Tile grout along seams and corners of bathtubs and shower enclosures is usually thicker than that found between tiles, making it vulnerable to cracking and breaking. These gaps should be repaired to prevent moisture from migrating into walls, framing and flooring. Rather than re-grouting — a time-consuming task that requires a certain amount of skill — many homeowners simply caulk affected areas.

 

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Caulk also is used to seal the bottom tracks and side rails of shower-stall doorframes to the enclosure, helping to keep water inside.

Choose all-silicone caulk, sold by home centers and hardware stores, when repairing a tub or shower enclosure. It’s usually labeled for use in kitchens and baths. Silicone caulk is not paintable, but remains flexible over a wide range of temperatures. It doesn’t shrink as much as latex caulk as it dries, and once cured, it will last longer, too. Silicone forms a barrier against deeply embedded mold, mineral scale and soap scum, although all three may form on its surface. Most silicone caulk is either white or clear.

Silicone caulk can stand up to repeated cleanings with even harsh chemicals such as chlorine bleach and mineral-scale removers. Avoid the use of abrasive pads or brushes on silicone, which will roughen the surface and make future cleaning more difficult. Soft nylon brushes or white pads should be OK for persistent soils as long as you’re not too aggressive while using them.

Unlike latex, silicone caulk gives off strong fumes as it’s being applied. Ensure plenty of fresh-air ventilation through the bathroom and wear latex gloves when applying this caulk. Surgical-type gloves will allow you to smooth the caulk bead after application using your index finger. Have several squares of paper towels handy to wipe up and discard excess caulk.

Before replacing worn-out caulk, use a utility knife to remove all old caulk. The repair will look better when finished, and it’s easier to apply caulk to a clean seam.