Floor bracing

Nor'easter Reefer · 2026-07-23T10:30:06-0400

So who's got any knowledge kn bracing floors? I'm fairly certain I have a solid idea of what i need to do, yet everytime i discuss with someone i find out either my plans overkill and a waste of money, or they tell me to go even further overkill haha. Included is a couple pictures. The picture of the flow joists from below..

i have a wall immediately above it. Thats the wall my tank will sit in front of. I intend to be around 6" off the wall. I know my beams thicker than my wall, and I have determined which side of the beam it foavors, or if its center. I also have noticed in one spot the missed a joist hanger. And looks like it needs a bit of extra support as its not butted right up to the beam entirely. Next up I have this drawing that shows where my tank will sit in relation to the lally columns/steel posts you can see in the picture.

So I have a steel H beam from a solar job I was subbed out to. The kind they drive into the ground to build the array on. I was thinking I could repurpurpose this, and put a column on each end. I figure i'd line it up so the column sits in line with the face of the aquarium. I figure the beams close enough where I dont have to worry about any flexing. And if I brace up that one floor joist, I shouldn't have to worry about any shearing. My questions I still have:

Should I sister up any 2x10?

My tank has something like 12 adjustable feet. Idk if they line up to land on a floor joist for each one, should I out something down? Or really dial in my layout and use 2x10 blocking under where my feet will go? I'd hate to support the floor joists just to have my subfloor flex so much it fails/flexs too much

BryanM · 2026-07-23T12:10:04-0400

I am not a structural engineer.... But if this was my house I'd be placing something between the floor and the 2x10's that were under the tank. The wall probably doesn't need anymore help, but I would feel a lot better if where the tank sits it had more support.

I basically have the same setup, 6 foot tank sitting in front of a wall. I went under the house and used concrete footers and 4x4's to do basically what I said above. You can jump in front my my tank and not notice it or water move because of it.

Of course I hurt for a week after that.. crawling on my belly on the ground under the house with no room to move... at 56 I'm at least half way to old man status, I'm a little past my prime for that sort of work.

exnisstech · 2026-07-23T12:18:49-0400

I didn't ask so I probably did it wrong

I placed my 330 in a location pretty much identical to where yours will be. I built a beam out of 2X10 and used a couple of pole jacks as supports. Mine is placed about where the red line is.

Nor'easter Reefer · 2026-07-23T12:32:41-0400

BryanM said:
I am not a structural engineer.... But if this was my house I'd be placing something between the floor and the 2x10's that were under the tank. The wall probably doesn't need anymore help, but I would feel a lot better if where the tank sits it had more support.

I basically have the same setup, 6 foot tank sitting in front of a wall. I went under the house and used concrete footers and 4x4's to do basically what I said above. You can jump in front my my tank and not notice it or water move because of it.

Of course I hurt for a week after that.. crawling on my belly on the ground under the house with no room to move... at 56 I'm at least half way to old man status, I'm a little past my prime for that sort of work.

I HATE floor shake, so im more prone to overbuild anyway. So are you saying you took some 4x4, cut to fit between the floor joists, and nailed them into place ? Essentially the same way you block floor joists just shoved up tight to the floor? I was thinking of doing this as well. I have really easy access, so i was thinking of doing 2x10 sistered together.

Nor'easter Reefer · 2026-07-23T12:35:04-0400

exnisstech said:
I didn't ask so I probably did it wrong I placed my 330 in a location pretty much identical to where yours will be. I built a beam out of 2X10 and used a couple of pole jacks as supports. Mine is placed about where the red line is.

I'm sure i'm overthinking it, but my last tank had so many things I under thought about and i'm really hoping to do a better job this time haha.

I had one guy tell me I should put two posts and my beam, but he said put it right under the tank itself. I felt i should at least hug the face furthest from the wall vs middle of the tank.

ajhudson15 · 2026-07-23T12:38:59-0400

we had a 220 gallon a few years back and went into the crawlspace and added a railroad tie to support the extra weight. Would never know there used to be a fish tank there.

exnisstech · 2026-07-23T12:50:21-0400

Nor'easter Reefer said:
I'm sure i'm overthinking it, but my last tank had so many things I under thought about and i'm really hoping to do a better job this time haha.

I had one guy tell me I should put two posts and my beam, but he said put it right under the tank itself. I felt i should at least hug the face furthest from the wall vs middle of the tank.

I did mine like the picture which sounds like your thinking. If the center beam wasn't there I could see putting it under the tank itself. But I've built houses not designed them so there's that. I didn't ask when i did mine because I figured I'd get too many over thinkers. I see some stands people build and just laugh because they could support a truck and are so heavy it's like moving another tank.

PS I ran two 180g tank in our 11x14 living room on two walls for over 6 years with no additional floor support added. I guess I'm just wreckless but I think that comes with having no education so I'm probably ignorant as well but I get stuff done

Nor'easter Reefer · 2026-07-23T12:58:40-0400

exnisstech said:
I did mine like the picture which sounds like your thinking. If the center beam wasn't there I could see putting it under the tank itself. But I've built houses not designed them so there's that. I didn't ask when i did mine because I figured I'd get too many over thinkers. I see some stands people build and just laugh because they could support a truck and are so heavy it's like moving another tank.

PS I ran two 180g tank in our 11x14 living room on two walls for over 6 years with no additional floor support added. I guess I'm just wreckless but I think that comes with having no education so I'm probably ignorant as well but I get stuff done

I think an honest effort is probably more than a lot of people put into it, and is probably more than enough! I agree, I can probably just go with my plan and call it good! People put a lot less thought into where they stick a tank all the time

plus, if your ignorant, your also not stressed about it either

BryanM · 2026-07-23T13:05:14-0400

Nor'easter Reefer said:
I HATE floor shake, so im more prone to overbuild anyway. So are you saying you took some 4x4, cut to fit between the floor joists, and nailed them into place ? Essentially the same way you block floor joists just shoved up tight to the floor? I was thinking of doing this as well. I have really easy access, so i was thinking of doing 2x10 sistered together.

Yep, this is exactly what I did. Super solid. There are 5 of them under the floor, supporting the tank and a bit beyond where it sits.