Bathtub Caulking: What Types of Caulk to Use

One of the most important aspects of bathroom maintenance is keeping water out of areas where you don’t want it to collect. Proper building materials like tiles, water-resistant drywall, and a good ceiling fan are important aspects to keeping mold and moisture at bay, however, it’s the caulking that is the silent hero of preventing water damage.

This gooey material generally comes in tubes and is applied as a bead that runs along seams where two materials meet, creating a watertight seal. Most notably, caulking is used where tile meets a bathtub, in corners of shower walls, and along the vanity sink where it joins up with the wall or backsplash. But not all products are made the same and knowing what kind of caulking to use in your bathroom is paramount to having a long-lasting application.

Types of Caulking

The caulking section of the hardware store can be daunting as there are a multitude of applications. Keep things simple and look for specific “Kitchen and Bath” or “Tub and Tile” caulking. They are best suited for these types of rooms where water is more prone to get between two surfaces. It’s easy to get overwhelmed by options and while some other kinds of caulk may say they are good for creating a waterproof seal, they may be manufactured for marine use or exterior surfaces.

These will not be good options for your bathroom as exterior caulking is thicker and meant for larger seals that will not “finish” well for an interior application. Kitchen and bath caulks are silicone or latex-based, and while both will stick to tile, bathtubs, and sinks, they each have very different dispositions.

Silicone Caulking

Silicone is very strong, yet flexible, which makes it ideal for the bathtub area where various weight distribution creates movement where the tiles meet the tub. Although it's waterproof and flexible, silicone can be extremely difficult to manipulate. The bead must be applied in one continuous run and once it's set you really only have one chance to wipe it smoothly, otherwise things can get real messy as it is extremely tacky and does not clean up with water.

If any silicone is smeared on a surface you don’t want, the best way to remove it is with mineral spirits and a semi-abrasive pad. Note that it’s not always guaranteed that it will come off at all, so a well-executed initial application and quick clean-up is crucial.

Latex Caulking

Latex cleans up easily with a rag and water if a bead runs wild or you get some on an unwanted area. You can apply touch-ups when it’s still wet, giving you a much more forgiving window of time to get that perfectly smooth bead around the tub or sink. The downside is that latex is not as strong as silicone and will shrink and dry harder, making it prone to cracks and gaps where water can enter.

So, while the application process is much easier than silicone, you most likely will have to replace the latex caulking a lot sooner. Keep in mind that latex leaves no smell, whereas silicone can sometimes have a very strong odor, and both have different drying times depending on the manufacturer.

Choosing a Color

Latex caulking can be painted once it dries, allowing you to cut your paint lines in nicely around the vanity sink and any window or door trim in the bathroom. Silicone will not take to any paint, not even oil-based products. In fact, it's not meant to adhere to anything once it cures, including fresh silicone. It doesn’t come in as many colors as latex either, so you may decide to use latex in some areas where color matching is important.

Both will come in the standard white, clear, almond, and black options, which are usually sufficient for most rooms. A good rule of thumb is to match the caulking exactly to the color of the tub, toilet and sink—white to white, black to black, etc. It’s best to keep the type and color of caulking consistent, so at the very least try to use the same tube for the shower and bath area.

Caulking Strips

Another product on the market that appeals to some DIYers is the self-adhesive caulk strip. In theory, they are meant to relieve the stress of applying silicone or latex caulking properly, however, they can be just as tricky to get right. They have a bead of silicone adhesive already placed on a plastic strip, which you place against a seam. While it claims to be simple, getting the top and bottom to fully stick to the surface is not guaranteed, leaving gaps for water to seep and pool. Also, they are somewhat unsightly, as the plastic strip is thicker than a regular bead of caulking (which should be no more than ¼”) and will create another edge rather than a smooth seal. If you have a large gap to cover these might do the trick, but for regular applications it's recommended to use the kitchen and bath silicone or latex caulking tubes.

When deciding on what bathroom caulking to use, the first step is to find the right product for the job. Second, get to know the various ways that silicone and latex apply to the various surfaces in the room. While either will do the job, you may want to try them out to see which one you are more comfortable using. It may seem like a small task, but creating a proper seal is not only tricky to master, but essential for keeping water from seeping into unwanted areas. At the end of the day, you either have to get the hang of it or hire someone who does.