We have a surround in our bathtub that needed recaulked. There was a section of caulk that had gotten a hole in it and was causing water trapped behind the caulk to run out of the tub and onto the floor. We have 2 problems as a result of this. 1) We recaulked the entire tub and let it dry for 24 hours, but the caulk keeps cracking within a few days and then disintegrates from water getting into it (this is in a different area of the tub than the original problem). 2) Right outside the tub there are a few tiles going vertically down with a small piece of quarter round board at the bottom as trim. I notice a mushroom growing up from the wood. We pulled the piece and left the spot open to dry for a few days, and I noticed another mushroom. What in the world can we do? I just seems like we can't get it dry enough in the bathroom no matter what we do.

It sounds like you might have a leak in behind the tub as well, which will stop the caulking from adhering properly. Dry it out and run the water without actually showering and see if the floor area is still getting wet.

I believe you are not drying the area good enough, here is what you need to do,
Remove the old caulking and start from scratch. Here, dry all up, then you apply some rubbing alcohol to the area to be caulked to speed evaporation and to increase the ability of the caulking to adhere to the shower tile/base, etc.

I would also recommend that you use a hair dryer to speed the evaporation if moisture is present apply alcohol, let evaporate, dry area a bit with a hair dryer, let dry overnight, apply alcohol again and then let that evaporate before applying the caulk.

In my opinion, the very best caulk forTub/ showers is 1 HOUR SHOWER READY CAULK, open the link below, Good luck.

John

GE Silicone II* KB Supreme

Fresh caulk does not crack, are you using silicone or grout? If you have a mushroom you have significant moisture there and that needs to be fixed and then apply a mildewcide or 1:1 bleach water mix.

I would suggest that you stop using the shower/tub completely for period of one week. Keep windows open so any wetness will dry. Then, buy Denaturated Alcohol. Put it in a spray bottle. Spray it over the area you want to caulk. Go over it immediately with dry, clean cloth. Wait 10 minutes and then caulk with latex or silicone caulk. Do not use the shower/tub for another 3 days.

Latex is lot easier to use than silicone caulk. Silicone requires some practice. Latex, you can clean with water and you have more time to smooth it. With silicone, you have very limited time. If you still want to use silicone, than I suggest that you practice on similar surface first.

We have not heard back from JW so it's a rough call. I suspect JW is not using silicone caulk nade for sinks and tubs, may well be using grout in error.

We are not using grout. It is caulk made for sinks and tubs. Thank you to John. Your suggestion about the rubbing alcohol seems to be the most useful since I can't refrain from using this bathroom for long periods. We're also going to put a dehumidifier in the room to help dry it out.