Drywall / Sheetrock bubbles or blisters
I have a question that no one can answer. And I cannot find any info in the internet because all of the search results say 'nail pops" but I don't think they are. In my condo, I have about 40 round drywall bubbles. These are all consistently the diameter of about 1" or a little over and occur where the nails are.
I also have some nail pops which are about a half of an inch in diameter.
These bubbles sound hollow when I tap them with my fingernail. At first I thought the mud was separated from from the dimple, but when I cut a bunch open around the perimeter of the bubble, the bubble is actually under the drywall paper/skin just to the side of the nail. "Paper/skin separated from the rock/gypsum. Nails, are solid and look properly dimpled. Still tried punching the nails in but bubbles are still there.
What is the proper way to fix these?
But, more importantly, what the heck caused this? Those bubbles where there when the condo was brand new! So I don't think it's due to settling.
Thanks so much!