Many older vans end up with leaking windows. This can be due to the installation of the window, or the window fitting itself. Sometimes, it is indirectly caused by a leak from another area of the van like a sheet join or a corner mould. Leaks tend to take a long time to become visible inside a van – by which time there can be considerable damage already caused to the framing and interior plys.
Simply re-sealing around a window is not always a great solution to fix a leak. Neither is using sealants around a window from inside the van. This is unfortunately something we see quite a bit of – it prevents water from dripping down the interior wall, which may seem like it has fixed the problem – but generally just means that the water is forced further inside the wall of your van, causing damage you are unable to see.
A proper fix is to fully remove the window, diagnose extent of damage to the interior frame, and refit the window properly, using a double sealant method.