to the existing joist. If your anything like me you can always use more shelving in your garage ....:biggrin::biggrin: