Yesterday and today's project, cleaning and sealing behind the bottom row of ceramic tiles around the bathtub. I had removed the old caulk between wall and tub a couple of months ago, but never got around to resealing it.
This got me to worrying about mold buildup behind that bottom row of tiles, so I pulled that row of tiles out last night and cleaned up that area. There was some blackness that had started in that area, so I'm glad I did that. To kill any mold, I sprayed the area first with Hydrogen Peroxide, then later with vinegar. (Articles I read suggested not to use bleach because it won't attach porus areas.)
Home construction so old that they didn't use concrete backer board like today, but was just drywall that was also deteriating somewhat, but not enought to have to replace it. I just scraped off the lose material.
Then to seal up the tub to the wall, I used a tube of plasic roof cement that looks and smells like asphalt. Later today I'll go buy some tile cement and glue the pieces back on. A few broke. There's an old box of them I found in the house that I can cut (somehow) and use them instead. Then re-grout and caulk.