Jacks under floor...

brian, you have no idea what I have a background or education in, please keep the insults to yourself. You are talking to me as an "expert", yet seem to want to get "experts" opinons?

For the record, I am fully aware of the difference between a dead load and live load. I am fully capable of reading joist tables, span tables and other engineering data. If you wish to talk about laods in general then we can discuss all of the fine details and use engineering and structural analysis to design the floor or supports to hold the load with the desired amount of deflection or safety factor. If you really understood joist and span tables, you would also know that in the real world they are only a starting point, and can be somewhat useless or misleading in many situations. You may also want to note that many of the "building codes" that you will look at have nothing to do with real world safety, instead they are passed by people who "think" they are doing something useful, by poloticians to generate "Permiting" revenue, or politicians to force "certification" and prevent competition for established contracting firms (pork at it's worst). I can show you pages of such codes here in pittsburgh, and any other city, township, or municipality.... take good look at the new BOCA codes one time and tell me how many of them are relavant?

This brings us to the question at hand, and the "general answer" that seems to keep getting lost in all of the back and forth.

The fact is that most modest sized tanks will be just fine in most situations. If your 90 gallon tank breaks the drywall in your basement, causes floor joists to crack or dishes to slide off the table, then you have other problems and have likely already severely overlaoded your floor structure, or you live in a shack with 2x4 joists 24" on center. I am sorry but this simply isn't worth the trouble your making it out to be. A 300 gallon tank? Well that may be something to really look into, but then again, I don't see it falling through a floor either, as it's footprint is rather large.
 
I set pillars every day for buildings,so I normally set 2 pillars of 8 inch blocks and wedged off my floor snug. The tank was setting level and after 3 years it has sank an 1/8 of an inch. Wood will slowly crush, granted it may only be a 64th, but no 2 x 10 will ever push back up 2000 lbs. I don't how bad of a grain it might have. Southern yellow pine it the most notorious for this. Alot of placing pillars will also depend on on your floor system. Do you have 2 x10's as floor joists? What are the joists on center? Is the tank near a wall where there pillars in the back? Or is there a wall. As long as you brace the floor, you should have no problem, just don't jack the floor up, you want the floor to remain in the place it is. This will cause no undue stress to any of the floor around it, but should keep your tank level for years to come.
 
superzman,

to answer your question if you where to place a support between two supports that new support could become a new main support. and if that new main support was not sturdy it could collapse thereby rendering itself useless. you could easily be ok without any additional support. otherwise we would have had a rash of collapsing homes in the 70's what with all the king size waterbeds with mirrored canopies and such.
but adding in an extra support would not likely do harm unless you jacked up the house with it.
 
I haven't seen anyone give the obvious advice: if you have any doubt, consult a structural engineer. Provide him with some measurements and he'll be able to tell you what needs to be done.

I'm in the process of setting up a 240 gallon tank in my living room. The structural engineer recommended reinforcing my floor with some extra 2x10s. This cost me $250 in consulting fees. I have no background in structural engineering and every situation is going to be different anyway. This price is worth it for the peace of mind alone.

For what it's worth, here is a diagram I sent to him to give you an idea of what they'll want to know. Unfortunately my tank will run parallel with the joists instead of perpendicular, which is not optimal.

His advice in my case is to add 2x10's so that they are 6" o/c south of my load-bearing beam (top half of diagram, i.e. there needs to be 5 joists under the tank), and 8" o/c (3 joists under the tank) for the north side (bottom half of diagram).

Hope this is at least interesting to someone. FYI, I estimated the weight of the tank, stand, canopy, rocks, and water to be 3000 lbs worst-case. That's probably on the high end.

showphoto.php
 
Just go buy you 2 LVL beams, call Georgia Pacific and consult one of their free engineers by phone and put one on each side of your tank. The floor will not move then....unless a hole opens under your house and swallows it!!! This way you will not jack up the house, no supports, because some people seem scared of them ( I have no idea why?) This will cost a little more but you will never have to worry. You will just need some help installing them. Go and buy you some Simpson brackets that are made to hold the LVL beams up and problem solved.
 
Slickdonkey,
What does o/c mean? off center?
Thats a useful diagram, thanks.

KH971,
are those LVL beams to be put adjacent to the joists already in place?
By the description, it sounds like they are placed vertically, like the posts. Is that correct?

Thanks,
Z.
 
Ahhh.. now I get it. Somehow i my mind I had them going horizontal (east - west) not vertical (north-south). Thanks slick donkey.
 
Just for the record: I am no structural engineer, so take my suggestion with that in mind.

Fortunately for me, my neighbor is one of the main structural engineer for the state of California. I believe he now writes building code for the state. My house has a raised foundation with 19" of clearance underneath. When I wanted to put a 120 gallon tank into my living room, I asked my neighbor what he thought. He did some calculation and told me that based on the weight he estimated, he would never sign off on the project. He helped me come up with several possible design. He said the correct way to support the floor would be to dig a 3 ft hole and pour a concrete support, and then reinforce the floor. Of course, we both knew that with 19" of clearance, there was no way this would happen. He came up with another design similiar to what Patteo posted with one major difference. In Patteto's design, he used a cement pad and leveling sand. I suggested using a cement pad, but my neighbor was afraid that the weight could crack the cement pad, thus resulting in failure. He had a better idea. Instead of the 2x4 header, I used a 4x6 header. Instead of the cement pad, I laid a 4x6 pressure treated wood on the ground. Then I put the adjustable steel colum beter the the header (which was pressed against the floor joists) and the 4x6 pressure treated wood (which laid directly on the ground). Since my tank is only 48" long, I purcased an 8 ft section of pressure treated 4x6 and then cut it in half to two 4' sections. I painted the end of the section to help prevent/reduce rot.

My neighbor inspected my work, and he said that he was very comfortable with what we had done.

Anyway - just another way of reinforcing a raised floor.


Floor-reinforcement.gif
[/IMG]
 
ok ill play devils advocate.
all this to support a 120 gallon tank when the stand to support the tank is 6 to 8 4"x1/2" pieces of pine
 
<a href=showthread.php?s=&postid=7024773#post7024773 target=_blank>Originally posted</a> by douggiestyle
ok ill play devils advocate.
all this to support a 120 gallon tank when the stand to support the tank is 6 to 8 4"x1/2" pieces of pine
Click to expand...

But the structure of your floor is totally different than the structure of your stand. The stand is designed specifically to support the weight of the tank. The floor is designed as a "general case" with the load being distributed across the room by the joists.
 
The same guy would likely not "sign off" on a waterbed or a gun safe either.

I am amazed at the panic that this SMALL load is causing with people. You guys can spend several hundred to several thousand on structural studies, building permits, support hardware and inspections. I on the other hand would not hesitate to put a 120 on any floor of my house. I know more than a few people who have them and know of none with structural problems. Is this scientific or engineered? Nope, but then agains it's just 1200 pounds, not 12 tons.
 
We did break the joists at a house one time, but then again that was 3 kegs, and at least 80 people jumping up and down in one living room. Actually seen that happen twice in my short life.
 
<a href=showthread.php?s=&postid=7026869#post7026869 target=_blank>Originally posted</a> by BeanAnimal
The same guy would likely not "sign off" on a waterbed or a gun safe either.

I am amazed at the panic that this SMALL load is causing with people. You guys can spend several hundred to several thousand on structural studies, building permits, support hardware and inspections. I on the other hand would not hesitate to put a 120 on any floor of my house. I know more than a few people who have them and know of none with structural problems. Is this scientific or engineered? Nope, but then agains it's just 1200 pounds, not 12 tons.
Click to expand...

Yeah, maybe so... all I'm saying is I consulted an engineer and he recommended reinforcing my floor. He's not doing the work, so there's nothing in it for him, he gets paid either way.

It all comes down to this: it's your floor, do what you want.
 
Slick.. that pretty much sums it up. You by no means did the wrong, and the engineer certainly did you give you "bad" information. In the end you felt comfortable consulting him and using his advice, thats all the really matters.

Bean
 
Here's a link to a website that explains a lot of the questions posed here. He does a very good job of going through all the junk and giving the facts.

Good luck with your tank,
-- itZme
 
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