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What sealant to use between bath/shower tray and tiles — keeps cracking after 6 months?
Fed up with this one. I've been using standard white silicone between the shower tray lip and the wall tiles and it keeps cracking at the corners around 4-6 months after install. I've tried a couple of brands. Is it a product issue, a movement issue, or am I making an application mistake? Any recommendations for a product that actually holds?
2 Answers
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Two things I'd check: first, are you leaving a 6mm bead minimum? Thin silicone tears faster under movement. Second — and this is the big one — make sure the tray is fully supported underneath. Any flex in the tray at all will crack the sealant within months no matter what you use. Pack solid with mortar or use a dedicated tray riser kit. Once the substrate is solid I've had Geocel 4200 last 5+ years in busy family bathrooms.
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Cracking at the corners is almost always movement — the tray flexes slightly under load and standard silicone can't keep up. Make sure you're using a sanitary silicone not a general-purpose one. Dow Corning 785 or Sika Sanisil are worth the extra.