Mould resistant bathroom sealant
Updated: 23 October 2026
The bead around your bath has gone black again, or water is creeping past a joint you sealed last year. A mould-resistant line on the cartridge is only the bead. Condensation still feeds mould if the room stays wet, and a fungicide does not replace an extractor fan. This page is for a UK bath, shower or basin, using GOV.UK damp guidance and the listings in our [sealant comparison](/hub/fillers-adhesives-and-sprays/sealant). A qualifying purchase can earn a commission at no extra cost to you.
The bead around your bath has gone black again, or water is creeping past a joint you sealed last year. A mould-resistant line on the cartridge is only the bead.
The bead around your bath has gone black again, or water is creeping past a joint you sealed last year. A mould-resistant line on the cartridge is only the bead. Condensation still feeds mould if the room stays wet, and a fungicide does not replace an extractor fan. This page is for a UK bath, shower or basin, using GOV.UK damp guidance and the listings in our sealant comparison. A qualifying purchase can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Mould claim | Pack | Stated use | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Sika Sika SikaSeal sanitary silicone, white | Mould resistant | 295 or 310 ml | Bath, shower, window | 9.0 | about £7.69 | View offer |
| Best value |  Sika Sika SikaSeal general purpose silicone, white | Anti-fungal | 260 or 280 ml | Kitchen, bath, PVCu | 9.0 | about £5.00 | View offer |
 ADVANCEDSIL ADVANCEDSIL clear kitchen and bathroom silicone | Mould resistant | 120 ml | Kitchen and bathroom | 8.6 | about £8.99 | View offer |
On this page
Mould on the bead or damp in the room
Black growth on the bead and damp in the wall are different jobs. A fungicide resists growth on the cured rubber. GOV.UK treats condensation from showering, cooking and drying clothes as a common path to mould, and it expects a fan that actually works. Do not brush mould so spores spread, and do not paint over it or smear new silicone on top. If the ceiling below is stained, or the tray has dropped, the water is already past the joint. Once you do need a new bead, the shortlist is on best bathroom silicone sealant.
What to use on a bath or shower
For a flexible wet joint, start with sanitary silicone that names a fungicide: white Sika SikaSeal at about £7.69, item type Everbuild 500, 4.5 from 10,620 reviews. You need a gun, and the title disagrees with a bullet on 295 ml versus 310 ml. The white and clear general-purpose cartridges, about £5.00 and about £6.00, also claim an anti-fungal, and they are still named general purpose. They are the second choice for a full shower reseal. The 151 tube at about £3.35 states waterproof and 24 hours, not mould resistance, so do not make it the shower seal. ADVANCEDSIL’s 120 ml clear tube claims mould resistance and includes a smoother, at about £8.99. It is a patch, with smell complaints in a small room.
When the water is already behind the joint
Hollow tiles, a tray that rocks, or a brown stain on the ceiling mean the path is behind the joint. A new line on the front hides it. Call a plumber, or report it if you rent. A tenant should not open a dropped tray to see where the water goes. Penetrating damp is not settled by anti-mould silicone. A tired bead you are allowed to refresh, in a room with a working fan, is the DIY slice. The Consumer Rights Act 2015 still applies to a cartridge that is not as described, including one past a stated shelf life. It does not cure a leaking ceiling.
Strips, smell, and aftercare
A strip is a weak shower-corner fix. SOL reviewers described ends that lifted within a day and corners that could not be done in one piece. MAGOSIS is 3.8 cm wide and 3.8 from 87 reviews, with adhesive that fails in part of the sample. AILUYA’s 8 mm tape states an 8 mm gap and has three reviews. A mildew word on a title is not a sanitary classification. The format split is on silicone versus a sealant strip. The vinegar smell is the acetoxy cure: ventilate, and keep it off marble. After the cure on your pack, wipe the rim and run the extractor.
Common questions
Will mould-resistant silicone stay white?
Not as a lifetime promise. The additive resists growth on the bead. Condensation, soap scum and still air still feed mould. GOV.UK treats ventilation as the control for condensation damp. A bright white sanitary cartridge can be wiped, which reviewers mention, and it can still go black in a room with no working fan.
Should I use general-purpose silicone on a shower?
Only with the limits on the listing. The white and clear general-purpose cartridges here claim an anti-fungal and name a shower surface. They are not sold under a sanitary name. For a full reseal, the Everbuild 500 sanitary cartridge is the closer match. General purpose is the better fit for uPVC and household gaps, after you check the date.
The bead is black but still stuck. Clean or cut out?
Clean surface mould as the household guidance describes, without dry brushing, and get the fan working. Cut the bead out if it has cracked, peeled, or you are about to rely on it to keep water in the tray. New silicone on top of a failed bead does not bond.
Can a sealant strip replace silicone in the shower corners?
Not as the default. Corners and uneven gaps are where strips in this set fail. A straight, shallow edge is the strip’s limited case. A shower corner that moves wants silicone tooled into a clean dry joint. Tape over a leaking corner hides the leak.
I rent. Is a new bead my repair or the landlord’s?
A surface bead you are allowed to refresh can be yours. A stain on the ceiling, a dropped tray, hollow tiles, or damp inside the wall is a report, not a DIY opening-up.
Why does it smell of vinegar in the bathroom?
Acetoxy silicone releases acetic acid while it cures. The smell is normal and it needs ventilation. It is also the cue to keep that paste off marble, granite and some bare metals. If you cannot tolerate the odour, you need a neutral-cure product, and this comparison does not include one.
What if the ceiling below is stained?
Stop. A new bead will not pull water back out of the ceiling. That stain can mean a failed tray, a leak behind tiles, or a problem in the flat above. Tell a plumber or your landlord, and do not cover the joint until someone has found the path.
Related pages
Sources
Public UK sources used for this comparison. amazon.co.uk prices, stars and review counts are the stored listing snapshot in the digest, not a live scrape. The digest does not give a separate retrieval date.
- Sika Everbuild general-purpose silicone (retrieved 22 October 2026)
- UniBond sanitary silicone sheet (retrieved 22 October 2026)
- UniBond Triple Protection sheet (retrieved 22 October 2026)
- Soudal UK acetoxy and neutral-cure FAQ (retrieved 22 October 2026)
- Soudal UK silicone on natural stone (retrieved 22 October 2026)
- Soudal sealing strip technical data sheet (retrieved 22 October 2026)
- GOV.UK damp and mould (retrieved 22 October 2026)
- GOV.UK construction products (retrieved 22 October 2026)
- BSI EN 15651 series (retrieved 22 October 2026)