Floor Deflection from Aquarium

Old 11-27-17, 05:35 PM
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Cool Floor Deflection from Aquarium

Hello board, first time poster here.

I'm looking to add a 180 gallon aquarium to my first floor (approx 1800 pounds) in a large room on a relatively new construction house. The aquarium will be oriented parallel to the joists (not ideal). Fortunately I have the original engineering specs for the house, so I nicely asked the original engineering company if they wouldn't mind re-calculating the joists' engineer loads with an aquarium on top. Results show that the joists' total load deflection increases from 0.45" to 0.73" on the 25' joist, and live load deflection increases from L/883 to L/489. So basically, the aquarium will cause the floor to sag an extra 0.28" in the middle of a large room. The added load is still well within code, but it's right against the L/480 max deflection the house was built to. The floor below it is a finished basement. The engineer noted the additional weight "may cause ceiling cracking" in the basement. And since I'm not paying the engineer, I'm not expecting him to render any opinions as to whether this extra deflection is a problem or not other than telling me if it's in code (that's where you all come in).

So my question is, on my nice, newish house, is the extra 0.28" deflection worth bothering with? I don't want preventable squeaks and cracks from an aquarium, but on the other hand, my basement has some small cracks anyway from foundation settling, and I don't want to throw money down the drain for joist reinforcement to prevent a "problem" that is unlikely to be noticed. Do any of you with experience in this have an opinion on what level of extra deflection is worth taking care of in a nice, new home, versus what can be ignored? I'm happy to pay for the joist bracing and sistering if needed, but if not, I'd rather spend that money on more fish for the aquarium.

Thanks in advance!
Old 11-27-17, 06:18 PM
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Welcome to the forums.

I'm not the pro in this forum and you were asking for opinions.
I would not consider putting that type of weight in the middle of the room without reinforcement in the basement. If I was set on putting it in I'd want to sister at least two of the floor joists in that 25' stretch. I'd open the sheetrock up between three joists and make the additions. This way you could use full sheets of rock for the ceiling repair.
Old 11-28-17, 01:38 AM
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Or, depending on the location in the basement you could simply install a $30 adjustable post across 2 or 3 floor joists which would be more than sufficient to pick up any deflection from the additional weight.
Old 11-28-17, 08:09 AM
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I would recommend opening up the ceiling in the basement and adding sistered joists and blocking.

I would reinforce the floor before the aquarium goes into place. Even just blocking would help distribute the load some. I would also choose a stand with a continuous base, not 4 legs.

You have to figure there might be a lot of people standing around the aquarium.
Old 07-27-18, 09:13 AM
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1800 lbs would be a correct guestimate for the aquarium but what about those four 225lbs friends that come over and admire your beautiful aquarium and any addition furniture that might also be sharing those floor joist. It could add up and cause more problems. A post and beam directly below the aquarium would be the easiest solution. As long as you don't mind the post in the basement area.


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