Floor support: Add joists or new beam and post? 200 gallon

The Coug

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I’ve started working on my new tank and I need to decide how to support the weight. The tank is a custom 5ft x 2.5 ft peninsula that will stick out into the middle of a our former guest room. The tank will sit perpendicular to the floor joists with the overflow end adjacent to the concrete foundation wall leading into the garage (sump, fuge, etc to be plumbed through wall into the garage).

So, I want to add some support in the crawl space for the tank. The floor joists are 2x10s spanning the 12 ft between beams. On the far end, the joists are attached to the beams via joist hangers. On the near end the cross over top of the beam, extending another 2 to five feet to the outside sill plate.


Option 1. Add 3 new 12 foot joists to sister to the existing joists. I probably couldn’t truly sister them since they are on joist hangers on one side so I’d just add 3 joists to put one every 8 inches instead of 16.

Option 2. Install a 4x8 beam under the center of the tank perpendicular to the joists supporting it with a 4x4 on a poured concrete pad.

Any thoughts on which would be best.

Pictures:
1. Red markings are roughly dimensions of tank position.
2. Beam with joist hangers
3. Beam that joists could sit above
4. Room where tank will sit. (Tank in red).

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mb5322

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I'm certainly no contractor, but I have spent 20 years in construction. In my opinion if you wanted the option that you never hesitate about or even think about again, its going to be pouring concrete and the 4x8. You and I both know its the more intense option, but we also know if done this way you will never question the integrity of the floor.
 
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The Coug

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I'm certainly no contractor, but I have spent 20 years in construction. In my opinion if you wanted the option that you never hesitate about or even think about again, its going to be pouring concrete and the 4x8. You and I both know its the more intense option, but we also know if done this way you will never question the integrity of the floor.
Thanks, I was actually thinking the post/beam might be the easier option. I won’t have to deal with cutting insulation or have to figure out a way to angle in the 12ft joists into the crawl space. It will involve some digging though. You think it’s the stronger option though?
 

mb5322

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Thanks, I was actually thinking the post/beam might be the easier option. I won’t have to deal with cutting insulation or have to figure out a way to angle in the 12ft joists into the crawl space. It will involve some digging though. You think it’s the stronger option though?
myself personally if I never wanted to think about it again, and be able to park a semi truck on it, I would outline the tank in 4x4, in the crawl space then put house jacker? I can't remember the exact name of them, but you see them in old basements, heavy pipes that you unscrew for joist support. I will find the exact name of them for you and put one of those every other joist, with the poured concrete as bottom support. but then again I tend to way overdue things out of an abundance of caution.

found em, joist support jacks. Amazon.com: BISupply Basement Floor Jacks – 36in Adjustable House Jacks for Leveling, Basement Jack Post Floor Joist Jacks: Home Improvement the come in all sized, weights and price ranges.
 

mb5322

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Thanks, I was actually thinking the post/beam might be the easier option. I won’t have to deal with cutting insulation or have to figure out a way to angle in the 12ft joists into the crawl space. It will involve some digging though. You think it’s the stronger option though?
And yes I think this is the stronger option
 

ca1ore

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Both options seem like a lot of work. Go to HD (or an equivalent store) and buy four jack posts. Put one as close to each of the four tank corners as you can. That’s what I did for my 450.
 
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The Coug

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I was looking at jack posts a while ago but the maintenance kind of scared me off. They do seem lots better than a 4x4 post though since you can adjust them into position instead of shimming or just jamming it under.
 
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The Coug

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myself personally if I never wanted to think about it again, and be able to park a semi truck on it, I would outline the tank in 4x4, in the crawl space then put house jacker? I can't remember the exact name of them, but you see them in old basements, heavy pipes that you unscrew for joist support. I will find the exact name of them for you and put one of those every other joist, with the poured concrete as bottom support. but then again I tend to way overdue things out of an abundance of caution.

found em, joist support jacks. Amazon.com: BISupply Basement Floor Jacks – 36in Adjustable House Jacks for Leveling, Basement Jack Post Floor Joist Jacks: Home Improvement the come in all sized, weights and price ranges.
Thank you!
 
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The Coug

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There is no maintenance of the post Jack's. They are mechanical screw adjusted, once in place on a secure footing and adjusted tight you are done
Fantastic! I remember reading at somepoint that you have to check the hydraulic fluid or something in them. Those ones on Amazon look great although it says not for permeant use on the bottom. I think I’ll try to see if there are any out there recommended for the long term. It seems like they should last longer than the wood posts supporting my house??
 

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I used jack posts and pressure treated 2x6’s. I also painted and trimmed out a piece of 3/4 cabinet grade plywood to sit under the stand. This not only helps distribute the weight on the top of the floor but also helps to protect my hardwood floors from small spills that will happen. My tank is only about 130 gallons total volume but my home was built in the 50s and the floor was a little spongey, tank is rock solid after.
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