Anybody can recaulk a tub or shower. All you need is a tube of caulk and a caulking gun. But if you don't prep the surfaces properly, the caulk won't last long. And if you're sloppy, the messy caulk job will ruin the look of even the most beautiful tile job. We talked to a few experts to learn how they get such smooth, clean-looking caulk lines, and we'll show you their technique. And we'll show you the best way to remove the old caulk and prep the surface to get a long-lasting caulk job. Finally, we'll give you a heads-up on how to avoid the most common caulking mistakes.
You can remove the old caulk, prep the surface, and recaulk a tub or shower in about four hours (including drying time). You'll need a razor scraper and single-edge razor blades, caulk remover, mineral spirits, paper towels, a utility knife, a caulk gun, and kitchen and bath caulk. An oscillating tool with a flexible scraper blade really speeds up the job of removing old caulk, but you can do the job without it. Here's how to start.
Tubs and showers require a special caulk that contains mold and mildew prevention additives. The tubes are usually labeled “for kitchen and bath use.” Most are 100 percent silicone, but you can also find some latex versions. Latex caulk is easier to tool and cleans up with soap and water. If this is your first time applying caulk, latex may be your best option. Silicone is more challenging to tool and requires mineral spirits for cleanup. However, silicone lasts longer than latex and stays flexible over its life. But it's harder to remove when it's time to recaulk. Both types can develop mold and mildew once the additives wear out.
Most home centers and hardware stores stock only three kitchen and bath caulk colors: white, almond and clear. However, ask a salesclerk whether you can special-order a custom color. And check out a paint or hardware store. Some can custom-mix colors right in the store. Most tile stores will carry a full range of colors.
A high-quality caulk gun can make a difference in your caulk job. It has a sturdier plunger mechanism to provide a smooth, even flow and a pressure release to stop the flow quickly. High-quality caulk guns cost a bit more (about $15), but they're worth it. Economy guns usually have a ratchet action or a sloppy friction mechanism that pushes the caulk out in bursts, so you apply too much in some areas and too little in others.
You can't apply new caulk on top of the old and expect it to last. So the old caulk has to go. If the old caulk was silicone, you have to devote extra effort to remove all traces of it before applying new caulk. Start by slicing through the old caulk with a utility knife or an oscillating tool (Photo 1). Then scrape off as much old caulk as possible. Next, apply caulk remover to break the adhesive bond and make it easier to scrape off (Photo 2).
Once the old caulk is gone, remove any loose grout between the walls and the tub or shower floor. Treat any mold in the grout along the wall/tub gap with a mold-killing product. Scrub the grout and then rinse off the mold killer with water and let it dry (use a hair dryer to speed the drying). Clean the surfaces one last time with mineral spirits. Let dry.
Some pros scoff at the idea of using masking tape. But they caulk every day and can lay down a caulk bead with their eyes closed. For DIYers, we recommend masking the gap. It takes a bit more time, but you'll get much better results than caulking freehand. Start by finding the largest gap between the tub/shower and the walls. That gap dictates how far apart you must space the two rows of tape. Then apply the masking tape (Photo 3). If you have a fiberglass or composite tub, you should fill it before you caulk.
Avoid These Caulking Mistakes
- Buying the wrong caulk. Always use kitchen and bath caulk in a tub or shower. It contains mold and mildew inhibitors that are not present in other types of caulk.
- Caulking on top of old caulk. New caulk doesn't bond well to old caulk, especially if the old caulk contains silicone. Just like with painting, better surface prep provides better results.
- Not removing mold on grout near the caulk areas. Grout is porous, and any mold present in the grout above the caulk line will eventually spread down into the new caulk area and destroy the bond.
- Cutting the nozzle larger than the gap you're filling. A larger opening applies too much product, making it harder to tool and clean up.
There are two schools of thought when it comes to tip angle and whether to pull or push the caulk. Our experts prefer cutting the caulk tube nozzle at a blunt 20-degree angle, instead of 45 degrees. And they hold the gun at a 90-degree angle to the gap while pushing a small bead ahead of the tip (Photo 4). That way, they can complete the entire bead in one pass. Plus, the gun pressure forces the caulk deeper into the gap for better holding power and sealing.
If you cut the tip at a 45-degree angle and pull the gun away from the starting corner, your gun will always run into the opposite corner, forcing you to flip it 180 degrees and start the bead again. That creates a blob where the two beads meet, making tooling more difficult. Plus, pulling the gun tends to apply a surface bead that doesn't penetrate as far into the gap.
Whichever tip angle you choose, always cut the tip with a sharp utility knife rather than the cheesy guillotine mechanism built into some caulk guns. Remove any burrs with a utility knife or sandpaper before caulking—the burrs will create grooves in the caulk lines.
You can find all kinds of caulk-shaping tools at home centers. But if you take our advice and tape off the wall, you won't need any shaping tools. Just use your index finger to tool the caulk (Photo 5). After tooling, remove the masking tape while the caulk is still wet (Photo 6). Let the caulk cure for the recommended time before using the tub or shower.