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Supporting sub-floor in crawl for heavy aquarium?


Frank512's Avatar
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04-17-14, 06:44 AM   #1  
Supporting sub-floor in crawl for heavy aquarium?

Hello,

I am planning to put a 180 gallon aquarium (could weigh about a ton on a 2'x6' footprint) in my living room soon, but I had a look inside the crawlspace and much to my disappointment, the floor joists are only 2x6's. If the weight slowly sag's the floor, and the tank becomes out of level, the water could put pressure on the tank seams, eventually causing them to fail. The last thing I need is 180 gallons of water on the floor.

The crawlspace is quite cramped. There is only about 12" give or take from the bottom of the joists to the ground. I was hoping to take advantage of this and just build up some support from the ground to the bottom of the joists. I am trying to do this myself as simply as possible because the aquarium set up is going to cost quite a bit as it is. That said, I'm really not looking to pull out the insulation and start sister joists, or dig to pour concrete footers. It's going to be a bit hard to work under there as it is.

What would be my easiest option? I wish I could just find some short threaded posts and use about 8 of them concentrated directly under where the tank would be, but the shortest I have found is 12"-16" and they are like $30 a piece. I am just not sure the best way I could "build up" support from the floor and make it the exact height needed to reach the joist and support it. Thanks for any advice.

Frank

 
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ray2047's Avatar
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04-17-14, 07:38 AM   #2  
I'd use two 4x6 at 90 to the joists that will be under the aquarium and solid concrete blocks under the 4x6 beams. Removing a section of floor may be the only way to access if the crawl space isn't dirt. Even if it was dirt I might go that way instead of tunneling.


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04-17-14, 07:39 AM   #3  
Well, the water in the tank is about 1500 lbs if you fill it completely.

Although this would not be code approved in any way, shape, or form...you could use lengths of 4x4 set atop heavy concrete 1' x 1' pavers. Cut the bottom flat and the top with a very slight angle with the longest length being just the distance from the top of the paver to the bottom of the joist....put them in position then pound the top into place supporting the joist. You'll need to compact the soil under the paver if its loose. You could also use something like 2x6 running up the side of the joist from the paver, then screw it in place on the joist. That would allow for adjustment if needed.

Either way, you'd probably need 8 or more of these supports and should install blocking between all joists in the area and one joist past.

I don't know how the heck yer gonna be able to do this in a 12" tall crawl unless you have a very handy 6 y/o child.


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Frank512's Avatar
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04-17-14, 11:29 AM   #4  
Well, I certainly didn't expect anything I would be able to accomplish on my own to be code approved As far as working under there, I don't really know how I am going to manage. The good thing is I am a small guy so I can actually fit in there, but it's pretty uncomfortable, that's for sure.

The crawl space is dirt and my luck right where I need to put the tank, there is wiring all over the place besides. The rest of the crawl? Nothing. This is turning into a much larger project than I would have liked, but I have been wanting to do it for years.

Well thanks for the idea's.. I thought that I would just stick some 1x1 concrete blocks on the dirt, then build up to the joists. I couldn't figure how I would get the exact height I needed. I was trying to not disturb the dirt. Cutting the wood on an angle might just do it. Here is a pic (ignore the junk on the ground), it looks way more spacious then it is :NO NO NO: The tank would be going along the right wall there.

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04-17-14, 12:33 PM   #5  
Something to this effect would make my life a whole lot easier. Deck Post/Base Adjustable Supports, 8-5/8 to 11 inch, Khaki (12)

 
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04-17-14, 12:35 PM   #6  
You won't gain much without pouring a footing for the block in question. The dirt will compress and you won't have the support you planned on. I've worked in worse, so you should dig a 24x24" square, at least 8" deep and pour concrete in it. Once it has cured, you can stack your block on it to the beam, and shim it the rest of the way to ensure a secure fitment.

 
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04-17-14, 05:40 PM   #7  
Yeah I have thought about that. I was kind of hoping I could get away without going through all that. I will look into it. I may as well do it right, or not do it at all.

 
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04-18-14, 09:38 PM   #8  
I'd be inclined to go with something along the lines of what ray2047 suggested--a few 4 x 6 spreader beams, several feet apart and spanning at least 3 or even 4 floor joists, and supported by stacked solid concrete blocks. You can sometimes find 4 x 8 x 16s for a few bucks each, and you'd only need about 12 of them (one stack under each end of each beam). You could get away without a permanent footing (why build permanent for a temporary situation?) by beating the loose soil with a 3-lb. maul on a scrap timber block before setting the first concrete block, spraying some water between beatings to reach optimum moisture content. Taper-cut some 2x shims and wedge them into place with the maul between the top block and the underside of each end of each beam. The existing wiring shouldn't be a problem, as you can simply drive the wedges between the joists and the wiring. Things will go much easier if you first attach the beams to the joists using a few inexpensive steel L-brackets--working on your back in a confined space will be hard enough, without having to fight too many things all at once, while not having enough hands. If things loosen up over time and gaps develop, just wedge a few more (thicker) shims into place when needed.

And the real beauty is that you can take everything with you when you move to your next place. Provided the fish go along with you, of course.

 
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04-19-14, 04:14 AM   #9  
I respectfully disagree with not using a footer. Life is temporary. Why build our life around that. I would expect building something safer to handle the weight would take precedence over permanence.

 
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