Recaulking is one of the projects that most homeowners have tried at one time or another. But caulking yet remains to be one of the most tedious projects, First and for most, lack of proper caulking has become the #1 reason we get a call. It has led to the highest water damage issues we've seen. Before a tub or shower becomes caulked it needs to be properly prepped, all the old caulk has to be removed. No! Caulk can not be caulked on existing caulk. and if applied inside a shower it needs to be 100% silicone. The area that is being caulked needs to be clean and 100% dry. Caulk will not dry properly if applied on a wet or moist surface, caulking it will cause it to crack or turn moldy. It is best to have a professional caulk all your surfaces because, too much caulk is not good, and it is more susceptible to impact, which will loosen it. And to little caulk will not have a proper bond.