u/DJThadyus

My mom and I bought this house about a year ago and most stuff they had fixed but not fixed right. I noticed this in my shower at the bottom where it had not been sealed properly…tore it apart today to hopefully just reseal the tile and found all of this?

The wood studs behind seem ok but definitely need to dry out.

The drywall backing is falling apart, wet and moldy. But it looks ok the higher you go up as you can see in the pictures…started taking the next level up.

What should I do? Any help would be appreciated!

Can I do this myself? If so what can I fill in with the backboard for the bottom layer?