Bathroom Repair Man - bleh.......
About a week ago KeeWee mentioned that the tiled back wall behind the bathtub wasn't looking quite right, and it looked like it was starting to sag inwards. Having just finished my really fun stint as "Furnace Repair Man", I wasn't really looking forward to more home repair projects, but I could see that this needed to be repaired as soon as possible in order to limit the extent of the problem. Time to put on the "Bathroom Repair Man" suit, I guess.
A number of the tiles were loose, and easily lifted off the wall. I kept removing wall tiles with my fingers until I got far enough away from the damaged area that the tiles were still tightly adhered to the wall. The wall board was wet and I was able to poke a hole in it with my finger. I broke off and removed all of the mushy wall board. I could see that the soap dish hadn't been properly sealed and caulked to the wall, and water had been getting behind it and soaking into the wallboard for years. Finally the wallboard just turned to mush. Once I had all of the mushy wallboard removed I set up a heater and a fan in the bathroom to get lots of air movement and some additional heat going to hasten the drying out process. Even so, it took almost three days to get it dry.
Once it was dry I was able to cut out the rest of the damaged wallboard and give myself some straight edges to join up to with the new wallboard. When the house was originally built the wallboard used was "Somewhat water resistant", and as long as you kept water away from it it was OK, but if it got wet you ended up with a mess. They now make a much better product called "Hardi Backer"that is essentially waterproof cement instead of plaster. Although it's good around water, it is a lot harder to work with. I found that the easiest way to cut the stuff was with an abrasive masonry blade in the Skil Saw. It didn't cut it too fast, but it cut cleanly. It also put up a lot of dust, so a dusk mask was absolutely essential. A full respirator would have been even better.
The horizontal piece of 2x10 in the wall between the studs to which the soap dish attached was also rotten and had to be replaced. Getting it cut in half so it could removed without punching a hole through the wall behind it was a challenge, but some careful use of the Sawzall did the trick.
After the replacement Hardi wallboard was cut to size and in place, I screwed it to the studs with the special large headed concrete board screws. I found out that you should pre-drill a pilot hole and countersink the hole so the head of the screw will go below the wall surface. They won't pull into the board as easily as with sheetrock.
Since this is intended to be a waterproof installation, regular sheetrock joint compound and tape won't do. I used the fiberglass mesh joint tape that's slightly sticky on one side (works great on sheetrock, too) and a cement product called "Thinset". Thinset isn't as easy to work with as regular sheetrock joint conpound, but it does the job.
The worst part of the job was scraping the backs of all of the used ceramic wall tile, then grinding off the hardened old tile adhesive. The best method I could find was to use 36 grit sanding/grinding disks on a fairly light weight body grinder. It was a horribly dusty process and it took a long time to individually grind each one to clean off all the old adhesive. After cleaning the backs, I could chip off all of the old grout still remaining on the edges, then wipe down each tile with lacquer thinner for the final cleaning.
The next step was to run a bead of caulk under the new wall board to seal it to the top lip of the bathtub. You need to leave a small gap here to allow for tub expansion, but sealing it with a flexible caulk just adds to the waterproofness.
After the wallboard was in place I noticed a couple of tiles were loose on the left wall under the spout. I peeled off five tiles from the bottom row on that wall, and I could see that a little work was needed here, too. After more drying, I could see that the wallboard was still sound, but that the paper surface had gotten soft and that caused the loose tiles. I carefully scraped the paper from the board and troweled on a thin coat of thinset. Fortunately I only had to grind off and clean five more tiles for this area. When the area was good and dry I spread a thin coat of tile adhesive and let that dry to provide a little more waterproofing. Now it was time to re-install the tile.
Actually laying the tile back onto the wall was a fairly straightforward process, and only took a couple of hours. Finally the tiles were all back in place. After letting the adhesive cure overnight I could cut out the hole for the lower soap dish. They make a special RotoZip bit just for cutting cement board, and it cut the hole without incident. It doesn't cut it as fast as a RotoZip in sheetrock, but still, it got the job done.
Right now the walls are still drying prior to applying the grout and then the final caulking. They figure you should let it sit for at least three days before grouting, but I think I'll give it an extra couple of days as the humidity is a bit high with all the rain we've been getting.
Now you know why I haven't been blogging much for the last week or so..............