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Help with wall condensation problem

rooferman | Posted in General Discussion on December 19, 2007 02:13am
I need some advice.  Here is the problem:  The customer has condensation/ice build up at the top of their outside interior walls on the south side of their home.  The facts:  Home is two years old, well insullated, built by a quality contractor, one story ranch, gas forced air heat, fully vented soffit, ridge vent, located in Ohio, issue appears when 20 degrees or below outdoors. 
 
It seems to me the top of the wall is cold thus the condensation appears there.  More facts: Double top plate……………insullated walls (batts) insullated ceilings (blown in) soffits are clear and there are the foam vents stapled to the roof sheating at the soffits to allow for ventilation.
 
I need some ideas for good detective work.  Thermal image the exterior?  Test the wall temp inside at different wall heights?  Check humidity level in the house?  Help!!!
This is a tough one. What are the fixes?  Mike L.
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Replies

  1. User avater
    IMERC | Dec 19, 2007 02:21am | #1

    WTB there is an air gap at the top of the bays in that wall.... ie... no insulation...

    or the insulation was put in wet and the south sun heat ' cooling condesation cycle is showing..

     

    Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming

    WOW!!! What a Ride!
    Forget the primal scream, just ROAR!!!

    1. rooferman | Dec 19, 2007 04:17am | #2

      Maybe the wall cavities don't have insullation at the top......but why?  Did the insullation drop down due to bad fastening practices?  Did they run eight foot bats and forget the extra foot? (Nine foot ceiling height)  Searching for the answers can create a lot of repair work after!!  In a perfect world I would zero in on the problem in the least invasive manner.  Ideas anyone?  Mike L.

      1. Piffin | Dec 19, 2007 04:28am | #4

        "Did they run eight foot bats and forget the extra foot? (Nine foot ceiling height)"BINGO! 

         

        Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

  2. Piffin | Dec 19, 2007 04:25am | #3

    "at the top of their outside interior walls"

    Gotta ask - what is an outside inside wall

    ;)

    I am going to assume you mean the inside surface of the exterior walls

    Thermal imaging can confirm this, but my money is one this quality builder using a lousy insulation sub. There are voids in the FG batts in the way it is installed in that wall. Bet he was a short guy who forgot his step stool that day

     

     

    Welcome to the
    Taunton University of
    Knowledge FHB Campus at Breaktime.
     where ...
    Excellence is its own reward!

  3. DanH | Dec 19, 2007 05:08am | #5

    How high are the walls? If you have 9-foot ceilings some places and 8-foot here, eg, then there is a drop ceiling. Often there is a failure to properly block the stud bays above a drop ceiling, so cold air can get into the stud bays from above.

    Also check the humidity in the house and the air temp near the ceiling. High humidity combined with poor air mixing could result in a layer of cold air near the ceiling that causes condensation.

    If your view never changes you're following the wrong leader
  4. Grott | Dec 19, 2007 07:56pm | #6

    Check with the local utilities, so do thermal scans for a fraction of a specialized contractor.

    Part of the service the utility provides.

    Garett

    1. DanH | Dec 19, 2007 08:01pm | #7

      I've also seen ads for relatively cheap infrared thermometers, though don't have any at hand.
      If your view never changes you're following the wrong leader

  5. RedfordHenry | Dec 20, 2007 07:58am | #8

    What's the point of thermal imaging or measuring wall temperature?  You can already clearly see that the top of the walls are cold enough for vapor to condense and freeze.  If the interior wall surface temp is below the dewpoint there is an insulation problem (probably compounded by poor ventilation and excess vapor).  Drill a few holes in the stud cavities to confirm presence/condition of insulation.  Maybe there is fiberglass there but it's saturated.  The immediate fix (maybe) is to address is source of vapor.  Where are the bath/dryer vents exhausting?  Are there flex vents for bath/dryer in the unconditioned attic that are choked with condensation?  If you can remove the excess vapor, then the condensation problem should go away.  Long term fix will likely require doing some exploratory surgery to figure out what's going on inside the walls.  

    1. Grott | Dec 20, 2007 04:15pm | #11

      Thermal imaging may show other places that need attention. If your gona take the time to fix it...fix it right.Garett

      1. DanH | Dec 20, 2007 05:46pm | #12

        Yeah, thermal imaging may or may not help, but in the best case it'll point right at the problem.
        If your view never changes you're following the wrong leader

  6. User avater
    Jeff_Clarke | Dec 20, 2007 09:53am | #9

    Is it heated with line gas (piped natural gas) or propane?

    Jeff

    1. rooferman | Dec 20, 2007 06:18pm | #13

      The home is heated with propane.  Do you have an idea?  Mike L.

      1. User avater
        Jeff_Clarke | Dec 20, 2007 06:55pm | #14

        That's quite possibly a significant part of the problem.

        Propane combustion produces a much larger quantity of interior water vapor than natural gas combustion.  It's something like an equivalent weight in water to weight in propane burned.

        You might possibly want to review with a mechanical contractor to see if the furnace is being properly exhausted.   Also, the addition of an ERV (energy recovery ventilator) to bring in tempered outside air will also help to reduce interior moisture and resulting condensation.  Dehumidification may also help.   Did you check the wintertime interior RH?   If it's above 30% or so you probably have an issue there.

        Insulation (or lack thereof) may still be problematic but the combustion equipment is certainly part of the problem.

        Jeff

        Edited 12/20/2007 11:08 am ET by Jeff_Clarke

        1. User avater
          kurt99 | Dec 20, 2007 07:13pm | #16

          The combustion of propane will release less water vapor and more carbon dioxide than the combustion of natural gas (methane). This is irrelevant with properly vented furnaces and hot water tanks. All the combustion products go outside any ways. It could have an effect with cooking stoves and unvented space heaters or fireplace logs but it would only be worse if he had natural gas.

        2. DanH | Dec 20, 2007 08:02pm | #17

          Neither propane nor natural gas should produce ANY water vapor inside the house, so long as the furnace is in good working order.
          If your view never changes you're following the wrong leader

      2. User avater
        kurt99 | Dec 20, 2007 07:00pm | #15

        Don't overlook the obvious that they may have a humidifier set on "Rain Forest".

  7. User avater
    loucarabasi | Dec 20, 2007 12:47pm | #10

    Can you purchase that new ridged gizmo they sell at home depot ( the one with the camera on the end of the hose to see behind the wall.) Good excuse to buy it. I think they are cool. drill a little hole and snake the camera in, look at the problem.

    My 2 cents, Lou

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