Old, soft drywall
I have a closet wall with some plumbing behind it. It is older, probably 25 years. I tried to put up a shelf and none of the anchors would hold any weight. I am concerned the the drywall has been wet or is wet and that is why it’s soft. Basically I know I should have it checked out and the plumbing checked as well but I just don’t have the money right now. My main concern at this point is mold and mold spores effecting indoor air quality. So the question is: can I use a sealant on the wall to prevent mold from coming through? Just as a temporary, cheap fix. If so will a lead paint sealant do the trick? What are your thoughts?
The first thing you can do is a simple visual check. Do you see evidence of water marks on the drywall? Do you see mold? You may need to use a flashlight to look into all the corners, especially down at the floor and up in the ceiling. Secondly, does the closet smell moldy? The best way to check for mold is by sight and by smell.
There are some paints that are designed to repel mold - I would advise against a lead paint sealant. Some commercial paint companies sell paints specifically marketed to prevent mold and mildew; a Google search will turn up several options available at local hardware and paint stores. Make sure not to leave these around children or pets; they do contain fungicide. Once dry on the wall, it is fine (unless you have a dog like mine, who enjoys chewing on walls!).
The issue I see with this is if you do have mold behind the wall, it can still thrive behind the drywall, and potentially spread.
Best case scenario, you did have a leak at one point, softening the drywall, but you did not have a mold issue. If that is the case, removing the drywall, checking the plumbing and replacing the drywall will be sufficient when you are able to get around to it. If, however, you suspect the plumbing is currently leaking, that is a more timely issue, as the water can certainly cause a mold problem, but could also cause more structural damage.
One other way you can check to see if moisture is a problem is to purchase a relative humidity meter- you can purchase these at most hardware stores. A simple one should be less than $15. Humidity in the home should be below 60%, ideally between 30-50%. Mold grows very well at humidity above 60%. I've included more information about mold from the Environmental Protection Agency - I hope this is helpful!
I have ordered a relative humidity meter. I am scared of what I will find.
The wall and floor were done very sloppily. The back lower corner is held together will expanding spay foam. There are cracks and bulges. No mold growing on the inside and I don’t smell any. I really appreciate your response and all the info you provided. Thanks!