Bath Tub Wall Damage
Bathtub wall damage can be created by a variety of different things, but the main culprit is going to be water. Let's face it, people use water while taking showers and bathe in bathtubs. As long as the waters around, there will be a possibility that something will get wet and if that something is the bathroom wall, then this is what you could end up with.
The most common problem you're going to have with damaged bathroom walls
from moisture will be water leaking over the side of the bathtub or shower.
Now the most common cause of this will have something to do with the shower
or bathtub enclosure door or curtain.
Doors that are installed incorrectly or damaged and are having a difficult time keeping most of the water inside the bathtub or shower enclosure will need to be repaired or replaced. You can check these doors or shower curtain by opening and closing them to see if there are any gaps where moisture can escape while using the shower.
If you own the home, you could always get in the shower and check for water escaping while you're using the shower.
You might even realize that you're not the culprit. One time I was talking to a large man who said he had a difficult time washing his hair, because the shower head was too low. It took him a while, before he realized that repositioning himself, to wash the soap out of his hair, was actually causing water to spray onto the ceiling of the bathroom.
You could find yourself in similar circumstances. Someone in your home might not be closing or using the shower doors or curtains correctly. If this is the case, your problem could be easily solved.
The Problem Could Be Starting at the Bottom?
There's one more thing I would like to point out and it's not something
most of us are familiar with. That's the fact that water can actually work
its way up a wall, giving you the impression that the damage starts at the
top, but in reality could actually be starting from the bottom.
It's often referred to as water wicking up the wall and I've seen it go as high as 36 inches.
If I was to guess, the damage caused in the picture above is the direct result of moisture accumulating around the base of the wall. Water somehow gets out of the shower or bathtub, then pools up around the base board, giving it plenty of time to soak into the drywall and possibly house framing.
Can I Paint This Type of Bathroom Wall Damage?
Realistically you can, but you're not going to solve the problem. Make sure you find out what is causing the problem and creating the damage, before painting. If you simply paint over something like this, you're just going to be covering up the problem.