Drying concrete

Discussion in 'Water, Fire, & Smoke Damage' started by Kevin B, Mar 25, 2017.

  1. Kevin B
    Kevin B

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    I have a very unique situation in an 9,000SF home. It has been exposed to severe sub surface mositure. Sump pumps have kept it managable, but there is water under the concrete. The river is overflowing its banks within a few hundred yards of the home and the water is actually at slab level or above(surveyor checked). What has saved them from major damage is the incredible drain system the home has, but the water needs to recede.

    We drilled a test hole(water came up) in the slab, and we taped plastic to the floor in places and moisture trapped under it in By the end of the day. We have currently dried the walls and removed all floor coverings except travertine. All contents are removed.

    What kind of conditions do I need to create to dry this efficiently? Approximately 3600 SF
    Of floor. I have my own plan to run with but wanted to hear some ideas.
  2. clean image
    clean image

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    From what it sounds your fighting a battle that can not be won, only controlled.

    Sounds like building engineering issues.

    The level of river 100 yards away may be irrevalent to what pressures the house sits on.

    We service a large commercial job, 100 yards behind it is a like that sits atleast 40 foot BELOW the slab level, yet when they leave mats on the honed granite, there is puddles of water underneath from moisture coming thru slab.

    I am no expert, however I know if you don't work with nature, nature will always win.
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  3. Desk Jockey
    Desk Jockey

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    Carl is right that is a no win situation until the water table level recedes.

    As mitigation and only if everyone was in agreement you could cover the area with poly sheeting and use a couple of LGR's and very low air movement to create a smaller drying chamber.

    Its not actually drying the concrete, you are only keeping things in check until the situation improves. You could be looking at extended rental depending on the weather. Charge appropriately and make sure everyone buys into you plan and price to do it.

    The big box store sell calcium chloride test kits to prove when it dry (a relative term when it come to concrete).
  4. kmdineen
    kmdineen

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    I would use laminar air movers to blow away the boundary layer of humidity that is directly above the concrete and to reduce the vapor pressure of the air. I would also use LGR dehumidifiers to also reduce the vapor pressure of the air and to lower the dew point. Use an IR thermometer and keep the cement slab well above dew point. I would not cover the floor with plastic.

    Once the water table has dropped I would use heaters, such as the E.T.E.S., to heat the concrete with the air mover set on low. Use a FLIR camera to monitor and document the slab temperature. LGR dehumidifiers will also be necessary. Good luck, it sounds like easy money.
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  5. Kevin B
    Kevin B

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    I do understand it is an engineering issue. But this house has been here for 13 years and the river is usually a small stream. It is white water rapids currently and that is not normal. It has 10ft ceilings, so it seems appropriate to tent the floor, not cover it in plastic but actually tent it. This is one of a few houses and we have been preparing them for extended drying not to "dry" but to control condensation until the water table recedes away from the home.

    When we taped plastic to the floor it was just a 12"x12" squares to check for moisture. We are just trying to get them to approve our long term goals. Any suggestions on acheiving a dry standard since the entire basement was wet wall to wall? We plan on using Lignomat sleeves and rh meters to document our progress on the slab.

    Our initial plan is tenting with LGRs and small air flow due to 10' ceilings to make the space smaller to dry.
  6. Desk Jockey
    Desk Jockey

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    Ask if they have a neighbor or friend realitively close and use their basement for the dry standard.
  7. Kevin B
    Kevin B

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    Probably cant use the garage because of density?
  8. Desk Jockey
    Desk Jockey

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    I don't know. You could always ask a concrete guy or a builder in your area if that pad is is poured a different density.
  9. Onfire_02_01
    Onfire_02_01

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    In my opinion;
    At best you are fighting a no win battle right now.
    Is there a way to add additional drainage between the river and house so that you can pump the drained water away from the house before it gets to the house? I am thinking of an external sump pump so the internal one is more efficient/ has less work to remove the water that is trying to come in.
    I would worry about your tenting of the area, it sounds like a great idea but how about the rest of the basement walls that are touching dirt, they may not be water in the dirt but you can bet the dirt will be extra moist at this point. I would suggest leaving the room open and constantly run several dehu's and a couple of fans to break that boundary layer.
    A dry standard is going to be hard to find. A neighbors house may be useful but remember that moisture is always migrating through concrete that touches dirt. {my basement concrete becomes visibly wet every spring and only drys out in the winter dispite having a Dehu running 24/7 all summer long}
    Take my opinion for what it is worth I haven't run into a situation quite like this before.
  10. Kevin B
    Kevin B

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    The house has a pretty significant drainage system out front. Large collection areas with pumps. It is honestly what has prevented major catastrophe of the river coming inside directly. They also put up several retaining walls of sandbags and 500lb ecology blocks.

    Right now, the survey stakes are about 3" below slab as the river is slowly receding.

    We have spent 4 days drying all the walls and all that. The concern is just how wet the concrete is. It isnt a normal wetness that is for sure. Its saturated and reaches dew point quickly and then grains indoors spike and we would be right back to square 1
  11. Matt Wood
    Matt Wood

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    Insurance adjusters like to have a good relationship with the restoration business in the fact that everything is honest. I would put the decision in the adjuster's hands and give him 2 choices on what you could do:
    a. Do what @kmdineen suggests and work on attempting to dry it underneath or
    b. Since you've already got the walls dried and finished, pull almost all your air movers and dehus out and just keep a few in there for a longer period of time to keep it from getting too wet and let nature dry the ground over time. Summer is coming soon and the ground should dry quickly. As long as you keep the air dry above the concrete, it should dry just fine once the ground outside dries.

    This isn't a normal water damage loss job, so the 3-4 day period shouldn't apply. Just keep a good log of moisture readings so the adjuster has a good record of why you're going more than 4days with everything
  12. Kevin B
    Kevin B

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    No adjuster...
  13. Nate The Great
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    Your RH probes may be damaged with too much moisture present.. My pops uses the Wagner disposable and Tramex Re-useable probes for his concrete moisture testing.. On freshly poured slabs here even after 90 days old you can read 99%rh..

    That @kmdineen is a smart guy, as is @Desk Jockey also.. I enjoy reading there take on solutions to drying challenges.. They help me see a different way of problem solving..
  14. Matt Wood
    Matt Wood

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    I'm sorry, I misunderstood. Forgive me please, because I do that ALOT. If there's no Adjuster involved, then I would give the same suggestions to the owner of the property.

    You said you already had your own plan. What is it compared to our ideas?
  15. Kevin B
    Kevin B

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    No worries. Not having an adjuster actually is making it harder because an adjuster understands the issues we are facing.

    Right now, I have a thermal hygrometer taped to the floor in plastic. We will come back and see what the reading it gives us in a couple days. It was at 37 grains and 36rh when I sealed it up. We will also use the RH and GPP readings of the house to document our need for continued climate/humidry control.

    We want to show the homeowner that this moisture needs controlled as condensation will happen in colder spaces like wall cavities and under cabinets. Our plan is to control it out of the significant danger zone with normal temps around 70F, air movement and LGR dehumidification. We will take RH readings of the concrete each week and address things as we go. Once things dry outside we will set them up with some dehumidifiers from drieaz that will help them control the moisture for the long haul. Units made for crawl spaces. We may also request a third party ASTM test of the concrete to get them back to normal. It might be a year before they can put certain floor coverings back in.
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  16. tres davis
    tres davis

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    I laid in the weeds as everyone was chiming in. All good info.

    It seems like you have a really good grasp on the problem and solution.

    My only 2 cents for getting paid for your time....

    Structure it as monitoring/inspection/supervisor and not equipment rental.

    If you give them a ton of info about your process then they might be inclined to just use your scope/buy equipment and do it on their own
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  17. Desk Jockey
    Desk Jockey

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    That might be a unique approach.

    Sell them the equipment, charge primo to monitor and buy it back from them for pennies on the dollar.

    No matter how you decide to bill this make sure they know where this is headed before you get to the end. I would also collect monthly for progress so you don't get strung out too far without payment.
  18. Kevin B
    Kevin B

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    Thanks everyone for responding. These unique and challenging ones, especially self pay are definitely not for the faint of heart!

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