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Reinforcing floor for large tank?

OK, here is what I have now. There is a problem though...the joists are not all even. The beam is very straight, I even used a laser-level to check it, and I used a straight 2x4 to confirm the uneven-ness of the joists.

I asked about this on a DIY forum, some people said "Jack up that beam and force the low beam up 1/8"" I will try this, but I don't want to warp my 70 year old floor! Another solution was to mark and then notch the beam itself. And the last was to shim with wood or metal (metal preferred) but this solution is was frowned upon by some people and others said it was fine.

I had cut some slices of my 4x4 post to use as shims, but I also went to HD and bought a piece of steel to cut as shims. I don't want to mark and notch the beam as it's freaking hard to move that beam around as it is. I will try the beam jacking first to see if it might make some of the joists fit better. of course if it kicks my floor out of level, I'll not do that and just shim.

So the bottom line is, with the beam on straight, there are gaps at 4 of the 6 joists that it spans. 1/8", 0, 1/8", 1/4", 1/8", 0.
The beam is NOT sagging.

Here's a pic. Notice the shims! The leftmost joist is also gapping at 1/8". I have not nailed the metal hardware to the wood yet. The posts are vertical, the metal straps are NOT vertical.





From 180 Gallon Aquarium



Here is my laser level, showing that the beam is straight;







From 180 Gallon Aquarium

So close!

V

Oops, where is my pictures!
 
before you go jacking the floor up (I can very well see you warping the floor, double check on the floor first to see if it's level on the inside :D)... you might want to measure each joist, 70 year old lumber might not be cut exactly the same, and it's simply one is a 16th wider or something.

Either way my solution would be to shim up the 4x4 and make it fit that way.
 
The problem is not that the 4x4 is not tall enough, the joists above the 4x4 posts are TOUCHING the beam. It's .. I dunno, weird 70 year old construction. I don't want to jack up the floor for fear of breaking anything (plaster, floor, etc!). Each joist, as far as I can tell is about 7-5/8". The subfloor seems tight up against it. Just weird.

I'm going to measure where the joists are. If I measured stupidly the first time, it's very possible that the offending joist is sitting under a wall that separates the dining room and the kitchen. That would explain the dip, but also means that I put the beam over a bit too much in one direction, not too bad because it's an 8 foot beam and the tank is 6 feet long, to be placed about 1 foot or so from the that wall. So the tank should still be covered by the beam. If this is the case, then jacking that beam will probably crack the plaster! I didn't even think about this until I started writing this post!

I bought a 3 foot piece of 2" wide by 3/16" steel flat. After seeing if slight jacking does anything on that one side, I'm going to cut the flat into shims. I bought some rustoleum spray paint that says "protective paint" or something to prevent the shims from rusting (hey, they'll be under my "leak proof" aquarium, right?

V
 
I checked the floor, the slightly lower joist is right next to the wall.

I really planned it out poorly. Now that I know what I'm looking at, I see that the beam starts IN THE OTHER ROOM. So I have to shift the whole thing over to cover the correct joists! Luckily, the beam is long enough to do so without having to canilever more than one joist.

But It was really hard to get a point of reference other than by tape-measure .... until I finally noticed the nails sticking down that indicated where the non-load bearing wall (kitchen/dining room) was!

So I'm NOT going to jack up that joist because it will most certainly crack the wall plaster (more than it is now I mean!)

V
 
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