When to recaulk
- Black or pink mold that does not clean off. It is growing under or inside the caulk.
- Caulk that is cracked, peeling, shrunk away from one side, or missing.
- Gaps where the tub meets the wall or the shower pan meets the tile.
Caulk at wet joints is a maintenance item. Checking it once a year and recaulking every few years keeps water out of the wall behind it.
Silicone or latex?
Use 100% silicone labeled for kitchen and bath, with a mildew-resistant additive, for joints that get wet. It stays flexible and waterproof for years. It cannot be painted, and new silicone does not stick to old silicone. Siliconized acrylic ("latex") caulk is easier to tool and clean up, and paintable, but it does not last as long in a shower.
How to recaulk, step by step
- Remove all the old caulk with a plastic scraper or a razor blade held flat, using a caulk remover to soften stubborn silicone.
- Clean off soap scum and residue. Kill any mold with a bathroom mold cleaner, then rinse.
- Let the joint dry completely, ideally 24 hours with the fan running or a window open. Caulk over damp joints traps moisture and mold.
- For a tub, fill it with water before caulking. The weight lowers the tub slightly, so the caulk does not tear the first time it is filled.
- Run painter's tape along both sides of the joint, cut the caulk nozzle small, and apply one continuous bead.
- Smooth the bead with a caulk tool or a wet fingertip, and pull the tape off right away, before the caulk skins over.
- Let it cure as the label says, usually 24 hours, before using the shower.
What caulk cannot fix
Caulk seals joints; it does not stop water that is already getting behind the tile. Loose tiles, crumbling grout, soft or spongy walls, or stains on the ceiling below mean the leak is elsewhere. Grout lines on flat tile get grout, not caulk; caulk goes at corners and where tile meets the tub or pan. If water has soaked the wall, see bulging or water-damaged drywall.
What it costs to hire out
| Job | Typical cost |
|---|---|
| DIY materials Silicone, remover, scraper, tape | About $15–$40 |
| Professional tub or shower recaulk | $105–$290 |
| Full tub surround | $200–$350 |
| By length A tub surround has about 30–40 feet of joints | $5–$10 / linear ft |
Recaulking is quick, so it is best bundled with other small jobs in the same visit, or included in a seasonal home maintenance visit.
Common questions
Can you caulk over old caulk?
No. New caulk does not bond to old silicone, and any mold underneath keeps growing. Remove it completely first.
How long before I can use the shower?
Most silicone needs about 24 hours to cure; check the label. Some fast-cure products allow water sooner.
Why does mold come back so fast under new caulk?
Usually because old caulk or mold was left behind, or the joint was not fully dry. Complete removal, cleaning and a full day of drying stop it.
Related guides
Compiled from published 2026 national cost data (Angi, HomeAdvisor). DIY costs are typical retail prices. We update these figures as we complete jobs.