DIY GUIDE · HOME REPAIRS & HANDYMAN · CHECKED OCTOBER 2026
How to reseal a bath, shower or sink yourself
An hour, then a day before you use it. £20–£40 in sealant, remover and tools.
Strip it all, dry it fully, fill the bath, then one steady bead tooled once — and where a leak means pipework, not sealant.
- Every step, start to finish
- Checked October 2026 — sources at the end
- Honest about when to call a pro
FIRST, THE HONEST ANSWER
Do it yourself, or get a handymen?
Do it yourself if…
- The old bead is black with mould, peeling, split or shrunk away from the tiles
- The bath, tray or basin is firmly fixed and does not move when you stand in it or lean on it
- The tiles and the wall above the joint are sound
- Water on the floor appears only when the joint itself is soaked
Get a pro if…
- The bath or tray flexes or rocks — it needs supporting or refixing first, and a bead will keep tearing
- Water appears below with the joint dry — the waste, trap or supply is leaking
- The ceiling below is stained, or the floor around the bath is soft
- The tray is cracked, or the wall behind the tiles is soft
Safety first
- Ventilate the room while you strip and seal. Removers contain solvents, and acetoxy silicones give off an acidic vapour as they cure; HSE's COSHH guidance starts from reading the product label and safety data sheet.
- Wear gloves when using remover and mould sprays, and safety glasses when scraping above head height.
- Use a sharp knife held flat and cut away from yourself; a blunt blade slips.
- Do not stand on the bath edge to reach high joints; use a step-ladder on a dry floor.
- If water has reached the ceiling below or a light fitting, turn that circuit off at the consumer unit and get the leak looked at before anything else.
Stop here: The pipework behind the bath, and anything leaking under it
A sealant bead seals a joint, not a pipe. A leaking waste, trap, overflow or supply means working on the plumbing, and work on the supply side must meet the Water Supply (Water Fittings) Regulations in England and Wales, the Scottish Water Byelaws in Scotland and the Northern Ireland water fittings regulations. A hidden leak also risks rot in the joists and water reaching the wiring below. Turn the water off if you need to, and call a plumber. How to hire a sealant applicator →
| MATERIAL | COVERAGE | FOR THIS JOB |
|---|---|---|
| Sanitary silicone sealant | Joint widths and cure rate on its data sheet | One cartridge for a bath or shower |
| Silicone sealant remover | Gel or liquid | One tube |
| Backer rod or expanding filler | For joints deeper than half their width | Only for a wide gap |
How long before you can use it
Cure time ≈ bead depth ÷ the cure rate on the data sheet. A bead about 6 mm deep, in a silicone curing at 3 mm per 24 hours, takes about 2 days to cure right through; at 2 mm per 24 hours it takes about 3 days. Skin time comes first, but a skinned bead is still soft underneath.
Cure rates are measured at room temperature; a cold bathroom slows them. Wait at least the time the cartridge gives before the first shower.
Around a bath, shower or basin, use a sanitary silicone with a fungicide. It stays flexible, waterproof and resists mould. Decorators' acrylic caulk is paintable and fine for gaps round skirting and architrave, but it is not made to sit in water and fails within months around a bath.
The maker's product data sheet gives the figures that matter. One premium sanitary silicone skins in 10 minutes at 20°C and cures at 3mm per 24 hours, with joints from 5mm to 25mm wide; a shower silicone from the same maker skins in 15 minutes and cures at 2mm per 24 hours, and can be applied between +5°C and +40°C. A thick bead takes days to cure through.
A sealant joint should bond to the two faces it bridges and nothing else. The same data sheets say the depth should be no more than half the joint's width. A deep gap behind a bath gets a backing — a foam backer rod or an expanding filler — before the bead goes on, so the silicone is the right thickness.
Most sanitary silicones cannot be painted; one data sheet says plainly that any painting should be done before the sealant goes on. Finish the decorating, let it dry, then seal.
White, clear and a few colours. Clear shows mould and dirt behind it; white hides it until it goes grey. A standard cartridge runs several linear metres of a medium bead — one maker gives 7 linear metres of a 9 × 9 mm joint for one product and 10 for another — so one cartridge does a bath, with some to spare.
THE PART THAT DECIDES THE FINISH
Preparing the joint — by what you are sealing
Find your joint below. Every case finishes the same way: all the old sealant out, the joint clean and completely dry.
An old silicone bead, black or peeling
The usual case.
- Cut along both edges of the old bead with a sharp knife, held flat to the surface
- Pull the bead out in strips, then scrape off the remains with a plastic scraper
- Apply silicone remover to the residue, leave it for the time on the pack, and scrape and wipe
- Clean the joint with methylated spirit and let it dry overnight
Acrylic caulk used round a bath
A bead that has cracked and gone soft and grey.
- Scrape it out completely; caulk softens in water and comes away
- Wash the joint to remove the residue
- Let it dry fully
- Reseal with a sanitary silicone, not caulk
Mould in the joint and on the tiles
Black spots that grow back.
- Remove the old bead first; mould lives behind it
- Treat the joint and the tiles nearby with a mould remover and rinse well
- Let it dry completely before sealing; mould grows back through a bead laid on damp
- Improve the ventilation, or the new bead will go black too
A bath that flexes
The bath moves when you stand in it.
- Check the bath's feet and cradle are tight and on the floor
- Check the wall battens or brackets the rim sits on
- Fix the movement before sealing; a bead cannot hold a moving bath
- If the bath cannot be made firm, stop here
Tiles that are loose or grout that is missing
Water getting in above the joint.
- Press the tiles along the bath; refix any that move
- Regrout missing grout before sealing
- Let grout cure fully before the bead goes on
- Check for soft board behind loose tiles
A shower tray or wet-room floor
Low trays and the joints that take most water.
- Check the tray for cracks, especially at the corners and round the waste
- Run water down the joint, not into it, to see whether water comes out below
- Let the area dry for a day or two before sealing
- Seal the tray-to-wall joint and the screen frame, but never the inside drainage slots of a screen
THE JOB
How to reseal a bath, shower or sink, in order
Strip the old bead
20 minCut along both edges of the old bead with a sharp utility knife, held almost flat to the bath and then to the tiles, so you slice the bead off its bond without scratching anything. Pull it out in strips. Scrape the remains off with a plastic scraper. Read the case above that matches your joint.
- Change the blade often; a sharp blade cuts, a blunt one tears
- Work along the joint, never across it towards the bath
- Put the strips straight in a bag; silicone sticks to everything
Mistake to avoid: Leaving thin traces of the old silicone in the joint. New silicone does not stick to old, and the bead lifts at those spots.
Soften and remove the residue
30 minApply silicone remover to every bit of residue along the joint and leave it for the time on the pack. Scrape the softened film off with the plastic scraper, then wipe the joint clean. Repeat until the surfaces feel clean and squeak under a finger. Treat any mould with a mould remover now and rinse it off.
- Wear gloves; removers are solvents
- Ventilate the room while you work
- Check with a fingertip, not just your eyes
Mistake to avoid: Skipping the remover because the joint looks clean. A film you cannot see stops the new bead bonding.
Clean and dry completely
20 minWipe the joint with methylated spirit or the remover maker's cleaner on a lint-free cloth to remove grease and soap. Then let it dry: overnight, with a window open and the heating on, is not too long. The sealant data sheets ask for surfaces that are clean, dry and dust free. A joint that is damp deep down will not hold the bead.
- Do not use the bath or shower until you have sealed
- A hairdryer on a low setting helps the last of the damp in a cold room
- Check the joint is dry at the bottom, not just at the surface
Mistake to avoid: Sealing a joint that is still damp. The bead looks fine and peels away in strips within a few weeks.
Fill the bath with water
10 minPut the plug in and fill the bath with cold water almost to the overflow. The weight pulls the bath down to where it sits in use and opens the joint to its widest. Seal it in that position and the bead is compressed, not torn, when the bath is used. For a shower tray, stand in it while a helper seals, or load it with heavy buckets of water.
- Leave the water in until the bead has cured, or at least overnight
- A basin needs no filling, but check it is firmly fixed
- Put a towel over the water to stop it splashing the joint
Mistake to avoid: Sealing an empty bath. The first time someone sits in it, the bath drops and the new bead tears along its length.
Mask both sides of the joint
15 minRun a line of low-tack masking tape along the tiles, just above the joint, and another along the bath, just below it, leaving a gap the width you want the bead. Press the tape edges down firmly. The tape gives two clean, straight edges and takes the mess with it when you pull it off.
- Keep the gap even all the way along
- At corners, overlap the tapes neatly
- Do not leave too wide a gap; a wide, thin bead is weak
Mistake to avoid: Masking with ordinary household tape. It leaves adhesive behind, and the silicone will not bond where it has been.
Cut the nozzle and lay the bead
15 minScrew the nozzle on and cut it at an angle, a little smaller than the gap. Hold the gun at a steady angle and push the bead along the joint ahead of the nozzle, at an even speed and with even pressure, filling the joint in one continuous run from corner to corner. The data sheet for one sanitary silicone asks for even trigger pressure and a constant gun angle for the best results.
- Start in a corner and work out to the end
- Push rather than pull the gun; pushing forces silicone into the joint
- Release the trigger pressure at the end of each run, or it keeps oozing
Mistake to avoid: Stopping and starting along a run. Every restart leaves a lump that shows under the finishing tool.
Tool the bead and pull the tape
10 minWithin the skin time on the data sheet — 10 to 15 minutes for the two silicones above — wet the finishing tool with a little soapy water and draw it along the bead in one smooth pass, pressing it into the joint and shaping it. Wipe the excess off the tool as you go. Then pull the tape straight away, while the silicone is wet, peeling it back on itself at a low angle and away from the bead.
- One pass is better than several
- Pull the tape before the skin forms, or you tear the bead
- Have a bag ready for the sticky tape
Mistake to avoid: Tooling the bead after it has started to skin. It drags and wrinkles, and the surface never looks smooth.
Leave it alone to cure
24 hrLeave the bath full, the room ventilated and the bead untouched. Silicone skins in minutes but cures slowly from the outside in — 2–3mm a day for these products at room temperature — so a medium bead needs a day or more, and longer in a cold room. Do not shower, splash or clean the joint until it has cured for the time on the cartridge. Then let the bath water out.
- Keep the extractor fan running
- Do not touch it to check; a fingerprint stays forever
- Mark the date on the cartridge and keep the rest, capped, for small repairs
Mistake to avoid: Showering the same evening. Water on an uncured bead leaves it soft, cloudy and weakly bonded.
The mistakes that make a bead fail
- Sealing over old silicone
- Sealing a damp joint
- Sealing the bath empty
- Using acrylic caulk round a bath
- Using the shower before the bead has cured
Stop here and get a plumber or a bathroom fitter
- Water comes from the waste, the trap, the overflow or the taps, not the joint
- The bath or tray moves and cannot be made firm
- The ceiling below is stained or the floor round the bath is soft
- The tray is cracked or the tiles and board behind are failing
| WHAT YOU SEE | WHY, AND THE FIX |
|---|---|
| New silicone peeling off the bath | Old silicone or soap left in the joint, or the joint was damp. Strip it, clean with remover and spirit, dry overnight and reseal. |
| Silicone bead split when the bath was used | Sealed with the bath empty, or the bath moves. Strip it, check the bath is firm, fill it with water and reseal. |
| Black mould back in a few weeks | Mould left behind the bead, or poor ventilation. Strip, treat with mould remover, dry fully, and run the fan after every bath. |
| Lumpy or wavy silicone | Stop-start application or tooling after the skin formed. Cut it out and reseal in one run, tooling straight away. |
| Silicone still tacky days later | Out-of-date sealant, a very deep bead, or a cold room. Warm the room; if it still will not cure, strip and reseal with fresh sealant. |
| Water on the floor with the bead intact | The leak is not the joint. Check the waste, the trap and the supply connections; if they are not accessible, stop and call a plumber. |
| Gap too big to seal | The joint is wider than the sealant allows. Fit a backer rod or expanding filler first, so the bead is no deeper than half its width. |
| Silicone smeared on the tiles | Wipe fresh silicone with a dry cloth, then a cloth with white spirit. Cured smears need a remover and a plastic scraper. |
| Bead shrank away from the tiles at one end | The joint was wider there and the bead too thin, or it moved while curing. Cut out that length, fit a backer in the wide part, and reseal it in one run overlapping the sound bead slightly. |
| Silicone went yellow or pink | Soap, shampoo dyes or a bacterial film on the surface. Clean it with a mild bathroom cleaner; if the stain is in the silicone, strip and reseal with a fungicidal sanitary grade. |
WHAT YOU SAVE
What it costs to do it yourself
| Sanitary silicone, 300 ml | £4–£10 |
|---|---|
| Silicone sealant remover | £8–£10 |
| Cartridge gun | £6–£8 |
| Finishing tool kit | £4–£9 |
| Total, a bath or shower | £20–£40 |
| DIY total | £20–£40 |
Guide prices compiled by the Locufy team from published Irish and UK provider price lists and 2026/27 cost guides. Updated 2026.
Materials are cheap and the job is short; the cost of doing it badly is a ceiling below. A fitter's price buys the stripping and the judgement on movement.
RATHER NOT?
Sealant applicators near you, with prices shown
The ones who cover your area, nearest first, with one score from every review. No account needed to look.
Or post the job free and let them come to you.
Wait the time on the cartridge before the first bath or shower, longer in a cold room.
Wipe the bead after showering and run the fan. Clean with a mild cleaner; bleach-based sprays age silicone quickly.
Old silicone strips, tape and empty cartridges go in the general waste. Part-used remover and solvent-soaked cloths are better taken to the household waste recycling centre or your council's hazardous waste service. Never pour solvents down the sink.
Leave a little silicone in the nozzle as a plug, or fit a cap, and store the cartridge somewhere cool.
Resealing a bath, shower or sink: questions people ask
Until the bead has cured through. One sanitary silicone cures at 3mm per 24 hours and a shower silicone at 2mm, so a medium bead needs at least a day, and longer in a cold room.
No. New silicone does not bond to old. Strip it all, remove the residue, clean and dry the joint, then seal.
The weight of the water lowers the bath to where it sits in use. Sealed like that, the bead is compressed rather than torn when someone gets in.
Sanitary silicone with a fungicide. Decorators' caulk is for dry gaps you will paint, not for joints that sit in water.
The leak may be from the waste, trap, overflow or taps. If water appears with the joint dry, it is a plumbing leak, not a sealant one.
On the Locufy UK price guide resealing costs £80–£180 per job, typically £115. A shower enclosure with several joints sits towards the top.
MORE GUIDES
More DIY guides
Sources — checked October 2026
- Everbuild Everflex 500 Bath & Sanitary Silicone, product data sheet: 3mm per 24 hours, skin 10 minutes at 20°C, joints 5–25mm, depth 50% of width
- Everbuild Showerproof Bathroom Silicone, product data sheet: 2mm per 24 hours, skin 15 minutes, +5°C to +40°C, not overpaintable
- HSE — COSHH basics: labels and safety data sheets
- HSE — types of ladder and using them safely
- GOV.UK — find a local hazardous waste disposal service
- GOV.UK — dispose of household waste
- Wickes — silicone sealant, price check October 2026
- Wickes — sealant removers, price check October 2026
- Wickes — sealant guns and finishing tools, price check October 2026