You do not want to caulk over grout in shower corners. Silicone caulk used for bathrooms will not bond well to grout. This will result in peeling caulk and an infestation of mold and mildew between the caulk and grout. The best course of action is to remove the old grout in the shower corners and then apply silicone caulk. This will achieve a professional, long-lasting seal.
Table of Contents
What Happens When You Caulk Over Grout?
If you caulk over grout lines, you will only temporarily fix cracked grout. You will also create the circumstances for a mold and mildew invasion in your shower. Caulking over grout is only a temporary fix because caulk forms a poor bond with the more porous grout. Whether it takes a few months or a couple of years, the caulk will start to peel off the grout.
- Caulk over grout will peel off over time because caulk will not bond well with grout.
- Mold can form between the caulk and grout.
- Mold that begins in your shower can spread to the walls behind the tile installation, causing damage to your home.
Because grout is water-resistant, not waterproof, moisture will be trapped between the caulk and grout, causing mold to grow there. This will be extra apparent if you use clear silicone caulk. You will actually begin to see mold growing under the caulk, where you can’t clean it. This mold can spread to your wall, causing damage to your home.
Why Should You Use Caulk in Shower Corners?
It’s essential to use caulk, not grout, in shower corners. Grout does not hold up well in corners and is prone to cracking and falling out. This is because the tiles on the two perpendicular walls expand and contract with temperature changes. The grout will not flex to match these changes, leading to cracked grout in corners. Silicone caulk provides a flexible waterproof seal and ensures crack-free shower corners.
- Grout in shower corners will crack and fall out due to tile expansion and contraction.
- Caulk forms a waterproof, flexible seal in shower corners.
- Always use caulk in shower corners or any place where the tile meets another surface (tub edge, wall, or faucet).
When sealing your bathroom, use caulk in corners and wherever the tile meets a non-tiled surface. This includes walls, floors, tubs, and metal plumbing fixtures.
7 Steps to Remove Grout and Caulk Shower Corners
If your shower corners are grouted, they’re likely to be cracked, chipped, or mildewed. Rather than caulk over them, remove the grout. Then, caulk the seam. This process can be done easily and will yield durable results.
Cut Grout with an Oscillating Tool
The first step in removing old grout from shower corners is to cut it out using an oscillating tool fitted with a grout removal blade. Gently guide the tool, allowing the blade to do the work of breaking up the grout in the corner. An oscillating tool is great for this job because it is gentle enough to break or loosen surrounding shower wall tile.
- Use this oscillating tool to cut through grout in shower corners.
- These grout cutting blades for your oscillating tool will make quick work of old grout.
- If you don’t have an oscillating multi-tool tool, a rotary cutter (Dremel) can be used to cut through old grout.
- Do not use an angle grinder to cut grout. It may damage nearby tiles.
If you do not have an oscillating tool, you can use a rotary cutter tool, such as a Dremel, to cut through the grout. Both oscillating tools and rotary cutters are gentle enough for detailed work and will not ruin your tiles. Avoid using a high-powered tool, such as an angle grinder, for this task. High-powered tools can cause hairline cracks in nearby tile as you cut through the grout.
Get Rid of Stubborn Grout
If any grout remains after the first step, use a grout-remover tool to complete the job. A grout-remover is great for scraping out loose chunks of grout, as well as removing stubborn grout that clings to the side of tiles.
- This hand tool is great for removing grout left behind after you’ve used the oscillating tool.
- A hand tool for removing grout can clear out loose chunks and stubborn grout in corner seams.
- Work carefully to avoid chipping or cracking tiles.
When clearing old grout of seams, avoid putting pressure directly onto a tile to make sure you don’t crack it. Also, do not pry or twist with the tool, as this can loosen tiles. By keeping these guidelines in mind, you can remove grout by hand without doing any damage to your shower walls.
Tidy Up Formerly Grouted Seams
In many cases, you will entirely clear old grout after you’ve used your oscillating tool. However, if the original grout job was messy, some residue may be left on the tile’s surface. For this, use a scraper equipped with a razor blade to clean grout residue. Clean, grout-free corner seams will ensure your caulk bonds seamlessly to the tile.
- Use this razor blade scraper to remove any remaining grout residue from tile surfaces and seams.
- A clean corner seam provides a better bond between caulk and tile.
Once you’ve removed all the grout from the corner seam, the hardest work is done. This prep work is essential to creating a good-looking and functional caulk job that will match the work done by a tile professional.
Clean Up After Grout Removal
Following grout removal, wipe the tiles with a damp cloth or sponge to remove any grout dust. You can also take this opportunity to vacuum up any bits of grout that fell into your shower pan.
- Wipe the shower seams with a damp cloth or sponge to remove grout dust prior to caulking.
- Vacuum grout pieces out of your shower pan or tub.
- Do not directly spray the cleaned seam with water or another liquid.
Do not use the shower or another source to spray water directly into the corner seam to clean it. Without any grout or caulk in place, it is very easy for water to infiltrate your wall and cause moisture damage.
Caulk the Corners
Use a caulk gun to apply a bead of silicone caulk to the corner seams of your shower. Silicone caulk is the perfect material for showers because it will not shrink or crack over time. This means it will not harbor mold.
- Caulk shower seams with silicone caulk.
- Do not use latex or other non-silicone caulk compounds.
- Use this color-matched silicone caulk so your corner seams match your other grout lines.
For the best appearance, use a color-matched silicone caulk. Silicone caulk can be found in a wide variety of colors, making it easy to match the caulk to your grout. This way, the caulked seams blend in with the rest of your tile work.
After applying the caulk to the corners of your shower, smooth the bead of caulk with a caulking tool. This will create a smooth, uniform appearance to your caulk. It only takes a moment and prevents any lumpy or abnormal caulk lines.
- Use this caulking tool to smooth out the caulk lines in your shower corners.
- For extra precision, tape off the shower corners, then remove the tape after caulking and smoothing.
If you would like extremely precise caulk lines, adhere blue painter’s tape to the tile on either side of the corner before caulking in step 5. After smoothing the caulk, remove the tape for a professional finish.
Allow Caulk to Dry
Wait 12–24 hours after caulking before you use your shower. This allows time for the silicone caulk to cure fully. While 24 hours is best, if you don’t have access to another shower, 12 hours of cure time should be sufficient.
- Allow 12–24 hours for caulk to fully cure before using your shower.
- Using your shower too soon could ruin your caulking job.
Silicone caulk may seem waterproof right after you apply it, but a spray of running water can ruin the hard work you put into caulking those shower corners. To ensure a perfect seal between the caulk and tile, wait for the caulk to cure.
Can You Apply Silicone Caulk on Top of Grout?
While it’s possible to lay a bead of silicone caulk over grout, the results will be poor. Not only will the caulk line appear messy and unprofessional, but the caulk also won’t bond well to the grout. Caulking over grout will lead to peeling caulk and will likely cause a colony of mold spores to grow between the caulk and grout. To achieve a good-looking, waterproof seal, remove the grout and apply silicone caulk in shower corners.