Replace the joint now, or will it last another year?

Red, amber, green

Now. Cracks in the mass. The flank has let go of the tile or the tray. Mould inside, not a film that wipes off. Damp in the next room. Do not wait.

Soon. The joint is years old, hard or stiff. It may not drip yet, but the next heat cycle can split it. In a wet zone, a change at 5–7 years is not fussiness: plasticisers leave and the material goes rigid.

You can wait. It only yellows from UV or cleaning, it is still elastic, and a push does not open it anywhere. If the colour bothers you, that is looks, not a leak.

What you cannot see

Everyone looks for a split down the middle (cohesion). The real danger is often adhesion. A “perfect” bead that, when you push, opens a millimetre: water walks in by capillary action and the bead funnels it into the building. No hole on show. Still a leak.

That is why you look and feel.

The thumb test

Clean cloth, raking light, your thumb. Wipe soap: sometimes “filthy” is only filthy. Light along the edge: hairlines and specks in the mass. Push the bead into the joint. If the flank parts, replace. At an end, a careful nail: if it lifts with no fight, the rubber is dead.

What not to do if it is time

Over the old layer: two skins and mould in months. Bleach it white and leave it: the colour goes, the mass stays pitted. Thinking a leak always shows on the ceiling below: by then the plaster has already drunk.

Exceptions

Still unsure after a push: treat it as red. A shower joint is not forever; 5–10 years in a wet room with decent material is a typical range, not a promise. Cheap stuff, often less. Drying, ventilation and no chlorine stretch the life; they do not resurrect a colonised mass.