Structural Engineer Question - Floor Support

JaaxReef · Dec 22, 2021

So, when we built our house I designed one room to be the reef tank display on our main floor above the unfinished basement.
I told the builder we plan on keeping a large aquarium in that room and they put in extra support including what looks like sistered joists and double joist beams. There is also a load bearing beam just behind the tank as well. In the attached picture the tank sits about 3 feet in front of the support beam you see perpendicular to the joists.

With this additional support, realistically, what size tank can I put in that spot?

Thanks for your help!

dantimdad · Dec 22, 2021

Need to know dimensions of the beam, unsupported length and what is there to support the other side of the tank or is that just in the middle of where the tank will be.

There are online calculators also.

JaaxReef · Dec 22, 2021

dantimdad said:
Need to know dimensions of the beam, unsupported length and what is there to support the other side of the tank or is that just in the middle of where the tank will be.

There are online calculators also.

I’ll get some more measurements and get back to you.

I told the structural engineer from the builder it could be 2-3k lbs on the floor in the spot I planned to put the tank, but just looking for validation that it seems about right based on what they did.

JaaxReef · Dec 22, 2021

Main support beam is 14” tall, 5.5” thick and 10.5’ long. Looks to be a ply board of some kind. Tank would be 3-5ft in front of the main support beam and depending on size it would be 2-3ft from an external wall, with the tank running parallel to the main support beam.

In the other direction the joists run an additional 12ft past the tank to the other outside wall in front. Joists you see are 12”x2”. There would be 7-10 of them under the tank depending on tank length.

See highlighted spot for potential tank placement.

nereefpat · Dec 22, 2021

How big of a tank are you considering? I ask because sometimes people get concerned and the tank in question will be a 75 or something, and there is no reason to worry.

Zoa_Fanatic · Dec 22, 2021

JaaxReef said:
Main support beam is 14” tall, 5.5” thick and 10.5’ long. Looks to be a ply board of some kind. Tank would be 3-5ft in front of the main support beam and depending on size it would be 2-3ft from an external wall, with the tank running parallel to the main support beam.

In the other direction the joists run an additional 12ft past the tank to the other outside wall in front. Joists you see are 12”x2”. There would be 7-10 of them under the tank depending on tank length.

See highlighted spot for potential tank placement.

That looks like an LVL beam. Stronger than standard lumber but not as strong as steel. (Civil engineer here). At that size and depth it’s going to be able to take some serious loading but my concern is for your regular floor joists. The closer you can get the tank to an exterior wall (assuming that the wall sites on the concrete foundation of your basement, the better off you’re going to be. If you’re running 3-5 ft out from that support and you want an egregiously heavy tank I recommend adding another support around 1ft from where you expect the tank edge to be if possible. This only matters if you’re doing like a 5’x10’ shark tank or something. If it’s like a 75G like @nereefpat mentioned, my 60 year old house can support them no issues.

LeftyReefer · Dec 22, 2021

You will be fine. They added more than enough support unless you are talking a huge huge tank.

JaaxReef · Dec 22, 2021

Zoa_Fanatic said:
That looks like an LVL beam. Stronger than standard lumber but not as strong as steel. (Civil engineer here). At that size and depth it’s going to be able to take some serious loading but my concern is for your regular floor joists. The closer you can get the tank to an exterior wall (assuming that the wall sites on the concrete foundation of your basement, the better off you’re going to be. If you’re running 3-5 ft out from that support and you want an egregiously heavy tank I recommend adding another support around 1ft from where you expect the tank edge to be if possible. This only matters if you’re doing like a 5’x10’ shark tank or something. If it’s like a 75G like @nereefpat mentioned, my 60 year old house can support them no issues.

I’m thinking like 180-220 max. So hopefully it looks good enough for that!

Randy Holmes-Farley · Dec 22, 2021

As a related question, anyone know a good way to locate a consulting structural engineer that would look at a very old residence and give advice on whether it as adequately supported on the underside? I recently bought a home that was built in 1800 by a bricklayer for himself. Whole logs for supports, etc. Since some have old powder post beetle damage and other issues, I just want to be sure it is adequately supported for normal home use (nota giant reef tank), but cannot seem to locate suitable folks (western massachusetts area) using simple google searching.

Zoa_Fanatic · Dec 22, 2021

JaaxReef said:
I’m thinking like 180-220 max. So hopefully it looks good enough for that!

I mean you could probably fit a bigger tank than that over that beam no problem you’d just need to minimize the tanks footprint so it doesn’t go way past where your beam is. A load like that is gonna do better positioned as close as possible to an exterior wall and as close as possible to directly over that beam. I’m not a structural to give you a definitive yes or no I just had some light structural training since it’s part of the CE curriculum and is a CE sub-specialty. I imagine it could handle it but you’re pushing 2200 lbs with a 180G without the rock. I’d be careful not to go too high. You want most of the weight to be closer to the exterior walls ans they beam because all the joists do is transfer the load down onto the LVL beam or out to the walls.

Zoa_Fanatic · Dec 22, 2021

Randy Holmes-Farley said:
As a related question, anyone know a good way to locate a consulting structural engineer that would look at an very old residence and give advice on whether it as adequately supported on the underside? I recently bought a home that was built in 1800 by a bricklayer for himself. Whole logs for supports, etc. Since some have old powder post beetle damage and other issues, I just want to be sure it is adequately supported for normal home use (nota giant reef tank), but cannot seem to locate suitable folks (western massachusetts area) using simple google searching.

I work with a nationwide firm that likely has an office in your state called Stantec. They should be able to take care of you.