After the demolition of our shower, I noticed our shower floor was water proofed with a hot mop method. This is all new to me (never even heard of hot mopping), so I was wondering if we need to completely remove all traces of the tar residue. Or, if we can simply cover it with our new water proofing? We plan to pre-slope with deck mud, add liner on top of that, then post-slope with a light concrete mix, use RedGaurd, etc..
If you look at my images, I was able to remove the liner and most of tar, but there is a square around the drain left where I assume they did extra. I tried chipping off as much as I can, but I couldn't get it all off. I'm trying to be careful to not damage the plywood subfloor underneath to avoid having to replace it since it is not damaged and I'm really trying to limit unnecessary changes if possible. We plan on redoing the shower curb and wood around the base in between the framing (not sure what it's called), so the tar on those items will go away. However, we want to avoid doing anything to or replacing the subfloor if possible.