The nasty bathroom floor demo.

Tearing out the water logged MDF flooring

This whole process took me about a week. I spent every minute I had on this dreaded job and it was almost enough for me to just say forget it and burn it all to the ground. For starters this was MDF that had been kept moist, I don't know what you know about MDF but it's the same crap that Wal-Mart furniture is made of. Once it gets wet it swells, then dries, then makes me want to kill. To top it all off, these boards were screwed, nailed THEN glued to the 2x6 floor joists so I couldn't just lift it off, no no no. I had to break all the funked up MDF then try to chisel the glued on junk off as well. I bought chisels, tile lifting tools, sharp bars but found that my wrecking bar+ a ball peen hammer worked best. Then I got mad and hit it with my belt sander and 80 grit paper. It was faster but the dust was terrible.
Before I tackled this job I asked a GC to come over and tell me what I was dealing with. Black mould? He told me that he didn't think it was black mould but I wasn't risking it so I was wearing two particle masks and goggles the entire time I was doing this tear out in the bathroom.
With all the MDF out and many many many runs over the underlaying surface with my trusty shop vac I was starting to feel much more satisfied. I also used four litres of bleach on this whole surface just to scrub more funk off and also a bottle of mould inhibitor for extra assurance. By this time with all the chunks out of the trailer it no longer smelled of gross, but rather it was smelling like timber. Nice non-rotten timber.
Booya! I layed that piece of 3/4" OSB subfloor at about midnight just to give me a feeling of getting somewhere again.
After I added the insulation I carefully added a new layer of poly under the joists then run some new PEX lines that feed the hot/cold in the kitchen. I replaced the P-trap for the shower as well.