Fresh caulk for a cleaner, drier shower
Quick answer
Moldy or peeling caulk cannot be cleaned back to new. It needs to be removed completely, the joint cleaned and dried, and new mildew-resistant silicone applied. A working bathroom fan helps it last.
Caulk seals the joints where tubs and showers meet the walls and floor. In busy households, it wears out in a few years.
When to recaulk
- Mildew stains inside the caulk
- Peeling or cracked lines
- Gaps along the tub edge
Our process
- Remove old caulk fully.
- Clean residue and mildew.
- Let the joint dry completely.
- Apply mildew-resistant silicone.
- Tool a neat, even bead.
Helping it last
A bathroom fan that actually vents outside dries the room after showers. See bathroom fan and vent repair.
Why caulk fails
Caulk fails because of movement, moisture and mildew. Tubs flex when filled, houses settle on hillsides, and steam keeps joints damp. Even good caulk eventually separates.
Glass enclosures
Shower doors and glass panels have their own caulk lines, usually on the outside only. Caulking the inside can trap water. We follow the enclosure maker's guidance.
Tub and floor joints
Where a tub meets the bathroom floor, a bead of caulk keeps splashed water from soaking under the tub.
Toilets
A thin caulk line around a toilet base keeps mop water out, with a small gap left at the back so a leak would still show.
Cleaning routine
Wipe caulk lines weekly with a mild cleaner, and dry the shower after use.
When caulk needs replacing
Caulk is a maintenance item. In a busy shower it typically lasts a few years before it starts to fail. Signs that it is time: black spots that will not scrub out, caulk that has pulled away from the tub or tile so you can slide a fingernail behind it, cracked or shrunken beads, and gaps at the corners.
A gap at the tub edge is worth treating promptly, because water running behind the tub flange can damage the wall framing and the subfloor underneath.
Why mold comes back
Mold that grows in caulk is usually living underneath it, not just on top. Cleaning the surface lightens it for a while, but the spots return. The only lasting fix is to remove the old bead completely, kill the growth underneath, and let the joint dry before new caulk goes on.
Caulking over old caulk traps moisture and mold, and the new bead fails quickly because it cannot bond.
Removing old caulk
Our steps:
- Cut along both edges of the bead with a sharp utility knife or a plastic caulk remover
- Pull out the bead and scrape off the residue
- Clean silicone film with mineral spirits or a silicone remover
- Treat any mold in the joint with a diluted bleach mix, then rinse
- Let the joint dry fully, ideally overnight with a fan running
Take care with acrylic and fiberglass tubs, which scratch easily. Plastic scrapers are safer on those surfaces than metal blades.
Choosing caulk
For tubs and showers, 100 percent silicone sealant labeled for kitchens and baths is the most durable choice. It stays flexible, sheds water and resists mildew. It does not take paint, and new silicone will not stick to old silicone residue, which is why removal matters.
Siliconized acrylic caulk is easier to tool and clean up with water, and it can be painted, but it does not last as long in a wet area. Pick a color that matches the grout or the tub, usually white, bright white or clear.
Laying a clean bead
Fill the tub with water before caulking the tub joint. The weight pulls the tub down slightly, the same way it sits when someone is bathing, so the joint is caulked at its widest and the bead is not stretched later. Leave the water in until the caulk has cured.
Painter's tape on both sides of the joint gives a straight line. Cut the tube nozzle small, push the bead into the joint at a steady pace, smooth it with a wet fingertip or a tooling tool, and pull the tape right away while the caulk is still wet. Most silicones need about 24 hours before showering; check the label.
What caulk will not fix
Caulk seals joints that move. It will not fix loose or hollow tiles, crumbling grout, or a soft spot in the wall. If tile near the tub feels spongy, the board behind it may be wet, and that needs to be opened and looked at.
Grout problems are covered in our regrouting guide, and cracked tiles in repairing broken and chipped tile.
Keeping it clean longer
Squeegee the walls after showering, keep the door or curtain open so the space dries, and run the bathroom fan for 20 minutes after each shower. A mild cleaner once a week keeps soap scum from feeding mildew.
Around the faucet and spout
The joints around the tub spout, the valve trim plate and the shower arm flange matter as much as the tub edge. Water running down the wall finds any gap there and goes straight into the wall cavity. Caulk around the top and sides of trim plates, and leave a small gap at the bottom so any water that gets behind can drain out.
A loose spout that rotates on its pipe should be tightened or reset before you caulk it.
What our visit involves
We recaulk tubs, showers, sinks and toilets. See recaulking.
After recaulking a shower or two, we often stop at Bánh Mì Hòa Phát on North Garfield for a roasted pork sandwich.
Want us to handle it?
Call or text (626) 684-3505, Mon–Sat, 8:30 AM–7 PM. Send a photo and we will give you an upfront quote.
Call or text (626) 684-3505