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Bathroom Sealant Check
Choose where the sealant is and what you can see, and find out whether to clean it, reseal it, or have a professional look first.
See if it needs resealing
Answer a few questions about the sealant around your bath, basin or shower to see whether to clean it, reseal it, or call a professional first. It does not diagnose mold or leaks. Nothing you choose is saved or sent.
Example
If the sealant around a bathtub is cracked and has a dark stain that goes through it, and cleaning did not remove it, the tool says resealing is recommended, with the steps for taking out the old sealant and applying new. Press “Load an example” to try it.
How it works
The tool first looks for signs that water has spread beyond the sealant or that mold is widespread, which call for a professional. Then it looks for cracks, lifted gaps, deep stains or stains that come back, which point to resealing. Surface spots that wipe off just need cleaning.
Resealing means cutting out all the old sealant, cleaning and drying the joint, and applying a sanitary sealant. Never seal over mold. How old the sealant is does not change the result, because no official standard for it was found.
Frequently asked questions
Can I just put new sealant over the old?
No. The old sealant has to be cut out completely, and the joint cleaned and dried, before new sealant goes on. Sealing over mold or old sealant does not hold.
When should I call a professional?
When water has spread beyond the sealant, such as stains on the ceiling below or the door frame, or when mold covers more than about 0.9 square metres (10 square feet).
Is bleach the way to clean the mold?
Detergent and water are usually enough on hard surfaces. If you do use bleach, ventilate well and never mix it with ammonia or acidic cleaners.
More tools
Sources and last updated
- Based on US EPA guidance on mold and moisture and Sika’s guide to sealing around a basin and bath, both checked 2026-10-22. The result rules are this site’s own, not an official standard.
- What you enter stays in your browser and is not sent anywhere.
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