I’m getting ready to install LVT over existing VCT in my bathroom, and when I pulled up the shoe molding I discovered that the corner of the floor next to the shower has a slight soft spot at the very edge, with just a slight give when I press my finger in the very edge of the corner. The radius of the give is well under an inch, and the deflection no more than 1/8 inch down. It’s not wet so it seems like it must’ve been this way for a long time, and perhaps some cracking caulk for where the shower had been sealed long ago is to blame. There is also some evidence of a small amount of mold.
I’ve treated the mold with vinegar, but do I need to pull up the floor and repair this small spot? It won’t be noticeable once I’ve installed the new floor, and if I take care to seal it well, do I still need to be worried about it getting worse some how?
Update: I peeled up the flooring to reveal the extent of the damage to the wood subfloor, and the top layer was a little crumbly but it’s solid underneath (see photo). Would it work for me to just patch it up now? Any recommended patch strategy?