11/04/2026
THIS is why your caravan leaks… and you don’t even know it.
J-Mould leaks are one of the MOST common causes of water damage in caravans, and most owners don’t realise until serious damage has already been done.
J-Mould separation happens over time, and here’s why.
Expansion & contraction
Caravans are built with aluminium, which constantly expands and contracts in heat and cold. Over time, this movement breaks down your seals.
Movement on the road
Your caravan is a home on wheels. Every trip creates vibration and flex, and because the bonding surface of a J-Mould is limited, seals begin to crack, peel, and fail, often without you noticing.
Poor preparation (the biggest problem)
You can apply as much silicone as you like… but if the surface isn’t prepared properly, it WILL fail.
At Leak Tight RVs, preparation is everything. We use proper methods like isopropanol alcohol to ensure maximum adhesion and long-term results. Shortcuts and poor prep? That’s where failures start, sometimes within just a couple of years.
This is why a professional leak test is so important.
At Leak Tight RVs, we don’t just find leaks,
We find the ones that haven’t caused damage yet.
Because it’s not about waiting for a major problem…
It’s about preventing one.
Protect your investment before it’s too late.
📲 Book your leak test today
🚐 Leak Tight RVs
Professional. Controlled. Proven.