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Can a slab-on-grade be salvaged after a burn-out?

Discussion in 'Residential Foundation Codes' started by Jobsaver, Mar 14, 2011.

  1. GHRoberts

    GHRoberts Silver Member

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    I asked because I think you are asking for something completely outrageous. (I like the contradiction of you wanting a core sample and peach saying a core sample will destroy the vapor barrier. I accept different opinions, but I would be more comfortable if those asking for "proof" had a good engineering background.)
     
  2. fatboy

    fatboy Administrator

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    "I accept different opinions, but I would be more comfortable if those asking for "proof" had a good engineering background.)"

    Hence, we ask for an "engineers" opinion, because us common folk don't have an "engineering background" and as we are repeatedly told, can not "practice" engineering..........
     
  3. Jobsaver

    Jobsaver Registered User

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    Taking core samples, or poking other holes, through the vapor barrier will affect the integrity of the vapor barrier. However, the integrity of the vapor barrier can be largely restored through the core sample opening left in the slab, before patching the concrete. Work an oversized piece of 6 mil into the opening under the edges of the hole.
     
  4. fatboy

    fatboy Administrator

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    And to that question.........living and working in the great American desert, we don't even do the vapor barrier around here......so non-issue. But yes, I think you could figure out a way to reseal the barrier, where it is required.
     
  5. peach

    peach Registered User

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    fat... you have no vapor issues in CO?

    To skew the topic a little.. I just sat thru a meeting with Roux associates.. they do mostly environmental stuff... the biggest new thing in their field is contaminated vapors from contaminated soil ... just a thought.
     
  6. fatboy

    fatboy Administrator

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    It's drier than .......well, we'll just say it's very dry, soil and air.
     
  7. peach

    peach Registered User

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    Yeah.. been there... BUT this new thing is vapors from contaminated soil (which can travel a long way)... old UST for example.. all the liquid needs to do is find a sanitary or storm or water line to follow and it's there... I think we'll be reconsidering slab vapor barriers everywhere.. all vapors need it differential pressure to get into the building.

    Hi Fat, btw...
     
  8. fatboy

    fatboy Administrator

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    Hey back peachy........Yes, we are in the middle of finding out about travelling vapors, have a odor problem popping up in some basements in a subdivision, that we can't figure out how its getting there. How far do you think vapor can travel underground? Very frustrating, not the city's problem per se, but in the interest of customer service we are trying to figure it out.
     
  9. Pitt Boss

    Pitt Boss Registered User

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    Hi Everyone,

    I am new to site and greatly appreciate your advice on my question in advance !

    There is a fire damage house in Virginia that I am starting to rebuild.

    This is new to me, what is the safest approach to make sure the slab is ok to rebuild on?

    Thanks for you help
     
  10. e hilton

    e hilton Bronze Member

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    Depending on how bad the fire was, it might not be acceptable. I would recommend you engage an engineer to examine the slab and issue a report.
     
    Msradell likes this.
  11. Pitt Boss

    Pitt Boss Registered User

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    Thank you, a structure engineer would be able to perform inspection ?
     
  12. e hilton

    e hilton Bronze Member

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    Yes. Call and talk with them, most will tell you over the phone if they can do the job or will refer you to someone who can.
     
  13. ICE

    ICE Moderator

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    I have witnessed many concrete slabs reused after a fire. There is no easy way to determine if the slab has been damaged unless there is spalling or color changes. If the use was something that would stress the concrete it might be an issue but a house.......not so much. Tap it with a hammer. I used to find bad spots in pool plaster by dragging a hammer head across the plaster....It was easy to find bad spots just by the sound.
     
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  14. e hilton

    e hilton Bronze Member

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    Dragging a chain across a concrete slab is a recognized method of finding hollow areas.
     
    ICE likes this.
  15. ADAguy

    ADAguy Registered User

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    Depends on how "green" the slab is. Too green and they may blow up. I have seen it happen.
     
  16. jeffc

    jeffc Bronze Member

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    I've required the use of a Schmidt Hammer for nondestructive concrete strength tests in the past. Just make sure that the hammer has been calibrated recently.
     
    ICE likes this.

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