Jacks under floor...

S

suprzman

Member
Hey everybody,
Does anyone know the name, have pictures, or can refer me to a website link for jacks I can put under the floor, where a slightly heavy tank is to be placed? I want to put some support on the beams of my first floor by laying a square of wood up against them, and having a jack or two underneath...
Havent been able to find a picture or anything on home depot or loews websites yet...
Thanks,
Z.
 
They are called lolly columns. They are steel posts that usually have the foot connected to a threaded rod that can be adjusted to the hieght needed. You can usually get them at a masonry supply place as they are installed in the concrete floors of basements. However, you can really just use a 4x4 if you like. Cut it to just the right length and bang it into place.
 
that would be lally column :)

Before you go jacking yoru floor up... how big of a tank are you talking? You can cause as many (or more) problems than you fix in some cases.
 
BeanAnimal, could you elaborate a little more on "causing more
problems than you fix" by bracing the floor?
 
I used some jack posts under my 120 tank. they where put in to secure the floor not raise it up. My goal was to ensure that when the 1000+ lbs of tank was on the floor that it did not sink any. Therefore, the jacks where put in snug.

Here was the plan that I used.

foundation.jpg
 
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I would like to know how you can make it worse by reinforcing your floor as well. I am putting a 90 in a room with quite a bit of give in the floor, & I need to reinfoce & stabilize it before I put a ton of deadweight in it, on top of what is already there. How can you make thigns worse?
 
Firstly, if you support the tank with jacks, you are changing the load design of the floor. This may or may not pose a problem, but it was certainly not part of the load plan. This can shift other loads on the floor to your jacks, not their rintended bearing surface. This can leave a very uneven floor surface (check out any old house where beams and jacks have been used to re-support the floor).

You may run into problems with different types of supports. Wood "beams" expand and contract with seasonal changes, as does the ground itself. This again may or may not be a problem depending on the location of the tank and the climate or crawlspace conditions.

Posts or "pads" that sink slowely over time can cause a tremendous amount of stress to build up in the stand and/or tank. Remember you may have unwittingly transfered the entire living space load right on to your jacks, not just the tanks.

In most cases with most modest sized tanks, extra support is not needed. Most floors are engineered for a lot larger static (dead) load then your tank will pose.

Are you putting in a 300 gallon tank or a 125 gallon tank?

Without the details, including tank size, location, floor layout, joist size, etc... it is hard to tell if you need extra support or not, but as already stated, most modest size tanks put on a proplerly built floor will be just fine.

BTW, your floow is supposed to flex, that is why it is strong and able to carry heavy loads. Ever notice the floor in a mall "move" or a bridge bounce when you are stopped on it?

Bean
 
I would have to disagree that most floors are engineered for a lot larger static load than a tank will pose. If the load was spread out across the whole floor maybe. Not the 300 lb / sq foot in a small area. I have seen too many houses not using 2x10's for flooring and they bounce when you walk on them. There are too many variables to blindly say that most floors are designed to handle the load including load bearing walls, joist spacing, direction etc. We get away with a lot but I would not say it they were all designed to handle it.
 
300 LB a square foot?

Lets take a 180 gallon tank:

Footprint 27" X 72" = 12 sq feet
180 * 8.330 = 1500 lbs
ROCK = 500 lbs
Tank and stand = 200 lbs

that is 2200 LBS worst case, remember that the rock will dsplace a lot of the water (more than fits in the sump). The actual weight will end up at about 10 lbs per rated gallon of the system.

In any case lets use 2200. That comes out to about 180 LBS per square foot (more like 150 in reality). A far cry from 300. Did you ever notice that when the build houses, they drop pallets of plywood, shingles, drywall and other HEAVY loads right onto the floor decking? Did you ever ponder what a skid of drywall weighs, they don't sit flat, they sit on 3 2x4 planks (less than 2 square feet of load distribution).

No matter what "they use", all modern homes must design the floor using span tables or other proven engineering, older homes are commonly over built. Are they houses with 2x6 joists on 24" centers that span 16 foot load bearing walls? I am sure there are.... but then again I said "in most cases" you should be ok.

There is a great article someplace that covers this entire subject from a techincal point of view and how it relates to most tanks and most floor. I will try to find it.

again, a bouncing floor is not such a bad thing. Deflection is better than "failure", not to mention that much of the data in a "span" table is geared towards defelction for reasons other than safety. A common design goal is no more 1/3" deflection for spaces above a finished area with a drywall cieling. 1/3" should not cause the drywall to crack or spall, anything more may.

In any case before we get into a debate about what is safe and what needs supported, lets get the details of the OPs tank, floor and other variables.
 
The room that my tank will be in was once a family room, that sat a few feet lower than the rest of the home. When my wifes grandfather had cancer, we remodeled the room to bring it up level with the rest of the house & made it a bedroom/bathroom for him. After he passed, it was the kids playroom, then a junk romm, & now its a computer room for me & a sewing room for my wife. It also houses a 90 gallon tank that is chock full of supplies, for the day that it is finally filled with water. heh

When my kids (4 & 5) run thru the room, it shakes like crazy. The tank will straddle a few of the joists, & it sits againtst hte wall, where they built the supports for the raised floor. I am not comfortable leaving it with no reinforcement. I am not comfortable with the amount it gives as is. My thought was to try to mimic what Patt did in their diagram. The floor that the supports will rest on is concrete. I was going to push the jackstands up to squeeze a piece of wood between them, & the floor. Not too hard, but enough to tranfer some weight into the floor.
 
Beananimal,
It is not meant to be a debate. My 120 reef was about 230 lb / sq ft counting the sump, canopy and lights so the 300 figure was a little high. At typical new construction is designed for a live load of about 40 lb / sq foot EVENLY distributed across the floor. The key is evenly distributed. Our tanks are more concentrated so the effect is worse as the load is not spread over all the floor joists. I was involved in the construction of my house and they did drop pallets of shingles and drywall on the second floor with a crane. With a partial pallet of shingles I would estimate the floor flexed at least 1 inch, I am sure well passed it's design. You just sat and watched the floor sink and this was 2x10's with 16" OC and a 12 foot span using 3/4" plywood. I would not walk under it and neither would anyone else. Are we talking about what a floor can handle before structural failure or what it is designed for? The 2 are much different. A 10X12 foot room in this case could handle 4800 lbs evenly distributed. A tank concentrated on a few of the close joists and I bet it exceeds the rating even though you do not have anywhere near the total room load capability. Put 2000 lbs in the center of a room (and joists) vs. against a load bearing wall vs. 17 lb /sq ft evenly distributed over a 10x 12 room and they are not the same and will all give different deflections of the floor. I would be very much interested in the article you mention.
 
Wow. Didnt expect this many responses.

BeanAnimal, the tank I was thinking of installing is a 120 gallon tank. Though its small compared to some of the tanks that are put up, like 300, 400, or 500 gallon tanks, it will still put more than a 1000 pound load on the floor. If the weight was distributed over the entire floor of the room, it would not be a concern, but I think its weight would be concentrated to where it is placed.

What I dont understand is how adding the jackposts would compromise the stability of the rest of the structure of the house? I agree that it could possibly transfer the weight of some of the other objects in the room onto the columns. But if I used an 4' - 8' post, that would be roughly a 9000 - 18000 pound weight bearing capacity. With a 1000 pound tank, there is not too much of a risk of overwhelming the lally column. With regards to the weight of the walls, they would still be transferring their weight vertically onto the foundations of the house.

It makes sense that an old house with beams and jacks would have an uneven floor surface, but only if the floor wasnt supported evenly. In the case of my house, however, the floor is not sagging in any place. So the placement of one beam, directly under a large weight, should not have any effect on the integrity of the rest of the floor.

Z.
 
Brian, I am not sure what there is no debate? Is it because you feel that your are 100% correct?

Surely you see where you have made my point? The love load rating of 40 psf really has nothing to do with what we are talking about here. A dead load in a stationary position does not equate well to a "live load" calculation. The point remains the same, most structures will not show any significant deflection with a modest size tank ( for our purposes 180 or less). The load surely does not come close to any failure mode or present a danger to anybody walking under it. The need for extra support is further lessened when the load is abbuting or near the load bearing surface, as the deflection will be even less.
 
Bean,
I see you do not have a background in engineering, structural in particular. A dead load is worse on a floor than live and is typically the worst case. You would have to reduce the live rating even more since it is stationary. See the above link. The live load rating does relate to the construction of the floor and absolutely effects what we are talking about here. Where is you link discussing these issues as mentioned. I would be curious it in it anyone has some credability. Reef Central is full of experts - just ask them. Will the floor fail - most likely no. Will it exceed it's design deflection and crack some drywall etc. - possibly.
 
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