Interior
Why your shower caulk failed after two years
Almost always installation, not product. Caulk applied over old caulk cannot bond — and the removal is most of the actual work.
Caulk is the cheapest material in your house and one of the most consequential. In a shower it is the only thing between water and your subfloor, and when it fails it does so quietly — a hairline separation at the base of a tub surround that lets a little water past every single day for two years before anyone notices the floor has gone soft.
When people ask why it failed so fast, the answer is almost never the product. It is how it was applied.
The four reasons it fails
- It was applied over old caulkThe single most common cause. New caulk does not bond to cured caulk, especially silicone — nothing bonds to cured silicone, including more silicone. The new bead sits on top, looks thick and lumpy, and separates within a year.
- The surface was wet, dusty or soapyCaulk needs a clean dry surface to adhere to. A joint wiped down and immediately caulked, or one with soap residue in it, has nothing to grip.
- Wrong product for a moving jointA tub filled with water and a person weighs a great deal more than an empty one, and it moves. A rigid or low-elongation sealant in that joint tears. Wet-area joints need a flexible product rated for it.
- The bead was too thin or tooled awayA bead smoothed down until it is a film has no body to accommodate movement. It needs enough material in the joint to stretch.
Removal is most of the job. Getting the old bead out completely — every trace, including the residue you cannot easily see — is slow, awkward work in a confined space, and it is the entire difference between a repair that lasts eight years and one that fails in eight months. Anyone who quotes a re-caulk as a fifteen-minute job is planning to caulk over what is there.
If it's black and mouldy
Cleaning will not fix it. Once mildew is growing within the caulk it is through the material rather than sitting on top of it, and bleach will lighten the colour without removing the organism. The fix is removal and replacement.
If it comes back quickly after a proper replacement, the problem is not the caulk — it is ventilation. A bathroom exhaust fan that does not actually move air, or one that vents into an attic rather than outside, leaves humidity in the room long enough for mildew to establish. Hold a tissue to the grille with the fan running. If it does not hold, the fan is not doing anything.
One thing that catches people out
Silicone is excellent in wet areas and permanently unpaintable. Nothing sticks to it — not paint, not primer, not more silicone. If a joint might ever need painting, particularly on trim or where tile meets a painted wall, use a paintable product. Getting this wrong means the only fix is complete removal, which in a finished bathroom is genuinely irritating.
How often to check
Twice a year, spring and fall, run a fingernail along the joint at the base of every tub and shower and along the counter-to-backsplash line. If it lifts, separates, or you can see a dark line at the edge, deal with it. It is the highest-consequence five-minute check in the house, and the cost of ignoring it is measured in subfloor rather than sealant.
From our own jobs
Keep reading
Related
Why everything in your house broke the same year
If your home was built between 1998 and 2012, the components didn't fail at random. They were installed together, to a price, with the same service life — and they're expiring on schedule.
A seasonal maintenance calendar for the Piedmont
Humid summers, freeze-thaw winters, red clay and heavy tree cover. What to check and when, written for Iredell, Catawba, Lincoln and Mecklenburg counties specifically.
Next step
Send the list. We'll tell you what's realistic.
Photos, notes, an inspection report, a screenshot of your notes app — whatever you have. We read every one and reply with a straight answer, including the parts we're not the right fit for.