Is my floor sufficient for a 260 gallon?

[Tuffloud1]

I just got finished reinforcing my floor before filling my tank to leak test it.

The floor joists are 2x6, 16 OC.

The back of the tank backs up to a load bearing stem wall.

I added a 7 foot 4x6 beam which are supported by 3 floor jacks on concrete piers which I dug down a foot and poured concrete. The pre fab piers were placed on top of the 1 foot deep footing.

This 4x6 beam is running along underneath the front of the tank.

Tank is 72x28x30

Is this sufficient?

 

[Blitheran]

One thing I always like to say is, i’d rather be safe then sorry

 

[ndrwater]

You're fine. Nice job by the way..

 

[Tuffloud1]

My concern was that my floor is constructed using 2x6 rather than 2x8 or 2x10.

The front of the tank sits slightly short of being directly over the 4x6 I added. Maybe 1-2 inches short of it.

The back of the tank sits slightly short of being directly over the stem wall. Maybe a couple inches short.

 

[ndrwater]

Still good. Load is distributed down to the piers. Not being exactly under the edge of the tank isn't an issue in this scenario.

 

[Tuffloud1]

Still good. Load is distributed down to the piers. Not being exactly under the edge of the tank isn't an issue in this scenario.

Awesome!

I hear a lot of people “blocking” their joists to add strength. I did add some type of metal hangers that attach the joists to the beam on a few of the joists but not all.

Do you think I need to block between all the joists?

 

[Tuffloud1]

And the only other concern I had was I couldn’t get one of my end footings close enough to the last floor joist so the beam overhangs the last pier in order to be underneath that last joist.

Is this a problem? See picture

 

[ndrwater]

Blocking prevents lateral movement and twisting. Doesn't hurt in this case, but probably overkill.
As for the last pier being inboard of the end if the 4x4, also shouldn't be an issue. The load is still transfered. If you are really concerned, when adding water to the tank, have a level on the floor at the overhanging joist/4x4 area. If it starts to sag more than the rest of the supported area (highly doubtful) stop filling and go to plan "B". The only real concern here would be uneven sag. As I mentioned above, highly doubtful that that happens.

 

[Tuffloud1]

Last question.

How tight should the post jacks be screwed?

I tightened them just before I saw the joists being pushed upward.

So they are pretty tight.

 

[ndrwater]

Just following up on this a bit and a point of reference. Many of the 2x4, 2x6, etc stands you see built here and on other sites will not only hold the tank, but the builders car as well. Definitely overkill 99.9% of the time.
If i were to make a suggestion, make sure the grain in the 4x4 is running vertical. Meaning that the grain is facing the tank above. Wood is extremely strong against the grain. If the grain were to be horizontal, or "on the flat" it is less structural. With a 4x4, the grain is probably circular because they cut 4ish inch trees into 4x4s. In this case, make the crown or bow in the wood, If any, facing the tank. Meaning up. The weight of the tank will compress the bow to straight(er) increasing strength

 

[ndrwater]

Last question.

How tight should the post jacks be screwed?

I tightened them just before I saw the joists being pushed upward.

So they are pretty tight.

You did it correctly. There may be some slight settling, but as long as it is consistent along the length of the tank, all is right with the world.

 

[Tuffloud1]

Just following up on this a bit and a point of reference. Many of the 2x4, 2x6, etc stands you see built here and on other sites will not only hold the tank, but the builders car as well. Definitely overkill 99.9% of the time.
If i were to make a suggestion, make sure the grain in the 4x4 is running vertical. Meaning that the grain is facing the tank above. Wood is extremely strong against the grain. If the grain were to be horizontal, or "on the flat" it is less structural. With a 4x4, the grain is probably circular because they cut 4ish inch trees into 4x4s. In this case, make the crown or bow in the wood, If any, facing the tank. Meaning up. The weight of the tank will compress the bow to straight(er) increasing strength

Thanks for all the info.

The beam I installed is a 4x6, not a 4x4.

Not sure if you were referring to something else.

I did make sure the crown was facing up on the 4x6.

 

[ndrwater]

A

Thanks for all the info.

The beam I installed is a 4x6, not a 4x4.

Not sure if you were referring to something else.

I misstated. 4x6 is even better. The crown/grain comments still apply though.

 

[Tuffloud1]

A

I misstated. 4x6 is even better. The crown/grain comments still apply though.

Yep, I crowned the 4x6.

Thanks again bud!

 

[ndrwater]

Make a build thread!! Many a new reefer have the same questions as you do and would benefit from your experience. PLUS, you'll get a cool banner by your name!

 

[Tuffloud1]

Make a build thread!! Many a new reefer have the same questions as you do and would benefit from your experience. PLUS, you'll get a cool banner by your name!

I am definitely going to do that!

 

[ndrwater]

I am definitely going to do that!

When you do, include all the pix above and the concerns you had. Definitely would be helpful to others in a similar situation. You did it absolutely correctly and could mentor others in the future.
I look forward to your thread!!

 

[Beau_B]

FYI, blocking is generally done for live load performance, what you may experience as bounce or vibration as something moves across a floor system. Your tank is a dead load, being constant. In that case you are mostly concerned with the timbers sagging or deforming over time. The beam you've put in eliminates any span concerns (the need for larger dimensional joists) at this point it could be 2x4s and you would be fine.

If you have any remaining concerns about anything it should be that the 2x6 would deform as a result of point loading. The area where the 4x6 and the bottom of the 2x6 meet is a small contact point and the 2x6 along it's width doesn't have good compression strength. To combat this you could add squash blocks, which are simply chunks of 2x set vertically to increase the compression resistence. In your case it would be 2x4 in 5.5" lengths glued and fastened to the 2x6 on one or both sides where it rests on the 4x6.

Most 2x dimensional lumber rates around 500psf for perpendicular compression. You would have to do the math on total load vs bearing points but I'm guessing it's a non-issue.

 

[ca1ore]

The only thing I would 'worry' about would be the 4x6 twisting. When I reinforced my floor (for a much larger tank than 260), I used homemade plywood micro-lams. They wont warp or twist.

 

[Tuffloud1]

I guess I should have asked this as well.

Is a 2x8 sufficient for the stand header frame? 260 gallons with no center back support.

This was a premium piece of lumber that I searched 3 lumber yards before finding it. It had absolutely no knots in it and 0 twisting. It was also completely dry.

Span is 64 inches between supports.