dampness on interior of concrete


  #1  
Old 04-23-16, 09:05 AM
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dampness on interior of concrete

Am redoing an entrance room and noticed damp on the inside of the grade behind where the styrofoam is.
Is there anything I can do to waterproof this or is it necessary? There are no puddles of water but the dampness could harbor mold.
The room is below some concrete steps and a balcony. So, the dampness is actually both at the above ane below the levels of soil outside. Didn't think concrete could get risiing damp so not sure why the upper levels of concrete are damp.
You can see by the colour of the concrete where it's dry and wet.
Angle in the 1st photo indoors matches the angle of the last photo (outdoors).













 

Last edited by qwertyjjj; 04-23-16 at 09:34 AM.
  #2  
Old 04-23-16, 03:58 PM
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welcome to living underground,,, conc's porous so it sucks wtr thru capillary action,,, wtr vapor also penetrates conc,,, coat exterior w/slm5000 or equal

high humidity in a bsmnt is also a cause
 
  #3  
Old 04-23-16, 08:04 PM
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Yeah, but the concrete above ground is also wet, you saying it sucks the water upwards?
Just strange that it`s wet on one side only. The back is also below ground.
Can`t coat outside as most of it is below ground.
Could coat the above ground part but that`s also painted.
 
  #4  
Old 04-24-16, 04:16 AM
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Waterproofing is always best addressed on the exterior side. Unfortunately that often means excavating the foundation in order to do so. Sometimes diverting downspouts further from the house is enough. Basically anything that will channel the rain water away from the house.
 
  #5  
Old 04-24-16, 05:15 AM
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Already did that last summer with the downspouts. This could also be run off from the balcony from snow melt but still strange it is on one side only.
So, this is normal for concrete?

Also, what R grade styrofoam should be put on the inside of walls?
Anything I can coat the inside with?
Any membrane I can put near the soil on the outside? Those rocks will be impossible to move without a digger / JCB.
 
  #6  
Old 04-24-16, 05:28 AM
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Unsealed masonry is great at absorbing moisture You could apply Drylok to the interior side but that can trap moisture in masonry which will eventually find another way out. Masonry saturated with moisture has a shorter life span. Excavating the exterior is a lot of work but the best way to waterproof the wall. Obviously mechanical excavation is easier than manual.

Someone else will have to address the foam insulation question.
 
  #7  
Old 04-25-16, 10:40 AM
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Before I too it apart, the concrete was against 1inch styrofoam, then drywall. Presumably the styrofoam would have stopped it drying out anyway as it was right up against the concrete?
No air flow?
Only other way it can dry is by the outside soil drying and then the moisture would move the other way...
 
  #8  
Old 04-25-16, 11:31 AM
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Water and moisture vapor can travel in excess of 100' vertically. Capillary action is how tall trees get their water to the upper reaches and why they rarely exceed 400'. I was being conservative with my 100' statement.

Basically you know the moisture is coming from the outside and as you can see it can wick vertically. Your choices are to seal it from the outside, which will be difficult as it can continue to wick in from below the footings, or manage it on the inside.

The pink rigid foam, unless it is coated with plastic, should allow a slow diffusion to the inside (emphasis on slow) and the drywall should allow continued drying to the inside. A couple of "if's". If the humidity level inside is low enough and if the paint used is not acting as a vapor barrier.

You said "The room is below some concrete steps and a balcony." Is this a closed off space or open to the basement where the moisture level is being controlled?

Bud
 
  #9  
Old 04-25-16, 06:41 PM
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Closed off - it's actually the front door and entry room to the rest of the house. Thinking about having the door to inside the house (not the front door) open in future, ie remove the door, which would help the humidity.
Is it better to seal it or let it breathe?
 
  #10  
Old 04-25-16, 07:52 PM
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Reducing the humidity in that entry room would help, but it just looks like you are dealing with a lot of moisture.

Put a dehumidifier in there and monitor the RH level and see if you can dry it out.

Now, since a lot of that wall is above grade on the outside you should be benefiting from some drying in that direction, unless the wall is gaining moisture from roof run-off or direct rain. What is covering the outside, the white surface I see?

Bud
 
  #11  
Old 04-26-16, 11:02 AM
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Think there is black paint or some kind of waterproofing below ground that I can just see.
Above that is white paint and just concrete underneath.
Funnily enough, the moisture dried out once I had removed the prink insulation.
 
  #12  
Old 04-26-16, 11:35 AM
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"Funnily enough, the moisture dried out once I had removed the prink insulation. "
That tells you the moisture is being trapped with no direction to dry. Even though the pink rigid has some permeability, that can only pass a small amount of moisture.The paint on the exterior of the concrete may be acting as a vapor retarder. Some paints are actually listed for use in place of a vapor barrier. The black paint you see below grade doesn't include under the wall, the footings, so moisture can also be coming up from there.

Still no firm recommendation.

What is going on up top? Is the top of that concrete wall exposed to moisture? Even though moisture can wick upwards it goes down much more easily.

When it rains, does run-off or direct rain hit that wall?

Bud
 
  #13  
Old 04-26-16, 12:49 PM
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It's some steps leading onto a concrete balcony.
There were leaks in the past from what I can see of the studs that we ripped out.
However, on the inside, the ceiling and back wall were dry.
The only wet wall was the outside one.
Rainwater and snow melt could potentially leak over the balcony edge, down the paint and onto the ground.
There is a small section of unpainted concrete on the outside but doubt it would be that.
The balcony on the top side has had cracks sealed with crack filler cement. There is also some leveling cement added from maybe 15 years ago when that leak originally happened but that was on the inside wall inside, which shows no moisture.
 
 

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