I am hoping to put a 220ish gallon peninsula reef tank in the center of a room. Unfortunately that means it will run parallel with the floor joists. The joists are 2"x4"x10" floor trusses, 24" OC, with a 13' span. I know absolutely nothing about these and finding information on them is proving to be difficult. The tank dimensions are 72"x30"x25". (May go to 27" tall but well see). I would make sure the tank spans 2 joists. I have thought about either putting 4 jack posts at each corner of the tank. Or trying to sister each with a 2x10 on each side of the truss. The room is above a crawl space so I rather do the jack posts as I feel it will be easier. Any input or terms to search would be greatly appreciated.
Floor trusses
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William Mumford
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The jack posts is my suggestion if you can be at the 4 corners you should be golden.
MichaelReefer
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Personally, as an over-cautious person, I would put some extra ones in there so if one does fail you dont get a nice hole in the floor. Just my opinion.
William Mumford
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You are 100% right Even better. I like 1 on each corner and 1 in the middle so 6 total
I would add make sure the jack posts are on the proper footer, otherwise the weight will cause them to sink over time. If the tank were on the wall that is one thing but being on the center the floor is probably only rated to 50 lb / sq foot or so as is. Friend had a floor sink 1 inch to the one side with a 220 and had to drain. You are basically putting a car in a small footprint on a wood floor so want to take the necessary precautions.
Thanks for the replies!
0 My worry about the jack posts was needing a proper footer. And with 2' of room digging down and pouring concrete isn't really an option. I also realized I can't sister the whole span since there's HVAC in the way. Would a hybrid option be best? Sister as much as I can with 6 jack posts underneath. Hopefully that wouldn't put too much stress on the concrete and allow me to sleep at night.
0 My worry about the jack posts was needing a proper footer. And with 2' of room digging down and pouring concrete isn't really an option. I also realized I can't sister the whole span since there's HVAC in the way. Would a hybrid option be best? Sister as much as I can with 6 jack posts underneath. Hopefully that wouldn't put too much stress on the concrete and allow me to sleep at night.
Jack posts do not do much unless they are on solid footer / base. If they are not on a solid base they are not helping and will only sink under the weight potentially uneven as well depending on what each is sitting on. Putting them on something like a paver stone to spread out the weight does risk the paver stone splitting in half under the load. If you can get under to sister the span then it seems there is possibly enough room to add the footers as well although it would not be fun either way.
I am not sure how that is determined just by looking at them. A new residential floor today is designed with a live load of 40-50 lb/sq ft. New housing construction just does not throw more money at it for the heck of it, they often design to the bare minimum. If the trusses are marked one could look online to confirm. The longer the span the more deflection in the center. We are talking a small SUV placed in the center of a room with a footprint of 10 sq. ft or so, in excess of 300 lb/sq ft possibly.
A concrete footer from home depot would be enough to prevent sinking in the soil. The tank is NOT going to fall through the floor... but your joists could bow over time.
You dont need jack posts in the middle of the truss... you would effectively making a 6' span with jack studs on the ends.
You dont need jack posts in the middle of the truss... you would effectively making a 6' span with jack studs on the ends.
Can say that because I know. When you look at a big blob of weight in the span of a given length it’s not the square footage weight, it’s the deflection limit. Am familiar with that style tress and after plywood would strap the center 2x4 against the lengths to in affect act as floor joist cross brace. The floor can hold the weight, it’s a matter of how much it moves/deflection limit.
If you want or need to add a jack post that would go under the newly installed 2x4 cross brace.
if It where me I would just build A couple 2x6 walls under it. You could one on each side the length of the tank. Build it from the plywood to the concrete. Not under the joist. By doing so you will evenly distributed the weight on the concrete floor.
bluprntguy
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Well, I’m an architect, not a structural engineer. But IMO, you’d be better installing a glulam (good) or steel beam (better) under the tank, between the existing joists and resting on those existing concrete walls. Those joists are strong, but there tends to be significant deflection, especially when point loads (like a heavy tank) are added.
13’ isn’t a significant span for either glulam or steel and then you wouldn’t need to deal with Jack studs in the center unless you really wanted to go overkill.
13’ isn’t a significant span for either glulam or steel and then you wouldn’t need to deal with Jack studs in the center unless you really wanted to go overkill.
Joekovar
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I'm thinking 1/4" x 24" x 24" steel plates for footers. The feet on arms that drop to stabilize backhoes and cranes come to mind.
On top of those, post Jack's. If by true center of the room, 4 Jack's and 4 footers. If centered on a wall that's on top of the pictures block footer, 2 Jack's and 2 footers.
For each pair of footers, run an 8' long 4" x 4" beam perpendicular to the joists, at the top of the upside down pyramid so it spans 4 joists and sits close to the corners of the tank. Hold the beam up with the 2 Jack's on the inside of the 2 middle spanned joists.
On top of those, post Jack's. If by true center of the room, 4 Jack's and 4 footers. If centered on a wall that's on top of the pictures block footer, 2 Jack's and 2 footers.
For each pair of footers, run an 8' long 4" x 4" beam perpendicular to the joists, at the top of the upside down pyramid so it spans 4 joists and sits close to the corners of the tank. Hold the beam up with the 2 Jack's on the inside of the 2 middle spanned joists.
Difference between an architect and an engineer.. one know deflection and load limit tables.
Just fill your entire crawlspace with concrete...can never be too safe
Just fill your entire crawlspace with concrete...can never be too safe
I would not expect the floor to fail but there are differences. The 220 my engineer friend had ended up seeing that floor deflection to the point where there was a gap along his baseboard and the one end of the tank was low about an inch. Sure the architect that designed his floor would say no worries, the floor will not fail. The engineer in him did not want his tank unlevel to the point it was visible plus all the added mechanical stress on the seams.
ca1ore
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Jack posts under the four corners is the way I would go. How compacted the ground is in the crawl space will determine whether you need to worry about the posts digging in. If it’s well compacted a small metal or even plywood plate will distribute the weight. That’s what I did in my tank and the plywood plate hasn’t settled into the ground at all. If the ground is not compacted, then settling is a potential problem. I’d just sink a couple of cinder blocks in that case.
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