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Someone put joint compound over the poured concrete basement wall and then painted over it. This seepage isn't water--it's a little sticky where it hasn't dried, and it appears in a few other spots in the basement.

I want to just paint over this but I was going to use a nicer latex and I'm concerned it'll bubble... but I don't even know how this paint hasn't been ruined. Any ideas on what it is, and how to not have a latex paint get ruined by it?

here is a picture of the weeping

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    Joint compound plus paint, add some water coming from behind you will probably get sticky. Very good chance you will need to start at outside to fix, if you want a long term fix.
    – crip659
    Sep 29, 2023 at 12:36
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    Yeah, solve the problem, don't cover it. Concrete foundations are rarely considered a finished interior surface.
    – isherwood
    Sep 29, 2023 at 12:45
  • Yeah I was originally going to put up a wall, insulation, and a vapor barrier but right now all I can do is polish this turd. I just don't want it to fall apart in a month of painting it, that's the main goal. Sep 29, 2023 at 12:56
  • With the plaster there, I'm not convinced a sealant paint would work even to the limited degree they to when applied directly to the foundation material ..
    – keshlam
    Sep 29, 2023 at 13:26
  • A pressure washer to strip the inappropriate stuff applied to the concrete in the past; then try the paint-on waterproofers if that's the level of what can be done now.
    – Ecnerwal
    Sep 29, 2023 at 13:35

3 Answers 3

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This seepage isn't water

I'd be surprised if it's not. Seriously, that's probably some level of water getting into the plaster. Concrete is porous and can let some level of water in. Even if it's not seeping in from the outside, the wall is in a cool, damp place where it can condense moisture in the air.

Someone put joint compound over the poured concrete basement wall and then painted over it.

To call this sloppy would be an insult to every DIY hack out there. This was plain negligence. Have you ever asked yourself "Why doesn't this happen to walls normally?". The answer is simple: vapor barriers. This is why you put faced insulation in walls. This is why you don't just bolt drywall to concrete (or be even lazier and just slap drywall mud on it and call it good).

The way to fix this is you need to air gap the wall. The normal procedure here is you frame the concrete wall with 2x4s like a normal wall (using pressure treated wood for the bottom plate that will be sitting on concrete), then add faced insulation, and finally drywall.

It's also a good idea to make sure nothing can seep in from outside. There's supposed to be a whole ecosystem of things your builder did to ensure water moves away from your foundation. The good news is the water seems to be seeping in from the top, not the bottom. That could just mean you have a minor drainage problem. Check to make sure no water can pond near your foundation, and that gutters can channel the water away.

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    Yeah, the old "check and correct the surface grading" approach might be most of what's needed here.
    – Ecnerwal
    Sep 29, 2023 at 13:34
  • Not knowing where or how old the OP's house is, many of the water-mitigation techniques in use today may not have been required or even available when the house was built, so let's not be too critical of the builder. He may have done it to the highest standards of the time... But yeah, don't put lipstick on the pig and expect it to look good or last.
    – FreeMan
    Sep 29, 2023 at 13:39
  • @FreeMan I'm harsher on whomever did this because it's purely lazy. At the bare minimum, drywall with a standoff would fare better here. Heck, there's even primers that make concrete directly paintable. Even some mineral-spirit-cleanup primer with a good semi-gloss paint would have fared better here. To me, this screams whomever did this had some standard interior paint and leftover mud and needed to use one or both up.
    – Machavity
    Sep 29, 2023 at 13:43
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    I was specifically referring to the "whole ecosystem of things ... to move water away from the foundation" in the last paragraph. I guess that little detail didn't make it into my previous comment. I agree that drywall mud & paint directly on a concrete wall is an insult to DIY hacks everywhere... ;)
    – FreeMan
    Sep 29, 2023 at 13:52
  • House is 25 years old, and there could be some water drainage issues previously since I had the gutters replaced two years ago and I need a gutter buried and dumping somewhere else since my front walk is dropping about 2mm a year. ---- can't do newline since I'm on a phone but yeah the handyman that redid this basement should be shot. Drywall joints humped, feathered 4 inches at most, cracks from the tape job sucking, buckling carpet because they couldn't stretch it properly... and it's a black ceiling with brown walls and brown carpet. I say polish a turd because it looks like a turd. Sep 29, 2023 at 14:09
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You haven't told us what the age of the house is or where you are located but here's the thing: if you have an old house and you are getting water through your walls, it's likely related to your (now defunct) drainage.

Back in the middle of the 20th century, a lot of homes were built in the US. At the time, they used porous ceramic drainage pipes. This is why people call plastic drainage pipes 'drain tile' to this day. I remember as a child digging in my (parent's) yard and finding these bits of ceramic. They were crushed 'drain-tile' pieces.

The standard design of such systems was to lay this porous 'drain-tile' around the foundation or a home. The idea was that if any water drained towards the foundation, it would seep into the system and be routed away. This was probably a fairly effective approach as long as the system drained to somewhere.

Here's where the problem comes in. Those bits of ceramic I was finding in the soil were from the drain tile but not the part next to the foundation. What I was finding was the remnants of the part of the system that was supposed to take the water away. The ground shifts. Tree roots crush clay pipes like twigs under a truck tire. What these homes are left with is a porous pipe wrapped around the foundation with nowhere to drain to or at least it doesn't drain well. And to top it off, a lot of these homes have downspouts that run into this weeping pipe up against the foundation.

The water has to go somewhere and that somewhere is your foundation. A lot of people will see water coming in and think, "I need to waterproof my basement from the inside." I personally think this is a dumb idea. The goop that is coming in is likely a mix of water from the outside and whatever chemicals have been applied to the walls.

What's the answer if you are in this situation? Call a landscape company that does drainage. They will reroute the water away from the foundation. It probably won't be cheap so get a few estimates and make sure they are legit. You might even want to dig up the clay tile around the foundation and get rid of it.

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Someone put joint compound over the poured concrete basement wall and then painted over it.

How long ago?

They skim-coated a concrete wall with joint compound?

This seepage isn't water--it's a little sticky where it hasn't dried, and it appears in a few other spots in the basement.

Joint compound uses glue as a binder. The seepage is likely a water/glue mixture.

If you're looking to just paint it and forget it then you'll need to use an oil or shellac-based primer to hide the stains first. Then you can use a nice latex color paint. If you don't prime then the stain will seep through the latex in a matter of hours. Regardless, assuming you don't fix the water infiltration issue then the stain will re-appear at some point.

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  • No clue how long ago, at least 5 years I imagine. Sep 29, 2023 at 14:05
  • @zudebluvstein Is the seepage pre-existing or new?
    – MonkeyZeus
    Sep 29, 2023 at 14:07
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    Preexisting, I've seen tiny amounts change over time in other spots, but this large bit was hidden behind a projector screen. Probably just moisture content being trapped behind there Sep 29, 2023 at 14:33
  • @zudebluvstein I see, paint does not fix moisture problems. If this is just a flipper home then you can paint it and hope it doesn't resurface before someone buys it.
    – MonkeyZeus
    Sep 29, 2023 at 17:03
  • This is why I always use setting-type joint compound when I skim coat foundation walls.
    – popham
    Sep 29, 2023 at 21:57

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