#3 vs #4 rebar

Discussion in 'After Hours Lounge (Off Topic)' started by DannyL, Oct 20, 2004.

  1. DannyL

    DannyL Stunt Coordinator

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    i'm having some concrete decking put in. i asked the contractor to put in #4 rebar but he says that #3 should be fine. he says that it is harder to evenly pour over #4 because of the thickness. we plan on putting some heavy marble and concrete furniture, fountain, etc. i'm worried about cracking. will it make any difference? thanks.
     
  2. Glenn Overholt

    Glenn Overholt Producer

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    Well yeah, or there wouldn't be two different numbers. What does the contract call for?

    If it says 4 and he's skimping, oh, oh, take pictures before it's poured!

    Glenn
     
  3. Lee L

    Lee L Supporting Actor

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    The number on rebar is the size in eighths of an inch. number 3 = 3/8", Number 4 = 4/8 or 1/2". I'm not an engneer so I'm not sure if there will be a real difference in bearing capacity (off the top of my head it seems OK, but knowing the exact use and conditions would help) but I can tell you that the excuse about it being harder to pour over is absolute BS since you are only talking about a difference of 1/8".
     
  4. Glenn Overholt

    Glenn Overholt Producer

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    Yep, that is BS. Maybe, and I really don't know, the #4 is much, much harder to bend. But at any rate, if they use 3 take some pictures before it is poured, and if it cracks later, you'll have some evidence when you sue.

    Glenn
     
  5. Henry Gale

    Henry Gale Producer

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    I'm wondering if the guy has some #3 rebar left over from another job and wants to use it for that reason.
     
  6. John Alvarez

    John Alvarez Screenwriter

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    When you say decking do you mean suspended in air or is it a patio on grade?
     
  7. Adam.Heckman

    Adam.Heckman Second Unit

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    I'm at work right now. In a structural design firm (across the Charles river from Fenway! GO SOX!).

    Let me know the loading on the deck, slab thickness, and what type of metal decking you're using and I'll let you know.

    Not that I can tell you myself, I'm just a lowly drafter, but I can find out...
     
  8. DannyL

    DannyL Stunt Coordinator

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    thanks for all the replies. haven't checked my computer since yesterday. it going to be a back yard patio 6 inch slab. roughly a 20 foot dimater circle. we are thinking about a large 14-16 foot diameter gazebo with a tile roof or a very large fountain- 12 foot diameter. i know the fountain is greater than 1000 lbs.
     
  9. John Alvarez

    John Alvarez Screenwriter

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    I don't think you need rebar for that unless this is something that you want. I know here in Fl. all our patios are 4inch pour with no rebar. You'll want to make footers to support the gazebo. Make sure you check code in your area to determine what's required for size and load.
     
  10. DannyL

    DannyL Stunt Coordinator

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    i don't have any local codes requiring the rebar, but i just want to lessen the chance of having severe cracking in the concrete.
     
  11. Glenn Overholt

    Glenn Overholt Producer

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    John - think earthquakes.

    Glenn
     
  12. Greg_R

    Greg_R Screenwriter

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    I just finished a 9'x9'x4" pad for my hot tub and used #4 rebar which was major overkill. Keep in mind that the fountain's load will be distributed (a woman in high heels probably exerts more psi on the concrete). For the gazebo you may be required (by code) to pour footings... especially in CA.
     
  13. John Alvarez

    John Alvarez Screenwriter

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    I'm used to sink holes that swallow everything....[​IMG]
     
  14. Lee L

    Lee L Supporting Actor

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    I would not worry about the #3 rebar then. I would definitely thicken the slab to about 12" at the locations you might expect a future fountain or gazebo to bear on the slab and make sure rebar is in the bottom 1/3 of the pour in those areas. In central NC, for the rest of the slab, you would be more than fine using 6/6 10/10 wire mesh. (a 6"x6" grid of 10 guage wires). In LA with the seismic requirements, maybe rebar would be preferred but is still seems overkill for an unattached accessory structure on a slab.


    Also, you might be well advised to run some 1 inch conduit for electrical and maybe something larger for future water lines if you really wnat to do that fountain. Even if you just stub them out 12" from the edge of the slab and not use them for a year you will be happy one day if you ever do and it should cost you virtually nothing.
     
  15. DannyL

    DannyL Stunt Coordinator

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    thank you all for your help! [​IMG]
     
  16. Glenn Overholt

    Glenn Overholt Producer

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    John, I've seen quite a few news clips of sink holes on TV! See, if the whole thing is going to go, the rebar won't help!

    The quakes get just as picky as tornados or anything else like that, If it ripped down the center of this new project and split it, who knows where 1/2 of it may be sliding off to. If something is on the center where it split, that might slide off too. The house (just a few feet away) can get no damage at all until this slab slides into the bedroom. Ouch!

    I really don't know, though. As long as the local building codes are met, but I do want to know how this whole subject came up with you, Danny.

    Glenn
     

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