Is there a waterproof primer/sealer for painted sheetrock?

Faye...May husband used a moisture resistant sheetrock in our basement when we went from paneling to sheetrock. He purchased from Lowe's. He says it's similar to what is normally used on bathroom walls in building. I don't guess I actually answered your question as it appears you already have the sheetrock but I do know they do have a Zinsser product called Gardz from Amazon that might help with what you have. Good luck!

Faye,

I have used Gardz. It makes a good sealer and primer, but it is not waterproof, just water resistant. Google how to waterproof sheetrock. There are special paints and products to achieve that.

They make a rubberized paint on substance to use in bathrooms before tiling.... https://www.youtube.com/watch?v=ehfTrvTRPvk Redguard or Kerdi

Hello Faye, there is "greenboard" that is water proof, I have attached a link for you to read over which discusses green and blue drywall sheets

https://www.doityourself.com/stry/greenboard-vs-blueboard