Sunday, October 17, 2004

The secrets of tub caulking

[IMPORTANT NOTE: An updated and more detailed version of these instructions is posted at:]

The caulk between the tile shower walls and the bathtub gets mildewed and every year we try to come up with a better way to replace it.

First year: Throw money at it
I called a bathtub re-caulking service recommended by a local consumer group. They sent two teenagers to futz around in the bathroom for a few hours, charged more than $300, and told us to keep the shower curtain open (between showers) to promote air circulation. Well, duh! We installed a more powerful bathroom fan that sounds like a 747 taking off four feet overhead. Neither of these strategies prevented the mildew from returning in a few months.

Second year: Do it yourself--twice
Inspired by several do-it-yourself articles, I prepared to recaulk the tub myself. Since the damp, mildewed area behind the removed caulk must be treated with a bleach solution and then thoroughly dried, and the new caulk must have time to cure without moisture, this involves taking showers in our other bathroom. Unfortunately, that's a tiny upstairs shower stall tucked under the eaves, and the shower head only comes up to chest level on my husband.

So I waited until he had gone on a long mountaineering trip to start the process. I peeled off the caulk with a special plastic hooked tool, and applied the bleach to the grout in the mildewed area. I noted that the grout hidden by the caulk was not only mildewed but crumbling, and took out decayed sections. This worried me, and I consulted a few of my handyman friends to see if I should re-grout before re-caulking. The concensus was "no," so I forged ahead (mistake #1). The last step in the process involved applying the silicon caulk (a tube purchased at the local hardware store--mistake #2) and smoothing it with a little plastic caulk-smoothing tool. It was much stickier and messier than I had imagined, the caulk rapidly drying and getting tacky. Of course, it was a this moment when the phone rang. My husband was calling from the mountain top. Holding the phone with the backs of my wrists while caulk got into my hair, I tried to sound enthusiastic for five minutes (fatal mistake). By the time I got back to the bathtub, the caulk looked and felt like day-old chewed bubblegum; there was nothing smooth about it. I carved off the excess glop with a razor blade, then called a handyman friend and made plans to start the whole process from scratch when my husband went on his next mountaineering expedition. For round 2, I removed the glop with a razor blade (an evening's work) and the next day my friend came and applied the silicon caulk. "It's not great," he said. No argument from me. But it looked slightly less blobby, and cost much less than $300. The mildew returned, on schedule, a few months later, despite fans and cleaning efforts.

This year: the grout/caulk combo and the miracle of dish soap
Fortified by more do-it-yourself articles, I stripped the ghastly mildewed caulk, bleached, and then panicked when I saw even more disintegrated grout. I called the experts at the local tile store. Could they recommend a subcontrator to apply new grout and caulk for me? The tile person snorted like a sommelier at the Four Seasons being asked for Kool-Aid and said they did not know anyone who would be interested in such a small job. He suggested that I call a handyman. I informed him that I could do just as crappy a job as a handyman myself, and I didn't want a crappy job. He started to laugh, and told me to come over to the store to get a good grout and a special professional caulk instead of the stuff from the hardware store. That night my husband came back from a trip out of town to find the tub devoid of caulk. The "when can I use the shower?" clock began to tick, loudly.

The next morning I went to the fancy tile shop and a salesperson listened to my tale of woe. She told me there is a grout/caulk combo used by professionals that looks like sanded grout and is extremely good at filling spaces and keeping a tub wall watersafe (tip #1). She handed over the sanded grout/caulk (a mere $9) and told me to put it on and smooth it. She recommended dipping my finger in a mixture of water and a bit of dish soap to really make it smooth (tip #2).

The good news is that her technique worked. But it wouldn't have worked as well if I hadn't followed advice from one of the articles and masked the area to be caulked, 1/8" up the wall and 1/8" on the tub, using wide painter's tape (tip #3). My own touches included 30 latex medical gloves (available in bulk at your local drugstore) and a large grocery bag. You'll see why. Here's the drill:

[IMPORTANT NOTE: An updated and more detailed version of these instructions is posted at: I suggest you refer to the new version instead of the following.]
  • Make sure the area to be caulked is clean, bleached, and dried and all traces of loose grout and old caulk have been removed.
  • Tape the area to be caulked, as described above.
  • Apply the grout/caulk bead using a good caulk gun.
  • Place the grocery bag next to tub.
  • Using a series of latex gloves and dipping your finger in a small container of water with a little dish detergent, begin smoothing the caulk bead. If glove gets gunky with caulk, put on a new glove. Otherwise, you will smear caulk on everything. Dump sticky gloves into grocery bag.
  • Once the bead is smooth, remove tape from the tub side of the caulk line and dump the tape into the grocery bag. The do-it-yourself article didn't mention that there will now be a bit of a raised edge on the caulk where the tape was removed. Get out the gloves and start smoothing that border flat. Then remove the tape from the wall, put on more gloves, and smooth that border.
  • You may also want to grout/caulk a few inches up the inner corner (or corners) of the show stall. Apply a short bead of caulk, and smooth to join the main caulking.
  • Recap your tube of caulk with plastic wrap and tape. Dump bag of trash. Wait 72 hours, then enjoy.


  1. THANK YOU. i have been fighting this battle for a long time! I was just getting ready to use the cheap caulk from a tube. I am thinking that i should go get the good stuff and do it right!

  2. Thank you for the tips. I will use the tape and the good stuff. My problem is the 5/8 inch gap between the bathtub and the tile on the long wall. The caulking keeps falling through. Any suggestions?

  3. That hole (gap) needs to be filled before you caulk. I'd fill it with traditional group (not caulk) and let that dry thoroughly (a few days) before you caulk.

  4. THANK YOU!!!!!!!!!!!

    I am so sick of trying to fix the caulk and hiring someone to do what I could have done just as good as I.

    I'm caulking this week. And I shall WIN!!!

    ~carol welch

  5. Anonymous11:28 AM

    Sorry for replying to such an old post, but what is this "grout/caulk combo used by professionals that looks like sanded grout and is extremely good at filling spaces and keeping a tub wall watersafe" you speak of. I have done some searches and have not come up with any such material.

    Would you happen to have a specifics on this material? Brand/Manufacturer/Links/etc?

    respinola -at- gmail dot com

  6. Anonymous10:33 PM

    Anonymous: A lot of grout manufacturers make a sanded caulking that matches the grout. If you do use grout, make sure to seal it grout sealer. That will keep it from allowing water to be absorbed behind the tiles. And then, no more dingy ecosystems popping up!

  7. Anonymous11:59 AM

    I have used this sanded caulk and it is not recommended for wet areas like showers. It will only get mouldy and very stinky at a much quicker rate! Silicone caulking is the only way to go!

  8. Sanded caulk and mold? Not in the case of the caulking I've been buying at the tile store. They're experts, and sell a sanded silicone caulk that is expressly for tubs and showers. I've been using it for years with no problems.