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Footing Cure Time?

Discussion in 'Residential Foundation Codes' started by fehujber, Feb 7, 2012.

  1. fehujber

    fehujber Guest

    Hi new to the board but BCO for several years, way back when, during my first season, my mentor had me reject a footing as the contractor had started laying block within a 72 hour window after pouring. At the time he rattled off an ACI section and the contractor complied and removed the offending foundation. I have operated unopposed within this premis ever since then and without having to officially support this in black and white .......until now. recently here in PA I had a CONtractor, begin drilling and inserting rods and commence block laying roughly 20 hours after pouring the footings (No it was not High and Early). When I found this I issued a verbal NOV to the owner, who has since contested the NOV. Now comes the problem I have researched the 2009 IRC and the ACI 332-08 and cannot lay my hands on a specific section requiring a specific period of time for various mixes to cure before commencement of further construction. Can anyone assist? Or do I have my foot in my mouth??:banghd
     
  2. Mule

    Mule Platinum Member

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    fehujber welcome to the board. I understand what you mean by enforcing a code that you can't find when someone call you out on it!

    Unfortunately I can't help you with your question. I just wanted to welcome you! Someone will be along to help you out shortly!

    Again welcome~
     
  3. codeworks

    codeworks Gold Member

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    i dont have it here, but try aci 318, 72 hours seems right. it needs to at least get past the point of "green", set up, harden edges, etc. i've worked for guys that strip the next day, but wait asnother before strating to set formwork
     
  4. fatboy

    fatboy Administrator

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    We see contractors around here placing footings one day, strip the next and form walls, place walls the next. Less than 72 hours from excavation to dampproofing.
     
  5. mtlogcabin

    mtlogcabin Registered User

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    It will depend on the season. Another jurisdiction adheres to the 72 hours. During the warm month we see 24 hrs then the form work goes up and the walls poured about 48 hours from footing pour. Cold weather requires blankets on the footing for 48 hours minimum.

    1905.11 Curing.

    The length of time, temperature and moisture conditions for curing of concrete shall be in accordance with ACI 318, Section 5.11.

    1905.12 Cold weather requirements.

    Concrete to be placed during freezing or near-freezing weather shall comply with the requirements of ACI 318, Section 5.12.

    1905.13 Hot weather requirements.

    Concrete to be placed during hot weather shall comply with the requirements of ACI 318, Section 5.13.
     
  6. mtlogcabin

    mtlogcabin Registered User

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    My understanding from many years ago.

    The 72 hours was the average time it took for concrete to reach 25% strength. However that is under normal weather conditions.
     
  7. Papio Bldg Dept

    Papio Bldg Dept Platinum Member

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    same here. sometimes the foundation guys are calling their inspections in before the footing.

    most of our footing write-ups come on cold-weather and rain pours.
     
  8. fatboy

    fatboy Administrator

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    Oh, and welcome to the forum fehujber!
     
  9. righter101

    righter101 Gold Member

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    ACI 5.11 Provides the following:

    "Concrete (other than high-early-strength) shall be maintained above 50 deg. F and in a moist condition for at least the first 7 days after placement, except when cured in accordance with 5.11.3.
     
    #9 righter101, Feb 7, 2012
    Last edited by a moderator: Feb 7, 2012
  10. brudgers

    brudgers Platinum Member

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    Concrete does not need to be fully cured before CMU walls can be erected.

    1000 lbs of loading per square foot is less than 8 psi - i.e. not even 00.5% of final strength for 3000psi concreted

    And of course, type III cement develops most of its strength within 24 hours - if early loading with full structural loads is critical.

    In other words, you have picked up the bad habit of making up code out of whole cloth.

    The best course would, of course, be to just enforce the code as written.
     
  11. Mark K

    Mark K Platinum Member

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    brudgers is on the right track. You can start building on the concrete as soon as you walk on it as long as you do not damage the concrete in any way that impacts its final performance.

    Note the special inspection requirement to verify curing in Table 1705.3 in the 2012 IBC.

    The code is focused on performance of the completed construction.
     
  12. mtlogcabin

    mtlogcabin Registered User

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    The problem is it is not written in the code as to when concrete has reached sufficient strength to continue with different phases of construction.

    The info you provide about type III cement developing most of its strength within 24 hours is not found in the codes.

    The 72 hour number was picked up somewhere in some class or rule of thumb for inspectors to use just like some may pick up on your 24 hours with no code section to back it up
     
  13. JBI

    JBI Registered User

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    fehujber - Welcome to the board. As evidenced above, opinions will vary. The answer you seek is indeed not written in the Code itself, but rather in the correct reference standard. ACI 318 is the concrete 'bible', and will contain prescriptive/empirical time frames. Design Professionals can justify reducing those times, as evidenced above albeit gruffly by Ben (aka brudgers). At 72 hours I believe concrete generally speaking achieves 75% of design strength, but could be mistaken.

    You made a call in the field, you were mistaken. Stuff happens. Admit your mistake, explain your reasoning, move past it. Just don't repeat the same mistake.

    Get your hands on a copy of ACI 318 and do your 'homework'. An edge-a-muh-cated Code Official is a CON-tractors' worst nightmare and a Contractors' best ally. I have more than once refused to do a wall inspection the day after the footings were cast. Usually a 4PM footing inspection that begins with 'Can you do a wall inspection first thing tomorrow morning?'. "No, I can't" "Why not?" "Because the concrete will be too green to support the forms..." (of course in my head it is a much different conversation). If they're in that big a hurry, get the DPR to document the design change (most plans say 'per ACI 318').
     
  14. brudgers

    brudgers Platinum Member

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    No. The problem is that when the code is silent on an issue about which a code official was completely ignorant, the code official made something up.

    He then taught another code official that that was the proper procedure.
     
  15. brudgers

    brudgers Platinum Member

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    It doesn't need 75% of it's design strength to support a typical masonry wall during construction - or even a quite unusual one.
     
  16. Rio

    Rio Silver Member

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    We've stripped forms many times the same day we've placed the concrete. We do this because the forms are much easier to strip, and also easier to clean. Once it starts kicking it's not going anywhere.
     
  17. fehujber

    fehujber Guest

    OK, first things first. Thanks for all the input, many cordial some gruff. To both please understand my aim is to do things right, by the code as written OR REFERENCED, that is why I asked the question here and did not just stomp my feet and hold my breath and shout "Cause I'm the building inspector and I say so".:inspctr I have and will continue to admit mistakes and even apologize to contractors and homeowners when I am wrong. On the other hand if the IRC references ACI 332, 318, 308 then I will use them as tools to clarify and support my position. I have 332 but neither 318 or 308 and was simply asking if anyone could offer me a quote from either.

    I only want to enforce supportable positions on code. :agree
     
  18. Darren Emery

    Darren Emery Registered User

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    No.

    The orginal code official (see post #1) made a call based upon his understanding of an ACI document that provided direction in an area where the code is silent.

    Then he taught another code official what he thought was proper procedure.
     
  19. brudgers

    brudgers Platinum Member

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    In so far as I recall, ACI 318 etc. are silent on the issue at hand because the necessary strength for further work is only a Potential design issue relative to a particular project, and under ordinary circumstances it is not an issue because concrete rapidly gains strength during hydration. What ACI does have is hot and cold weather placement requirements to insure that standard building schedules can be met in different types of weather.

    What ACI does have is curing requirements to insure that the concrete meets it's design strength after 28 days.

    Back when I worked in the precast industry, we used a lot of TYPE III cement so that large structural members poured late in the afternoon could be stripped from the forms early the next morning - i.e. the concrete had to bond sufficiently to the tensile steel to allow the piece to be lifted by crane and stored at it's bearing points within eight hours (4000psi @ 24 hours).

    In my opinion, if you don't actually know what is in ACI 318, you damn well shouldn't be pretending to enforce it. And regarding my gruffness, you've had ever since "way back when" to obtain a copy (less than $200) and read it.
     
  20. brudgers

    brudgers Platinum Member

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    Darren, building codes are not some oral tradition. It's a written one.

    And anyone who doesn't read the codes for theirself, has no business being in a position of responsibility.

    ACI 318 is $160.

    Forcing the public to tear out walls and wait a week before going vertical because someone cannot be bothered to read it, is inexcusable given the relative costs of construction.
     
    aleegull likes this.

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