Does it require more skill than muscle to replace a bathroom sub-floor?
There are a bunch of questions from you question, and not a lot of answers. Here is a review of some of the possible situations. What makes you think that it is the sub floor that needs to be replaced? There are a lot of ways tile (and I am assuming it is the ceramic/porcelain variety) has been installed on floors, and some of them were very wrong. If you need to replace the tile because the tile bed (or underlayment) has disintegrated, that is one problem, but it isn’t the sub floor. If your plumbing leaked for a long time and rotted the sub floor (which is under the underlayment or tile bed), that is the sub floor, and it is a very different problem. So, how would you know the difference? If you can look underneath the floor, say from a basement or crawl space, try pushing a flat screwdriver into the floor. If it sinks in like the wood is butter, the sub floor must be replaced. But take a few more seconds to check the joists that are holding the sub floor up. They may be rotted along
