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Reinforcing floor for large tank?

I would buy that corded impact driver for the simple reason that the battery pack for mine is incredibly expensive, and even though being cordless is convenient, the weight makes it so that I would gladly buy a corded one!

So two 2x4s would work as well as the 2x8? Then is the purpose of sistering simply to reinforce the original joist, or does the sister itself act like a whole new joist? I mean, instead of sistering, I could just add the joists in there I suppose... ??

I'm inclined to use the notched/refilled 2x8 rather than two 2x4's I think it just "seems" like it would be stronger. I gotta post some pics ...

V
 
I need to clarify something first.
I really enjoy helping and throwing out a lot of ideas.
But these are just ideas. Not guaranteed to be correct by any means.
And sometimes I do not designate opinion from fact as well as I should.
I do understand mechanical engineering formulas and concepts well, but I have
no real house-building experience, and I am an electrical engineer by career.
If you are unsure, it might be worth hiring a real pro.

What is key - make sure you do enough to sleep worry free at night.

--

Vincerama2 said:
So two 2x4s would work as well as the 2x8?
Click to expand...
No. For one thing, two 2x4's is only 7" of wood, where a 2x8 is 7.5".
Plus a larger single piece can handle imperfections (knots) much better.
The data is probably online somewhere. A guess would be 15% difference.

Vincerama2 said:
Then is the purpose of sistering simply to reinforce the original joist, or does the sister itself act like a whole new joist? I mean, instead of sistering, I could just add the joists in there I suppose... ??
Click to expand...
The problem - your new joist is not connected to the floor. That is a big difference.
Having that connection keeps the joist from moving/tipping, and adds a compression member component.
If you tie the joists tightly together, you basically get the full benefit.
It is then essentially - a double strength joist.

Some math notes (done quickly off top of head):
Assuming 2000 pounds, spread over 5 joists, that is only 400 pounds per joist.
Approximating load to be centered 1' from the wall, the force on that slot at 3' out is only 134 pounds.
So not that critical what you do.
(Remember my old opinion, that you could probably even stop the sister-joist at 4' out)

My opinion on what is very important - Make sure the transfer of weight from joists to foundation
is REALLY solid at the wall. Make sure those joists lie on the foundation, and are really beefy there,
and not toe-nailed to a header or something crazy.
 
Mark, thanks for your opinions! I'm also an engineer by training and profession, but not a civ! And even though at one time I could calculate moments of inertia on different cross sections and calculate loads, etc, etc ... that was a long time ago!

The ends of the current joists are in deed sitting on the foundation on one side, and sit on top of a beam at about 10' before carrying on to the other side of the house. I don't know if there is a seam at the beam, as there are "blockers" (or whatever you call them) at the beam. Doing a bit of research (ie Google) I found that those blockers help the joists share some load, so even if I remove them to add sisters at the beam, I'll be adding them back in.

I popped into Lowes to get better casters for my "tank cart" and was checking out pressure treated versus untreated DF 2x8's. They didn't have any treated lumbed in 2x8x10 at the time, but I could see that 2x8x8 were twice the price of 2x8x10 untreated! The price would not deter me because, heck it's part of my house and anything I can do to thwart termites is OK by me.

I think I have the general plan in mind now and I'll update as I go along.

V
 
I usually go with treated as well, for anything near the dirt.
I think it required by code now in your case.
In contact with masonry that is in contact with soil. Not sure if that applies locally though.
 
Here is some good reading on the subject (Aquariums and floors) very interesting.

http://www.cichlid-forum.com/articles/aquarium_weight.php

V
 
JAR said:
That or just slap a post and pier or two under the joist and cut the span in half or thirds.
Many times in order to get another joist in next to the other you may run in to a pipe, some wires insulation, or existing blocking or nailing that make it a PITA.
Click to expand...

At this point I would support you tank with posts and beam.
A 4"x8"x8' placed under the front of your tank with two 4x4 posts at 6 feet apart (at the front corners of your tank under the floor). Dig down and place piers level on firm undisturbed earth(don't overdig and back fill). put blocks just like they did on the other beam at the 10' mark. Get a bag of cement and fill in the gaps around your new piers. You don't have or need to use PT lumber. If you do make sure to use galvanized nails and "Z"primed hardware for your post to beam connections. Also wear a mask when cutting that stuff. It could have a lasting odor of it is used indoors. It is treated with toxic chemicals.
 
OK, I'll explore the post and beam solution as well. I might sister the joists up to the new beam just to use the palm nailer ...

Glad to hear that PT lumber is not needed.

V
 
OK, I've decided to go with the beam/posts.

I went to HD and Lowes to check out some of the preformed concrete piers, they have a bunch including;

- ones with wood embedded and nailed in them
- ones with two metal straps sticking out
- deck blocks with channels in them for decking

The ones with wood on them come in two size, but are basically the same. One thing I noticed is the crappiness of the wood. Little chunks that were nailed to the top, some are split, they don't look very sturdy. Do they need to be? The ones with straps look good, but obviously you wouldn't use jacks with them, just wood columns.

The more I think about this the more I'm leaning towards buying/using the Ellis jacks. If I used a 4x4 post, I can cut it pretty precisely, but then, how do you install it? Do you tack the beam to the joists, then fit in the beam (most likely hammering it in place. Do you set the posts first and tap in the beam after? With the jacks I can see that it is less important, and you don't have to tap anything into place, just adjust the jack to meet the beam. This would require using the "wood topped pier". If using just a cut post, if it's a touch too short, would I just shim it? What is an acceptable shim?

So, lots of questions!

Oh yeah, so I figured that if I'm going to break through the rat proofing anyway, I might as well dig a 12" deep home and pour in a concrete footer. I'm not just going to sit the pre-formed pier on the soil, mostly because I'm on a hill and the soil tends to be damp, and if there isn't a concrete footing, water will seep into the crawlspace. Also, I think it would be "neat" to pour a footing. I mean, if I don't do it for a living, it's neat, if I did it for a living, I'd find the fastest easiest way.

Any pointers or thoughts on the different piers? I couldn't find one that simply had a threaded rod embedded in it, at least not at HD and Lowes.

Thanks!

V
 
If you are pouring a footing, why also use a pre-formed concrete pier?
Just buy the metal post brackets. You sink one end in the concrete as it sets.
The other end screws to the posts.
I like the long ones. About 2 feet. But not cheap.

Not entirely sure what you mean by the threaded rod.
But they probably sell the rod standalone. Just sink part of it in the concrete
as it sets. Like post brackets.

An idea on height:
Shim it in, with shims on bottom, until it is tight. Cut a bit short, so you can use 1/4" shims or so.
Put in lots of screws. (They actually can handle most of the load anyway)
Remove shims, and squish a bit of leftover cement under post, where shim was.
 
I was going to use the preformed pier so that the posts would be elevated a bit. I did think about just using the footing and putting the post right on it, but since the original piers look like that (raised pier) I thought I'd keep it the same, I dunno. This is why I post my idea here, to see if people have better ones, or if my idea is just dumb!

V
 
Makes sense. Good to get the wood away from the dirt, and probably makes it easier to connect.

Wet the pier a bit and lay it on curing concrete, should bond well.

My opinion - go with the piers with metal brackets. Easy to screw to post, no chance of splitting.
 
Vince,
I reinforced our floor for a 90 gal, just in case of the big one. Now I am moving up to a 180 and have no worries. I also ran some new wireing while I was down there and installed GFI outlets.
Good Luck
Kelly
 
rygh said:
Makes sense. Good to get the wood away from the dirt, and probably makes it easier to connect.

Wet the pier a bit and lay it on curing concrete, should bond well.

My opinion - go with the piers with metal brackets. Easy to screw to post, no chance of splitting.
Click to expand...

+1
 
IT HAS BEGUN!

OK, I'll post a few pics when I get home, but I finally started!

I sloppily marked out where I wanted the holes, trying to center the eventual post locations to coincide roughly with the corners of the tank, though in reality I'm sure they won't line up. Also, I didn't center the posts such that they sat directly under joists. I'm not sure if that's important, since the beam will span the tank and some extra joists. I used my kids "driveway chalk" to mark the locations, it was tough because there was a lot of dust on the floor and I didn't think enough to brush it away.

In retrospect a diamond blade for my circular saw would have been cleaner, but I used my Harbour Freight (yes, ha ha) rotary hammer with a cheapo HF 3/4" bit and perforated the rat-proofing (about 60 holes or more per hole!) Then smacked the middle with a sledge hammer to break it up. I gotta say, that rotary hammer is awesome! (obviously not as awesome as a non-HF rotary hammer, but pretty awesome for someone who doesn't drill concrete for a living!). It was stubby enough that I could get it vertical over one of the holes that is a bit cramped (due to the uneven contour of the crawlspace floor). It was fast going, took less than 10 minutes to perforate and smack each hole.

The "rat proofing" was about 1 inch or so thick, with a layer of sand and 1" gravel under it.

Using a "mattock" like tool and a stubby shovel (harbour freight!) and a gardening trowel, I managed to dig out the 16x16x9 holes. Though some of the 9" depth is really not in soil, but extends up to the gravel/ratproofing layer. So the actual soild depth is more lik 7 inches. But honestly, I'm done with digging... ugh! It was pretty painful. Also one of the holes has a giant rock dead center at the bottom. I'm not sure how that will affect the footing when I pour it. Lugging the damp clay and broken concrete out of the crawlspace (I used a mixing tray to move the debris) reminded me of "The Great Escape". Luckily I have a neighbour doing construction and I snuck some of the dirt/debris into his debris box. I had earlier asked him if I could throw some old insulation in there, he said sure, but I didn't pull any insulation, so I think I'm still not a bastard for sneaking the dirt in there.

I even bought some rebar. I was too lazy to buy the 4 foot piece and cut it, so I spent an extra buck and bought four 1 foot pieces. And I bought two 2" dobies to sit the rebar on (in an X shape). I'm not sure it this was necessary, but what the heck. The dobies were cheap but in retrospect I could have just put a bit of concrete in a yogurt cup and let it cure for a day to make my own dobies. But I'm not THAT cheap.

I had a small window to do this as Sandy took the kids to the zoo so that I could have some time to use the rotary hammer while they were not at home sleeping. (I can do most of the rest of this while they are in bed in the evening, but it would be impossible to hammer/drill the rat proofing while they slept. I gotta tell you, I can't imagine a rat could make it that far under the crawlspace.

The "soil" was damp clay, it was actually easy digging, which worries me a bit, and there were rocks in it. One hole had pretty big ones (fist sized).

Man, that was HARD WORK! It wasn't fun, but it was supremely satisfying!

Next step will be the concrete mixing and pouring. It will be great fun to haul four 80 lb bags of concrete mix into the crawlspace. In retrospect I should have bought 60 pound bags, I couldn't find any 40 pound bags.

But I've finally acted on this plan, so that makes me happy!

Pics to follow!

V
 
OK, some pics!

The perforated outline. I punched about 60 holes with the HF rotary hammer. In retrospect a diamond edge circular saw blade might have saved ALOT of time, but I had no idea how deep the ratproofing was. So I decide to go the brute force way ... drill holes then HULK SMASH!





From 180 Gallon Aquarium



Hulk Smash!





From 180 Gallon Aquarium



Start digging, that harbour frieght stubby shovel was great. A short garden hoe helped too





From 180 Gallon Aquarium



Setting up some rebar on a dobie





From 180 Gallon Aquarium

The pier






From 180 Gallon Aquarium

Dobie and rebar in the concrete. Dobie was a waste of money (50 cents though) as the bars were not going anywhere.







From 180 Gallon Aquarium

The whole shebang






From 180 Gallon Aquarium

I've now placed some wet towels and plastic sheeting over the footing part to help the concrete cure.

I'm not sure if I screwed up the concrete. I followed the directions on the 80lb bag of mix and added 3/4 gallon (3 quarts) of water per bag. I added a touch more water (and extra 1/2 quart) because it was more like lumpy dry oatmeal than anything that would "pour". In anycase I'm not redoing it so it better work.

Now to let it cure and add some electrical work while I wait. I have the 4x8 beam (overkill?) and 4x4 posts in the garage.

Man that was some seriously exhausting, cramped uncomfortable work!

Vince
 
It's worse than you think ...

This is where it was done;





From 180 Gallon Aquarium

The hammer was short but heavy (4 lbs). The handle is long enough to get one hand on it. I took short stupid swings.

It is exhausting because it's SOO GROSS DOWN THERE that I wore a respirator all the time, and used goggles and a "bump cap". I was wearing coveralls at first with knee pads over it. I was drenched in sweat all the time. It sucked big time, but the hard labour part is mostly done.

Since Sandy took the kids to the park on Sunday, I went back down there with my "Simpson UFP10" plates and started doing some earthquake retrofit there too. That means I went right up into that corner there (in the picture) and installed two plates there, 12 inches from the corner. It must be 2 feet tall there. I'm glad my day job is software! I'll take pics of the retrofit stuff and post it in the other thread on that topic, the next time I'm down there.

I tell you, that Harbour Freight rotary hammer is an awesome tool. And at a fraction of the "big name" tools. It's already paid for itself.

I think I'm actually going to wire up some lights under there, it's not as bad if it's bright. And I'll get some cheapo harbour freight tarps to lay down on that filthy disgusting crawlspace floor. I was going to do another wall, but that meant going near where the dead rat was (that I removed a month ago). Luckily the kids came back from the park, giving me an excuse to stop being in the crawlspace. My whole ancient body hurts.

Vince
 
Wow, brutal amount of work, but really looks solid to me!

For crawlspace lights, consider the low voltage yard lights. Might be easier and safer, although not as bright.
Looks like you could use some insulation under there as well.

Fun suggestion: "Test" the new tank in the garage. Add tap water, heat to about 100 deg, and add lots of powerheads.
Might make the aches and pains go away.
:)
 
Vincerama2 said:
It's worse than you think ...
......
It is exhausting because it's SOO GROSS DOWN THERE that I wore a respirator all the time, and used goggles and a "bump cap". I was wearing coveralls at first with knee pads over it. I was drenched in sweat all the time. It sucked big time, but the hard labour part is mostly done.
......
Vince
Click to expand...

SOO GROSS?? I wish mine is half as clean as that... :(
IMG_4345.JPG
 
Wow, speak of the devil, 3.8 quake in Pacifica a few minutes ago! I spent yesterday installing foundation plates, and only got halfway done.

I'm doing quake retrofits while I wait for my footings to cure before adding the posts/beams.


V
 
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