Sanding Walls - Exposed Powdered Surface?

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Breezer23

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I recently purchased a condo that was painted sea foam green by the previous owners. Can't stand it! The place was built in 1978 so I expected a few issues but not a huge section of wall! So I started sanding with an Orbital sander. Everything went fine though, on one wall, I noticed the wall texture was different from the surrounding area and there were small pores in the paint surface. After wiping this section down with water that paint started blistering. Moisture issue. Not a big deal I had this issue when I painted the bathrooms a few months earlier - expected it.

I put the sander on it again. Paint came flinging off but not to expose sheetrock but a fine off white surface that turned to powder when I put the sander to it. What is this? Mud? What is the proper way to fix it? My fear is the majority of the back wall is like this! I am starting to miss the sea foam green!

I've attached a few photos and any help would be appreciated. I want to make sure I do this right so the next owners don't have to go through this too. Also, ignore the little white section. In addition, you'll notice it's framed between two sections of sheetrock. There is also a small section that is red. Really bizarre!

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It’s joint compound, Why are you sanding at all? I would have just wiped it down and painted it and if I wanted to give it a little tooth for the new paint maybe went over it lightly with a sanding pad just to scuff it up.

Oh and welcome to the forum. :welcome:
 
It’s joint compound, Why are you sanding at all? I would have just wiped it down and painted it and if I wanted to give it a little tooth for the new paint maybe went over it lightly with a sanding pad just to scuff it up.

Oh and welcome to the forum. :welcome:

I have just been going over it lightly with the Orbital sander. Used this to speed up the process a bit and smooth out all the imperfections from years of half arsed work. I was also hoping it would help locate the moisture problem before applying the new coat of paint, which it has.

The sanding has been really great so far except this section. Wonder why there is joint compound here....?

And thank you! Lot of great info on this forum!
 
The joint compound is there most likely because there is an ongoing moisture problem and it got bad enough someone put a patch on with a bunch of different products to mask the problem. What is above and behind that wall?
 
Knowing the way the previous owners did things, I'm sure they did the quickest and cheapest thing to "fix" whatever the problem is/was.

This section of the wall is whether backing an exterior wall or its shared with my neighbors living room. My condo juts out about ten feet from theirs and this is right about where their front door would be if that makes any sense. Above the wall would be my bedroom.

You're making my wonder, if this happens to be a section that is backing the facade of the house (cheap vinyl siding) if there might be an issue there. Maybe something exposing this area to the environment via a small crack of something?
 
It could be something like that. Maybe post a photo of the outside at that area. Worst case would be taking down the one sheet of drywall or maybe two and seeing what’s going on behind it. It might be easier in the long run than repairing the stuff that’s up there.
 
I'm curious about if they just patched the wall after pulling wires for that receptacle. I notice it's horizontal, are all of them in your unit like that?
 
Small patch at the top, small patch at the bottom: they could have been pulling wires for that receptacle. But that doesn't explain the big patch. I would guess there's a moisture issue with the exterior siding or flashing. That would make it a HOA problem, I would think. Problem is, you may have to open up the inside wall to prove it. That may actually be worth it, since there may be damage from a continued water problem.
 
Small patch at the top, small patch at the bottom: they could have been pulling wires for that receptacle. But that doesn't explain the big patch. I would guess there's a moisture issue with the exterior siding or flashing. That would make it a HOA problem, I would think. Problem is, you may have to open up the inside wall to prove it. That may actually be worth it, since there may be damage from a continued water problem.

The two patches are from me. I patched over the phone line out since we live in 2015. The patch at the top is a patch over the joint compound issue before I got overly ambitious with the sander lol.

I looked outside, this is definitely back to an exterior wall but I don't really notice anything.

I put a ton of water on the painted part next to the mess to see if the paint will blister. If it doesn't I may just mud that section and move on. I don't have the funds to bring in a professional
 
Replacing a section of drywall is easier than most people think. I don't know your skill level, but if you have a few basic tools, there are guys here who will give you the step-by-step.
 

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