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How to Re-Caulk a Tub or Shower So It Lasts
A tired bead of sealant lets water behind tiles and into the subfloor. Re-caulking takes an afternoon and most of it is preparation.
Marcus Ibe · Sep 16, 2026 · 4 min read · 5 steps
Mould-stained, cracked, or peeling sealant around a bath or shower is more than cosmetic. Every gap lets a little water behind the tile edge on every shower, and over months that can soften plasterboard and rot the floor beneath.
The good news: re-caulking is one of the most forgiving DIY jobs, as long as you remove the old sealant completely and let the new bead cure.
Remove every trace of the old sealant
New sealant will not bond to old sealant, soap scum, or mould. Cut along both edges of the old bead with a sharp utility knife or a plastic caulk-removal tool, then pull it away in strips.
- Use a silicone remover gel for stubborn residue, following the label's dwell time
- Scrub the joint with a mould cleaner if black spots remain, then rinse
- Wipe the joint with isopropyl alcohol to remove grease
- Let the area dry fully, ideally overnight with the fan running
Pick the right product
For wet areas, choose a 100 percent silicone sanitary sealant labelled for kitchens and bathrooms; it stays flexible and resists mould. Acrylic caulk is easier to tool and paint, but it is better suited to dry joints such as skirting boards.
Fill the tub first
Baths flex when filled. Fill the tub with water before sealing so the joint opens to its widest point; once the sealant cures and you drain the bath, the bead is under slight compression rather than being stretched.
Apply and tool the bead
Run masking tape along both sides of the joint, leaving a gap the width of the bead you want. Cut the nozzle small, keep steady pressure, and push the bead into the joint rather than dragging it. Smooth with a wet finger or a profiling tool, then pull the tape away immediately at a low angle.
Let it cure
Most silicone is touch-dry within an hour but needs about 24 hours before it gets wet. Leave the bath full until then if you can.
This is general home-maintenance information, not professional advice. Building codes, permits, and safe practices vary by location — consult a licensed contractor, electrician, or plumber for work beyond your experience.