Reinforcing floor for large tank?

Discussion in 'Equipment' started by Vincerama2, Feb 18, 2011.

  1. Vincerama2

    Vincerama2 Evil Overlord

    My wife inadvertantly gave me the go-ahead to upgrade my tank and I have an eye on a 180 that someone is selling on RC. I'm a bit worried about weight on the floor though.

    Did you guys with big tanks re-inforce the floors? I'm considering it because when my sister had a GIANT bathtub installed in her house, the construction guys re-inforced the floor for it.

    Seems pretty simple actually, sandwich the floor joists with 3/4" plywood on either side (of each joist). It apparently increases the strength of the floor by a factor of 6. I'd probably "torsion box" the joists too, by attaching plywood to the bottom of the joists. Plus the floor itself is 3/4" oak.

    Naturally before putting the tank in, I'll give that section of the floor a few extra coats of polyurethane to help defend it from spills.

    I'm not TOO worried because ... it's a FLOOR, BUT 180g x 8 lb/gallon = 1440 lbs. That's 7 fat guys standing around. Not to mention sump/stand/rocks, etc.

    So what do you think? Giant tank = need for floor reinforcement, or am I just paranoid?

    Oh yeah, my house is one story, and I have easy access to the crawlspace, so I don't have to rip up any ceilings or anything.

  2. Vince, I did it and it would probably be a good idea, if nothing more than for peace of mind. I've yet to load the floor, but the joists were sistered on both sides with 2x6 over a 6' x 10' area just in case. I also had the contractor do the work during the remodel so not only are we covered against potential sagging issues but the whole thing was engineered by a professional and thus hopefully will keep me alive should something unfortunte happen!
  3. rygh

    rygh Supporting Member

    If easy, I would recommend it. Mostly because you never really know how well they built the house originally.
    Key is to look at exactly how the floor joists are connected.
    Sometimes the weak point is at the wall/header, not the joist itself.
    So if you have that weight, plus a party with a lot of people standing around it, it can pull the joist out.
    Especially if tank is parallel to joists.

    Given 1 floor house and a crawl space, consider a post or two underneath.
    1) Put a large 4x6 or so, crosswise, under the existing floor joists, where tank will sit.
    2) Put a column or two 4x4 down from that, into concrete, into the ground.
    So basically, you add direct compression support from ground to floor.
    Exact design will depend on orientation between tank and floor joists.
  4. Vincerama2

    Vincerama2 Evil Overlord

    Fingerwrinkles: Off topic, but I finally put the girls' beds together, that took a whole day since I had all the pieces jumbled up and had no idea which bed was which and what they looked at! Also, my wife keeps questioning me about why I don't try to keep the clown hatchlings alive! Another project for another day!

    rygh: Thanks for the tip, I will do that. Would you put the 4x6 "on edge" so that the weight is on the edge, or the face? I'm guessing edge.
    There is "rat proofing" under the crawlspace, which is also unfortunately not flat (it sort of follows the contour of the ground rather than having been leveled. However, It won't be too hard to break it up and sink a concrete footer or two. Instead of pouring a footer, maybe a pre-poured deck footing?
    Would I sink a 4x4 and then anchor it in concrete, or make a concrete footer and connect a post to it with some Simpson strong-tie thing embedded in the concrete?

    I would consider paying a contractor HOWEVER, we just spent an obscene amount of money adding an "ensuite" bathroom to the kids room. Not because they need an ensuite, but because 4 (potty trained!) people can't live in a house with one bathroom, and the only logical place we could add a bathroom was hanging off the kids room!

    I'm amazed Sandy even SUGGESTED that I "get a proper tank". I think all my DIY stuff hanging off the 58g is bugging her to the point that she somehow thinks that a "professional tank" would be better. Well, a 180 has a bigger cabinet so it will will hide more stuff.

  5. patchin

    patchin Facilities / Event Coordinator

    What a cool wife!
  6. iani

    iani Guest

    This is what I did for my tank.

    My friend Jimmy (building inspector) said ideally you should dig into the ground 1' for the footing. But the ground under my house was rock solid and its really only holding about 1 thousand pounds per footing. He thought it would be overkill already as is.
  7. Vince, glad to hear you made it through a day of 3 dimensional puzzle-piecing! Hope everything came together OK and the girls are enjoying their new beds. Good to know the furniture continues to be put to great use.

  8. jellygeee

    jellygeee Guest

    +1 for reinforcing the floors since it will give you a peace of mind in the long run. You can check in Ian's link for the foundation support that he is using.
  9. rygh

    rygh Supporting Member

    > rygh: Thanks for the tip, I will do that. Would you put the 4x6 "on edge" so that the weight is on the edge, or the face? I'm guessing edge.
    On edge.

    > There is "rat proofing" under the crawlspace, which is also unfortunately not flat (it sort of follows the contour of the ground rather than having been
    > leveled. However, It won't be too hard to break it up and sink a concrete footer or two. Instead of pouring a footer, maybe a pre-poured deck footing?
    > Would I sink a 4x4 and then anchor it in concrete, or make a concrete footer and connect a post to it with some Simpson strong-tie
    > thing embedded in the concrete?
    It really depends on the type of dirt under your house.
    If it is soft/sandy, you need a wide concrete footing.
    If there is a thin layer of soft soil, you want to go deeper to get through it.
    If it is hard clay, a couple of concrete pavers would do.
    Fortunately, that dirt should stay nice and dry, so will not move around or get muddy and change.

    Given your posts, and assuming "fairly normal dirt", my suggestion:
    Use 3 or so precast deck footings.
    Dig down about 1/2 length of the footing, wet down the ground under the footing, place the footing in the dirt,
    pound on it a bit, fill dirt in around the footing a bit(not above grade though).
    Then wait a week or more to let the dirt fully dry out.
    The reason: This gives the footing a solid connection to the grade, and even provides a bit of uplift resistance.
    Using 3, that is only 800 points or so each. Not much.
    Just get the precast footers with the little piece of wood on top, or with brackets already embedded.
    You place the 4x4 post on top of that, and screw them together.
    Make sure all wood is treated, and still keep it well up from the dirt.
    The last thing you want is to do all this work, and end up adding a termite-path to your house.

    > I'm amazed Sandy even SUGGESTED that I "get a proper tank".
    I was a bit surprised by my wife as well.
    But don't underestimate how "into" it they might be, and how excited they get about something big.
    PS: Get her involved in some of the decisions.
  10. rygh

    rygh Supporting Member

    Yep, that looks great. Simple precast footings and everything.
    Jacks might be overkill, but is certainly better, and saves work in measuring posts so carefully.
  11. Vincerama2

    Vincerama2 Evil Overlord

    Hey, would Home Depot have the "screw jacks" (or whatever they are called) and footings? I'm going to look in the crawlspace tonight to check out the spot where it might go, maybe take a pic to post.

    I'll have to wire in some power to that spot too as that wall has no outlets (stupid 1939 build house!)

  12. CookieJar

    CookieJar Guest

    For wiring, I'd wire at least 2 circuits, I've had to add circuits 2 different times for my 180.
  13. Plumstr8

    Plumstr8 Guest

    Similar to what figerwrinkles said, you most likely have floor joist 16" on center, length unknown. There is a whole bunch of factors when reinforcing wood framing for large loads. For example 16" spacing is common, but there is also 12" spacing which is much better. Another very important factor is the distance between each end of your floor joist meaning where the ends rest on the foundation and or load beams etc. (also known as SPAN) This is where the "SAG" factor comes into play. If you have a 2x6 floor joist on 16" centers, with a span of around lets say 10' or 12' feet. The weakest area is in the center. The closer you place the tank to either end of the joist (load bearing portion on each end) the better the support will be.

    My suggestion is to fiqure out the dimensions I talked about above and then I can help you calculate the rest from there! :bigsmile:

    Its not a good idea to just start slapping wood and building things without first doing the math, overcourse over-kill works but it also cost time and money.

    Depending on the dimensions you have, it could be a simple as adding one joist next each of the existing ones that will be under the tank area.

    Let me know, and good luck.
  14. JAR

    JAR Supporting Member

    That or just slap a post and pier or two under the joist and cut the span in half or thirds.
    Many times in order to get another joist in next to the other you may run in to a pipe, some wires insulation, or existing blocking or nailing that make it a PITA.
    Are you in SF?
  15. Vincerama2

    Vincerama2 Evil Overlord

    I'm in San Mateo, I'll take some pics and measurements. There would be a lot of furniture juggling so I think once I pick up the tank, it'll sit in the garage for a bit while I do all the reinforcing work. I'll get together some pics/diagrams. Thanks for all the tips and help! I've been reading about preformed/prepoured footings (mostly when used with decks). I think I can do that, and cut down the span with a perpendicular joist.

    I was under the house (easy access, since we have a "basement" that has a door to the crawlspace) to take a quick peek, unfortunately, I also put 10 boxes of outgrown baby clothes in that spot too, so I couldn't get a great look at the proposed spot, I'll do that today and get some numbers together.

    Thanks guys! After I pick up the tank, I'll start a tank log, though all this prep work is part of the setup.

  16. Vincerama2

    Vincerama2 Evil Overlord

    Some more info

    OK, so the tank will sit perpendicular to joists, which is good I think. The joists sit about 4 inches on the concrete foundation at the wall. About 10 feet from the wall, there is a joist that runs perpendicular to the other joists (it holds them up I guess) that has posts running down to concrete footings.

    So the "span" is 10 feet, with 4" of joist sitting on the foundation at the wall.

    The room that will have the tank is 11 feet long, the 6 foot tank will sit near the wall. I'm guessing a reinforcing joist/posts only needs to cover the 6 feet that the tank sits over, with overlap of course! 4x6's come in 8 foot sections, then I guess I'll cover the tank length easily. (would an 8 foot support joist need 3 posts? where would I place them?)

    Oh, the floor joists appear to be 2x8 about 16 inches center to center.

    There are some pipes and wires in the way, but the one wire that might be in the way can probably be re-routed a bit.

    Would I sister the current joists, or simply add more joists?

    The joists are about 2.5 or 3 feet from the floor of the crawlspace, it varies because it's not level. SO the posts would be short-ish.

    I'll provide pics later, I took some, but they are dark and I need to offload them from the camera.


  17. Plumstr8

    Plumstr8 Guest

    No we can get some where! Since your going to placing the tank near the wall, most of your load will transfer to the foundation or load beam depending on which side of the room the tank is on?

    Having 2x8 floor joist and NOT 2x6 is very helpful, the 2x8 can handle more of a load. First thing I can tell you is, I would NOT install 4x6 beam under the joist for more support. Ill explain why, it does seem to be an easy route to "beef" things up and sometimes can be. But since you have an existing crawl, I think you said in an earlier post there is cement rat proofing. The cement "rat proofing" is only a thin NON structural cement coating poured on top of soil. If you where to place the post blocks on top of the rat proofing to hold up the newly instaled beam. Once you place an actual load on the floor above, there is a BIG possibilty that the post blocks will crack the rat proofing and no longer be holdingany of the wieght.

    Under normal construction practice, anytime to are going to place a load onto the ground or cement the material beneath must be either compacted (DIRT) or in the case of concrete, you would pour a larger cement footing under the center of the area where the post rest. Some will say that the LOAD you will be adding is not going to have that much of an effect. But I can tell you 100% that the ratproofing is going to crack or break, if its dirt and you dont have full compaction, the post will just settle further in the ground over time. This is why I think that idea is going to be more work for you in the long run.

    I would strongly suggest installing sistered 2x8 joist to your current framing as a fix. Make sure that you install the new 2x8 joist so that they rest on your foundation and the load beam the same as the existing ones. I have a very helpful tip for an eaiser installation as well: before you take the new joist in the crawl space, take a table saw or skil saw and slighty remove one corner of the joist lengthwise (end to end the long way)

    When you install the new joist your going to have to "ROLL" them into place, during this process the joist get caught or hung up on the bottom side when you try to stand them up straight. If you take one corner off as I stated above, it wont be so hard to turn! When you slide your joist in, put the corner of the joist you cut, down towards the crawl space and facing the existing joist you are sistering it with.

    Also remove any nails sticking out proir to your install, they can make you go nutz if you miss any, ONE can stop an entire joist from being able to turn upright!

    If there is any wiring or piping dont be affraid of putting some notchs in the new floor joist, just dont exceed 25% from either edge of the joist or you will be moving in the direction of cutting it in half which is not good:(

    If you have any more questions let me know!
  18. rygh

    rygh Supporting Member

    Sounds pretty strong already.
    Joists perpendicular to the wall is great.
    My thought is that you can simplify:
    1) Sister maybe 4 of the joists, from wall, out about 4'.
    2) Add an extra board under the joists at the foundation.
    Such that old joists + sisters have a VERY solid compression path down to foundation at the wall.
    At 10' versus 2', The load on the wall will be 80%, the load on the 10' out posts is only 20%,
    so if you just strengthen the tank/wall area, I cannot see it being an issue.
    And a whole lot simpler than posts/jacks/etc.
  19. Vincerama2

    Vincerama2 Evil Overlord

    OK, so it the tank is 6 feet long, then at 16 inches center to center, that means about 5 joists at most will be under the tank. Should I sister them all? With 10 foot 2x8s ? Odldly, I thought most sistering was done with engineered wood on both sides of the joist (3/4" plywood?). I will off course, use whatever you guys suggest. Do I sister all the way to out to the supporting beam 10' from the wall? Mike's response seems to indicate that, Mark's response says "4 feet out".

    Mike, incidentally with the post idea, I was going to cut through the rat-proofing, , pour down some concrete and then set the pre-formed foundation into that. If I can get away with just sistering, then that's much better. Thanks for the corner cutting idea, I think I understand what you mean.

    Mark, how can I add an extra board under the joists at the foundation if the joists are already resting on the foundation. From what I can see the mudsill is embedded into the foundation and the joists sit on top of that AND the foundation. Were you suggesting, if the mud sill sat pround of the foundation, to add a board next to the mudsill, wedged between joist and foundation where the foundation was not in contact with the joist? I'm a bit confused.

    And guys, thanks for your help, I REALLY appreciate it!

  20. Plumstr8

    Plumstr8 Guest

    I would only sister the joist under the tank and run them the full length. (2x8x10')

    If you only run them out 4' as mark suggested, you would still need something for the end of the sister joist to rest on. Otherwise they wouldnt help anything, just extra wood hanging in space pretty much. It kinnda double work, having to use both ideas.

    Also, your post idea would work fine if you removed the ratproofing and poured the extra concrete. Thats exactly how I would do it :) if your going that route.


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