Is this good enough for support??
 

So ill start my tank build later but I want your opinions on my support system please. I have a 6' 250g that runs with the joists. I made a support wall and stringers held on open side by 2 jack posts. The second is behind the furnace. All 2x8 with 2x4 for the wall. Its sitting on an out side wall. I had the spray foam guys spray the underside of the floor to help stiffen it up. Opinions please as I think its more than strong enough.

Good job. With a 2x8 beam doubled like that supported with 2 jack posts you are golden.
Should be able to park an elephant up there

Make sure your jack posts are screwed in and you are good to go. A structural engineer would cringe... but that'll hold the weight for sure.

Thanks guys. I know it's not pretty or spot on to an engineer but its the best I could come up with :biggrin: all I need it to do is help hold the tank up.

I was going to do the same as you when I had my 125g
A builder aquaintance suggested a 1/4" steel plate of 6x6" or larger under the jack post
The wood you have under it may split and could be a bit larger to prevent the concrete from cracking (it is a concrete floor, ya?)

I also talked to an engineer. Because of the cost of liability I didn't pay him for his services. He told me he entered my flooring and weight specs into his formula and told me that, if I were to pay him, he would suggest the above idea as a minimum, but because I wasn't paying him, he wouldn't be legally allowed to tell me that :wink:

The rest looks great. All I'd add to it is some cross bracing between the new support joists to prevent twisting

Doesn't make sense, a 1/4" 6*6 steel plate would be just as or less effective than the wood he has under.

What's under the jack posts? Concrete slab? If there are no footings poured under the jack posts the jack posts will probably crack the slab. When that happens the shift could cause failure. I've seen pictures of such failures.

Yeah point loading slab = bad. That's why structural engineers cringe but it'll probably be fine if that helps as it's really not that much weight. Personally would have build a wall in place of the beam and shimed it up tight under the joists to distribute the load.

That's a good idea. You could build yourself a little "load bearing" closet right there. :razz:

So I should just build another wall instead of the posts? From what I can find out the floor is at least 4" thick plus. I know I should have run joists and maybe tripled up but to much wiring and plumbing in the way for that.

How would it be less effective ? We're talking about point loading here
Steve and Myka pretty much covered what I was pointing out
Point loading the concrete floor will break it
By placing a larger foot of something that won't break under the load, you're spreading the weight out over a larger area, thus putting less stress on a smaller area of the concrete
And ya, the wood he has there under the post will collapse under load
Have you ever hammered any soft wood ? It compresses very easily
His wood will compress and/or split

That is typical slab thickness. The best thing you could do would be to jackhammer that slab out where you want the jack posts and pour a footing under it then hide the jack posts in a wall or something. I imagine you're not keen on that though. The length of a wall spreads the point load of the jack posts provided your bottom plate in the wall is at least doubled to help spread the weight instead of just bending. If you were really concerned, you could build a lintel (like over a window) made with a couple 2x10s to lay on the floor to spread the weight. That won't bend. :lol:

Just an example of spreading out a load



http://www.teachengineering.org/coll...03_figure7.jpgFigure 7. Bearing pressure on a shallow foundation.

This is, of course, the best solution
Then build a storage room around it

His 2x6 will be fine. I put 20,000kg buildings on standard 2x6 lumber without the wood having much compression.
Remember a hammer can easily hit with 600 psi.
1/4" steel is not very rigid, it's probably not spreading the weight much farther than an inch past the foot of the pole.


His tank and stuff is at max 3200 lbs. Even if 100% of that weight was on the two stands that is only 1600 lbs a leg. That's about 100psi per post on the concrete with just the 4x4 bottom of the post.

Even a poor concrete basement is at least 1500psi concrete. And then the fact that the concrete itself is spreading the weight to the earth under it. Unless you built on a swamp or think there might be erosion under the slab.

So even if the posts are in a bad spot with only 3" of concrete there still wouldn't be a problem.

And remember the squash blocks to the foundation wall are taking probably at least 35% of the weight, And even at a 16' span with the joists those could take another 35% of the weight without blinking.

Your image is only really true if that horizontal part is 100% rigid. The farther you get from the point load the less weight it is carrying. How much weight depends on how much the material you use flexes.


Building a little closet or a stub wall in the center will be more than enough.

Without ruining this thread, I'll point out that what you've said contradicts what you said previously and supports what I was trying to say

Maybe you misunderstood me when I was talking about where to place the 1/4" steel

Under the foot of the post, instead of the 2x6 he has.
I never said his 2x6 will transfer the weight to the large piece of wood he is using.
I simply said the wood and the 1/4" steel would displace the weight to a similar footprint. There will probably be some compression of the 2x6 if that wall is actually taking much weight at all, but once it does a slight turn of the jack will fix that right up.


A single stub wall in the center will carry the weight just fine. A closet in that spot would be great too.
But at the same time, nothing at all would probably never have an issue too. But a little over engineering is seldom a bad thing.

Maybe we're not getting the same impression from his photos

I see a small piece of plywood under his jack post. If it's larger, that would explain me talking about a larger plate of steel
If it's a length of 2x6, it's still not sufficient. Either way it will compress and would be better suited with something to spread the load out farther, away from the post, to alleviate any stress on the floor directly under the post

I agree with you saying he could just adjust the post as the wood compresses, but that's not a 'safe' method. As I said, the wood could also split, and then the whole thing is useless

I'm unclear with your statement;
"I simply said the wood and the 1/4" steel would displace the weight to a similar footprint"
I was talking about placing a large plate of steel under the jack post to spread out the load. I never mentioned any wood in my idea

What do you mean ?

:pop2:

I would post more pictures but can't. I have 2x8 under the feet as I thought it may spread the weight a bit more. The tank is sitting on two outside walls but running with the joists. The basement has a wall already there. Then I made another wall about 4-5" in from there and sat my stringers (hope that's the right term) on the wall then have the 2x8 doubled up sitting on the jack posts. I'm not that fussed about using this space so if its better to build a new wall and remove the posts I still can?? Thanks.

His photos are small. But it looks like a ~10" piece of 2x6 under the feet of the posts, well at least the one that I can see.

The wood will hardly compress. I seriously doubt it will split. His biggest issue with the wood is that it is not pressure treated and directly on the concrete.

The part you are unclear of is I am saying the wood he has will be as effective as the small thin piece of steel that you are recommending.


He is putting a tiny load on this part of his floor, he's not putting a 40 ton Leopard Tank in his living room.

How far is the span of your joists in this area?


flicker is an easy way to upload more photos.

Joist span is about 10' to the iron bar that's in the middle of the house.

2x10 joists? Looks like it's an older house, are they hardwood joists too? Or standard lumber.

So 10 feet from foundation to main load support?

You have nothing to worry about. Build extra support under the tank if you wish. But it's not going anywhere.

I might build a simple wall in the center of where the tank is, but it would simply be to take a bit of the bounce out of the floor for the fish tank. But I probably wouldn't do it until after I had the tank there and full to see if it's even an issue that needs to be addressed.

I am simply stating what I would do. I may not be an engineer. But I deal with all forms of construction trades every day, and for significant loads.

Just think about how much weight your living room is holding when you have a little party, and that's a live load which is significantly more force than the realistically static load of your fish tank. And the guest are normally in the middle of rooms, not hugging the load bearing walls.

Thanks. 2x10 old house from the 70's solid wood. Yes 10' from wall to main load support beam. So ill basically leave it as is then?? I'm happy with it I think and I shouldn't have any bounce with it like it is. Thanks :biggrin:

Ya it's not going anywhere. A 10' span is nothing, and your concrete has had a long time to get hard, it's not going anywhere either.

What you have is way overkill. The house itself would hold the weight just fine.

What material is the finished floor under the tank? As long as it's not tile, it's ok if the floor flexes a bit. It is also important to note that if the floor flexes too much and the stand also flexes too much the tank could break long before the floor would fail. Make sure the stand is well designed too. Personally, I would keep the jack posts simply because the tank is running parallel to the joists. if you do decide to remove the jack posts, at least add blocking between the joists under the tank and a couple joists beyond the edges of the tank to help with deflection.

Here's a great article written by a structural engineer (since 1976). Residential Wood Framed Floors and Aquarium Weights

His Conclusion: "Aquariums up to 55 gallons can be placed almost anywhere without much worry at all. Many tanks larger than 55 gallons and no more than 125 gallons will be okay, if they are placed in a good structural location and your floor framing is free from significant defects. For example, a 125 gallon tank, on a wooden stand, placed perpendicular to the joists up against a bearing wall, will often be okay without any additional structural support. If your tank is over 125 gallons, then it is likely that you should consider adding supports under your wood framed floor. Please realize that these are generalities that may or may not apply to your particular situation."

This is wood blocking that really shows no signs of compression after 3 years holding 45,000 gallons of diesel fuel.

http://farm8.staticflickr.com/7389/9...6e0b9df8_c.jpg
The weather has curled the edges up a bit, but it's fine.
They are sitting on top of swamp mats, which are sitting on muskeg. Even the mats have hardly any deflection in them.


Each of the 4 corners of all these tanks look like the above photo. They are all 100 barrel tanks.
http://farm4.staticflickr.com/3773/9...39f33dc0_c.jpg

I know this thread is beat to death. But just for future reference.