Reinforcing floor for large tank?

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

  1. rygh

    rygh Supporting Member

    Might be some miscomunication there.
    It acts as a lever arm.
    The tank is next to the wall, so that is where most of the load is, not at the posts 10' away.
    Like a lever, you need to beef it up near the fulcrum. The fulcrum being at the wall where it goes to the foundation.
    So yes, you need to make sure you SOLIDLY support the sister joists down to the foundation, at the wall.
    But you only really need to do that end, not the other end. And as you get farther from tank, you have less load,
    hence being able to cheat a bit, and not go the whole length.
    And not going the whole length simplifies installation hugely.
  2. JAR

    JAR Supporting Member

    Plywood would work really well actually. It would be a pain to do it that way though.
    You would want a 10 foot piece and then you would need to rip it down in to 7 1/2 inch to use it to glue and nail the crap out of it to laminate it to the joists.
    If you have no wires and or pipes in the way I would just sister the five joists with 10' 2x8's.
    If you have pipes and wires then the post and pier method might be the way to go.
  3. Vincerama2

    Vincerama2 Evil Overlord

    OK, cool, so it looks like sistering the joists is the way to go. One other dumb question...

    Connecting the sisters. Should I use bolts & washers? 3/8" bolts? Does it matter where I bolt them? Should I use construction glue between them? Should I pre-drill the sister so I don't have to drill through both? Should I use deck screws as well?

  4. sfsuphysics

    sfsuphysics Supporting Member

    Mike Holmes suggests to glue it and screw it :D

    Especially if you're doing plywood.
  5. JAR

    JAR Supporting Member

    If the sisters are full length 2x8 resting on the sill plate and the beam then bolting is not critical. You just need about 1 1/2 inches if bearing on each side.
    Nailing them is fine. I would put three 16d nails in rows every 16 inches. Gluing is a bonus. You can use liquid nails construction adhesive in a calk tube. That would be BOMB PROOF! (small flame-less bombs) As a contractor I implement this kind of retrofit all the time. If you have and questions I would be happy to talk to you about it. Unfortunately I don't work that far south but the job is easy especially if you have access to a compressor and a palm nailer. Doing it with a hammer is a PITA ans a nail gun would work for most of the nails but the top row you might need the palm nailer. The most time consuming part of the job is buying the lumber and setting up.
  6. Plumstr8

    Plumstr8 Guest

    +1 Glue & 16d Nails
  7. Vincerama2

    Vincerama2 Evil Overlord

    Palm nailer on the way from Amazon ;)

  8. JAR

    JAR Supporting Member

    Nice! Now you will need some ear plugs and eye protection. :)
  9. sfsuphysics

    sfsuphysics Supporting Member

    Got a link to the one you got? That has been on my man-cave wishlist for a long time, having don't the bongo drum hammer bit between beams before, never new one existed until my uncle showed me this neat one. However haven't been able to find one at any of the big-box stores
  10. JAR

    JAR Supporting Member

    This mini palm nailer is the bomb!
    Technical Details

    Shoots up to a 16d nail

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    Lightweight at only 1 lb

    70 Percent lighter and smaller than similar palm-sized air nailers
    Magnetic nose

    Product Description

    With all the functionality of a full-sized palm nailer at one-third the size and weight, the Grip-Rite GRTMP16 Mini Palm Nailer fits into tight spaces where a full-sized palm nailer can't. It drives up to a 3-1/2-inch 16d nail without creating hammer marks, and it features a magnetic nose to hold the nail in place, so you get accurate placement every time.

    ‚óŹ Strength and Durability in a Lightweight Package
    The compact Grip-Rite Mini Palm Nailer is designed to handle framing, hurricane straps, fencing, decking, and other nailing jobs in tight areas. Because it weighs just one pound, the tool is comfortable to operate for long periods without fatigue. Its compact size also makes it easy to store.

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    A magnetic nail holder keeps each safely in place during positioning to free up one of your hands. One you've set the nail, the Mini Palm Nailer accurately delivers multiple hammer blows until the nail is fully driven.

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    Included with the Grip-Rite Mini Palm Nailer is everything you need for immediate operation and maintenance, including a metric hex wrench to tighten screws, air tool oil for proper lubrication of O-rings and internal parts, and a male air plug.
  11. rygh

    rygh Supporting Member

    To each their own. I have not used nails in any significant way for many years.
    Square drive screws + cordless impact driver rocks!

    BTW: Beware of creating a squeaky floor.
    Those sister joists will not be attached to the floor, only to the original joists,
    so think a bit on how things move. Should not be a huge problem,
    but a good reason to use a lot of construction adhesive and nails.
  12. sfsuphysics

    sfsuphysics Supporting Member

    Thanks Jon, that looks like it might be a nice early birthday present for me ... (around 5 months early but who's counting!)
  13. JAR

    JAR Supporting Member

    I would love to see you frame a house with screws. :D
    Clearly you are not doing this kind of work on a daily basis like I am.
    If there is the slightest gap between the boards screws will not easily squeeze the board together to the next unless you pre-drill each one. Screws work great with most plywood and some decking materials but even with impact it is expensive, unconventional and not the way to do it. If he nails it off like I said to do he will use about 25 nails per board. If a 16d nail can hold about 100lbs this should hold the sister in place quite firmly. Once the glue dries that will be one bad a$$ upgrade.
  14. Vincerama2

    Vincerama2 Evil Overlord

    I picked up the Bostich PN100 kit

    I had considered the smaller palm nailers, but I had no experience to go on except what I read on Amazon reviews. This is almost twice the price of the mini at $67. It's the "kit" so it has a box (which is semi-important to me since I'm disorganized) with a few different heads (I won't really need that I think) and a "glove". HD sells a Rigid palm nailer for $70 and didn't have the "kit" stuff so I just bought this one. I was worried that the mini-palm nailers wouldn't handle the 16d nails.

  15. rygh

    rygh Supporting Member

    Yes, I have to admit, my screwing is strictly amateur. ;)

    I do agree with you that nails are great. And if glued, hardly matters anyway.
    But screws really have improved recently, and not just square heads.

    Regarding nail-gun driving of screws, check this out:
    Not just collated. They even have special angled threads, to fire in easy, but grab like screws.

    Regarding this common problem:
    There are a few brands that have fixed this. The threads are cut only on the end, so only bite into the lower board, and do clamp.
    For this application of 2x8 to 2x8:
  16. Vincerama2

    Vincerama2 Evil Overlord

    Argh! I took a look again in the crawlspace and noticed TWO PROBLEMS

    1) about 3 feet from the foundation there is a large cable that runs through the existing joists. It's either the cable from the main electrical panel to the subpanel in the garage OR it's the actual cable from the street to the main panel. Either way, I'm not going to disconnect it to run through a hole in the sister.

    2) The support beam at 10 feet has wood placed perpendicular to the joists (What do you call those? Blocks or something?) and those pieces are toe nailed into the joists. I don't know if they are spacers or something to keep the joists aligned, but if I want the sisters to sit more fully on the beam, I'll have to remove them, cut them (or use new pieces) and replace them. I'd replace them just because I figured that they were put there for a reason!

    Possible solutions

    1) I don't think I can get around notching the sister down to the hole, unfortunately the hole is pretty much in the center of the joist. Center meaning that it's halfway "up" the joist. If I drill a hole in the sister and then cut a channel form the top then the bottom of the sister will be intact (that's the portion in tension), I could then glue the removed wood back into the sister after it's been installed. Glue would fill the saw kerf of the cut I think. I could then use some 3/4" plywood to patch over the cut, extending about 2 feet out to either side. I suppose a rectangular piece 4' x 4" above the hole OR a full 4' x 8" piece that is notched on the bottom up to the hole (like a 'u' on the sister and an 'n' on the plywood) OR I could slap a 4 foot piece of 2x4 as a third sister above the notch OR a 4 foor notched 2x8 piece that is notched on the bottom. Do I even need to bother with any of this? Can I just use the notched sister and glue back in the removed notch, since the top of the joist would be in compression?

    2) I guess I'll have to pull the toe nails (Ha ha! Ouch! Ve haff vays of making you talk!) and smack the spacers out. Or drill a hole in them, and use the sawzall, being careful not to nick the beam. I just was wondering if the spacers are actually spacers, or just stuck there for the fun of it?

    Thanks! I'm mostly interested in what to do about the cable hole.

    I went to see the tank yesterday and it's big and heavy. In anticipation, I build a "transport cart" that should accomodate a 6 foot tank. I put casters on it rated to 500 pounds, but they are 2 inch casters, I think I'll go pick up some beefer, easier rolling ones. Mostly I built it because I'm sure that my wife won't be able to help me move the tank much and it will make it easier to move the tank from mini-van to cart (I built it at the same height of the mini-van deck, so minimal lifting would be needed. My friends and I are old and have old backs ;) The cart should also allow me to move it around in the garage as needed while I do all this structural stuff.

    Luckily, I have a mostly full, amateur wood shop which will soon also have a palm nailer ;)

    Again, thanks for all the great advice you've given me guys!

  17. Vincerama2

    Vincerama2 Evil Overlord

    rygh, I looked at the same screws! I bought some pocket hole screws from McFeely's and they send me a catalog all the time. Gotta love $1 shipping! With wood screws, I always predrill, If you don't use those McFeely screws, you have to oversize the pilot hole in the top piece, that gets rid of any jacking from the screws... but there is no way I'm going to do that on joists! For most other wood projects, I agree 100% that properly piloted wood screws can't be beat. My "tank transport cart" is made mostly with deck screws. Oh, and I have a 24v cordless Makita impact driver, it is completely awseome EXCEPT that it weighs a ton. I think they discontinued it and there are much better/cheaper impact drivers out there. For anyone who doesn't have one, consider getting one! I wonder why there are no corded version?!

  18. rygh

    rygh Supporting Member

    Possible alternative for cable/hole problem:
    Use two 2x4's as sisters, instead of one 2x8. One above cable, one below.
    Although it may not fit, or might be really hard to get the top on in.

    Cutting the notch and gluing in the old piece is not so bad from an engineering standpoint.
    The bottom of the board is in tension, and that is still intact.
    The top of the board is in compression, and a glue joint is fine for that.
  19. rygh

    rygh Supporting Member

  20. rygh

    rygh Supporting Member

    Of course, there is a guaranteed problem with the cut:
    There WILL be a big knot, right in the worst place.

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