Solid Hardwood, Engineered and Laminate Flooring - bathroom floor damage

I have removed old linoleum to find water damage to the subflooring around the toliet rim and near one corner of the tub. The plan is to check out the condition of floor joists, replace the toliet's wax ring and pull up that section of damaged subfloor, etc. However, my friend tells me there is a treatment that can penetrate that damage, stop any rot (wet or dry) and set up into rock-hard wood. He thought it might be some type of liquid epoxy or maybe even fiberglass. -- Sounds like a dream. Anyone know of such a treatment?

A job worth doing is worth doing right. If it sounds too good to be true, it probably is!

You need to pull up the rotten subfloor and inspect for additional damage and make any necessary repairs. While you have the toilet pulled, go ahead and install new floor covering before resetting the toilet.