I had hired a flooring company to replace vinyl with new tiles. When they removed the underlayment, it turned out there was some mold on the subfloor near the tub (see pics). The flooring guy said that they cannot fix it because the tub needs to be removed.

Should I find someone to fix it or just lay new tiles on top without fixing it?

Do I need to remove the tub to fix this?

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  • The only recommendation we can make is "yes you should". See isherwood's comment for reasons you might choose not to. – FreeMan Sep 11 at 11:38
  • @isherwood I don't think its off-topic. I am simply trying to consult people what would be the recommended next step. – TriCore Sep 12 at 4:34

My suggestion

  • paint the mold with Javex and ventilate room with open window until white and dry, the. Scrape residue to hard clean surface, vacuum clean up and seal tub well.

Ensure tile grout is seal coated for moisture resistance.

Then get 2 more quotes.

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It is hard to tell if the floor has rot or if that is just mold.

If this is just mold confined to the top layer of your osb and the osb seems structurally sound I'd probably:

  1. wear a mask, turn the fan on, get a bucket of bleach water and some shop paper towel, wear gloves, aggressively scrub the area with shop towels. I'd probably get a plastic wire brush that is used to clean floors and do that as the second pass.
  2. dry the area, use a heater and or dehumidifier to dry the area after you've cleaned it.
  3. get a wire brush and brush any areas that still look like they need more work, sweep it up and bag it.
  4. paint the area with a mold killing primer/sealer. killz or zinsser.
  5. tile, use epoxy grout, use a silicon caulk to seal the tile to the tub.

Mold itself isn't dangerous it is the airborne mold spores that aren't good for you. If you did nothing and sealed it in the floor it would likely be fine as well. The concern with that is that the thin set wouldn't properly bond to the area with the layer of mold.

Also note mold in that bathroom is probably the least worrisome as you spend the least amount of time in that room.

Ripping the tub out would make that job 3x harder for little real gain. If the floor has significant rot then you cut the piece of flooring out, add nailers and patch it. I can't imagine pulling the tub unless the joists under the subfloor were significantly rotten - even then I'd sooner pull the ceiling below (assuming the tub is otherwise nice and the tile job is good).

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  • I agree (+1) except that you can just spray the mold with bleach/water solution to kill it. You don't have to physically remove it once it's dead if it will be covered with tile. So, no need to scrub or wire brush the area. – Jimmy Fix-it Sep 11 at 5:39
  • I'd worry about the mechanical bond of the thinset to the substrate if you just bond the thinset to the layer of dead mold on the surface of the osb. It would be like bonding thinset to dust, the dust with cover the adhesion and the thinset will have no bond to the substrate (osb) and will eventually lift off. – Fresh Codemonger Sep 13 at 0:40

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