300 Gal Tank and Floor underneath it.

maro1

maro1

New member
I am putting in a 300 Gallon tank. 6'x4'x2'tall. My question is will I have to support the floor underneath it? It will be near the wall on the end with 3 Joists running length wise under it. The joists are 2x10's with 3/4" plywood on top of them. The only way to access the space under the floor is to pull up the floor.

Mar:rollface:
 
There was a large thread on this and a guy was debating on supporting the floor and he was setting up a 120 gallon. I think you should support the floor, that will be at least 3000 lbs.
 
You cant put that much weight on 3 floor joist. I doubled up all my floor joist(8) in my new house and the back end is on a load barring wall and I am putting two jacks under the front corners of the tank. But you will need footings under the jacks because that much weight will crack a floor thats only 4 inches thick.
 
Friday I am going to pull up the floor. My plan is to add 3 more joists. My question is this.

I have read that I do no need to runn them all the way to the ends and that I can just sister them (attach new 2x10's right to the existing joists effectively doubling up the existing joists. What do you think of that plan or what do you recommend?

The whole span is 14' and I will run new 14 footers right alongside.

Mar
 
I have a similar situation myself. But I was going to add two small footings and floor jacks under the joist running the center of the tank.

Mar, I would suggest supporting the floor in the vertical position as well as beefing up the joists like you are.

But I'm not sure the jacks are the best or only way to go. Does anyone else agree or disagree with me? I'm no expert by any means.
 
If I added jacks as well do I need to poor cement pads? how thick? depth?

Or could I just set a cement block?

Mar
 
<a href=showthread.php?s=&postid=7161160#post7161160 target=_blank>Originally posted</a> by maro1
If I added jacks as well do I need to poor cement pads? how thick? depth?

Or could I just set a cement block?

Mar
Click to expand...

Extremely good questions. I would make sure you either get a professional opinion on that or get at least 10 or so opinions from this board. I wouldn't go with just one or two people saying its okay or not. That make sense???

The problem is if you dont support the tank enough, it probably wont fall through the floor, but it may cause other structural problems like cracks in your walls and ceiling or a sinking floor, etc.
 
Yes you can laminate (or sister) the joists togther, just make sure you use lots of nails! and they must be full length ( sitting both ends on load bearing surfaces). Posts (not jacks) could be used to great advange under the tank to the ground. Yes concrete should be used as a footing. usually 18" square is good But one lare one for all posts may be easiest. The depth will have more varaibles, but the deeper the better. Frost level (if any) should be know to factor in for the depth of the footing.
Also you didn't give any info on the load bearing walls.
If your house is a above ground only sitting on blocks than there is no load bearing in the outer wall and the full weight of the tank must be supported with new or extra supports.
If you have outer cement walls with footings than that can help with weight transfer.
In the end getting someone with the knowledge (engeneer) in to look and see any unknown info is the best way to go.
Good luck
 
The 14' joists both sit on a concrete wall. It is my understanding that it is difficult to get the new 2x10's all the way to the ends. Because of some compression from the existing walls. Can you notch the ends to get them there?

Or as I have read elsewhere. getting them all the way to the ends if you are sistering them is not necessary as your are only adding shear strength to the ends.


There is a smal gravel filled crawl space of 18" under the floor and the year round temp is around 50 degrees.

Mar:rollface:
 
You are right about the shear strength comment. But you do need the strength unless you are putting in the posts.
You can notch and shim if nessary.
If I were you I would go the support the weight of the tank with 4 posts route.
What is the ground like (clay, sand, swamp) under the house?
If it is well packed than patio stones under the posts will work and run the posts to laminated 2x8 or 2x10 running 90 deg to the floor joists.
The big problem with this is that if the ground ever sunk than so would the jack and stop supporting the tank.
And as you said the only way to access the crawl space is through the floor making it very hard to moniter or repair.
 
I will notch the 2x10'2 as I place them.

The ground underneath is pretty firm with a few inches of hard packed gravel on top of it. The ground here in Iowa is fairly solid.

So you would add 4 posts as well?
I can get 4" thick round patio stones.

Mar:rollface:
 
104937z217-med.JPG


Here is a photo of the 300 Gal I am putting in my livingroom. I will take some shots as I go through the process of strngthening the floor.

Mar:rollface:
 
Here is the placemant of my 300 gal tank. The sheet of plywood shows the footprint of the tank and stand. The joist run from left to right in the pics and the wall to the left is an exterior wall. The wall at the back is not a load bearing wall that I can see. Then the last pics are some guys waiting to move into their new home.
104937z218-med.JPG


104937z219-med.JPG


http://reefcentral.com/gallery/data/500/104937z220.JPG

Mar:rollface:
 
If the wall at the right side of the picture is a exterior concrete support wall (should be min 8" thick) and on a footing (important) and the floor joists run 90 deg to that exterior wall and are on 16" centers. Than I would run a laminated header 90 deg (parallel to exterior wall) to the floor joists made of 2 2x8 with lots of nails. Then support that with 3 or 4 posts sitting on a full length footing dug about 18" into the ground. Put the header about 6" to 10" back from the front of the tank. (This will give you a cantalever) You could place the posts on patio stones but the stones could break from the weight or improper placment and it would be difficult to repair.
A proper footing is not that expensive or hard to do (more work than patio stones). But I say do it right the first time.
If the exterior wall is not what I am thinking than repeat the header, posts, footing just inside the exterior wall. This would give you a total of 6 posts.
As far as needing more floor joists. It is a good idea. But with the info above will give you a span of about 3.5' to 4' which is good and low for 2x10 (assuming 16" centers) But like i said it is a good idea to double them all up.
Hope this helps
And nice tank.
 
Floor supports

Floor supports

http://reefcentral.com/gallery/data/500/104937z224-med.JPG

I have the floor open now. Monday we are going to finish underneath. The ground is hard and here is what I am planning. Let me know what you think. The red outline is where the tank will sit. I am going to sister the 3 joists that the tank will be over, the blue lines show the joists I will sister. Running the other way the green lines show where I will place a beam under the joists and the yellow shows where the cement pads will be that I am going to put posts on that attach to the beams for additioknal support. There is only 5" clearance below the bottom of the joiosts to the ground. What do you think?

Mar
 
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