One of the most common problems for leaks or mold and mildew in a bathroom begins with a moisture getting out due to faulty or decaying caulk in your shower. If a tub or shower is not properly sealed, the moisture that gets out will continue to cause problems in your bathroom. Caulk is an inexpensive weekend project that can take just a few hours to complete.
Caulk works because it is both a strong glue and a flexible sealant, this is critical in order to seal a joint between dissimilar materials or a joint that has movement. In the damp environment of a tub or shower, you need the right kind of caulk that keeps the water where it belongs and protects your home.
Removing old caulk should be done annually in every bathroom. Many homeowners will fix this problem by recaulking over the existing caulk rather than replacing it. This creates more problems down the line since you're just putting a band-aid over an existing problem.
Your first step is to remove all the existing caulk. A 5-in-1 painter's tool and a razor scraper might be all you need. A utility knife will also work. Make sure to use a plastic blade as metal can scratch the tile. There are also caulk removal products that will pre-soften the caulk, to make the removal easier.
As you remove caulk, mold or mildew might be under the surface. Apply a mildew cleaner or make your own. A one quart liquid bleach and three quarts warm water mixture with 1/3 cup of powdered laundry detergent is an easy, homemade solution. Spray your mixture on the mold and let it sit until it begins to fade, then rinse with water. If you notice any large amount of mold or dry rot, you should contact a professional to make sure there is no serious damage.
Once all the caulk has been removed and the area cleaned, make sure the joints are free of caulk dust by going over each seam with a damp rag or sponge. Go over all the areas with a cloth afterwards to make sure the seams and working surface are completely dry.
Lay a strip of blue painter's tape above and below the caulking joints. This will help adding the caulk neatly - especially helpful if it is your first time using it. Trim the nozzle at a 45-degree angle near the tip so it's big enough to fill a joint. Point the nozzle of your caulk gun towards the joint and apply steady pressure as you place new caulk into the seams. Don't go too fast or too slow, as the caulk might not come out evenly. Keep the caulk moving at a steady speed.
Once you've filled every seam, go over each with a damp rag, paper towel or the back of a spoon, applying pressure to be sure the caulk is setting in. Remove the painter's strips taking care not to touch the caulk. Wait at least 24 hours before using the shower or bath.