Stop water finding its way in through a cracked window seal
The most common cause of window leaks in RVs, campervans, and caravans is deterioration of the window seals due to movement and exposure to the elements.
Captain Tolley’s Creeping Crack Cure uses capillary action to seep into these cracks and seal them from the inside, without needing to remove the window or replace the seal.
“Sealed a ‘delaminated’ caravan window – it was half full of water after torrential rain. After reading tips from caravan club website drained the window with aquarium tank tubing (£1.50 for 2.5 m) through the bung hole, sucked the water to the end of the tube then let it drain out… after letting the remaining condensation dry up over a few days of dry breezy weather I trickled the CTCCC along the side. Gave three applications with 30 mins between each. Had a few more torrential downpours since and the window has held up, in fact it’s never been so clear! I’d noticed it was often misted up in the morning! So pleased I’m 69 y.o. female, the guys wanted to drill holes and get the mastik out… messy!”
– Anne, Judge.me review
“Mystery leak under window treated by applying all round outer seal several times. Seems to have worked as no further leak after several bouts of torrential rain”
– Janet, Judge.me review
“I needed to shore up a leaky area around fitted windows in my campervan. Fantastic product.”
– Michael Manwill, Judge.me review
*For best results, apply in dry conditions above 10°C / 50°F and keep the area dry while it cures. Cold or damp weather slows curing, and moisture can dilute the sealant before it sets, so allow extra time if conditions aren’t ideal. If you’re working in a garage or storage space, check if the air feels dry, not just that it’s out of the weather, and allow extra time to cure if it’s damp or unheated.
This works best on a true hairline crack or gap in the seal – finer than about 0.8mm. If you can see a fine line but can’t fit a fingernail into it, it’s a good match. A window that’s visibly delaminated or has a wider gap between frame and glass may need the seal replacing rather than sealing.
It works most reliably on a fixed seal. On an opening window with a hinge, particularly a vertical or hard-to-reach gap, gravity can work against the sealant before it has a chance to take hold – in a few cases, following up with a small bead of silicone underneath, then a coat of the sealant over the top, has helped where the sealant alone wasn’t quite enough.
Yes, once fully cured – apply it in a dry spell and give it a full day before exposing it to rain, so the sealant has time to set properly.
Riveted aluminium panels, seams and window seals all rely on a thin bead of sealant to keep water out, and that seal shrinks and cracks with age, letting water track in behind the shell.
Rivets and fastenings loosen with age and vibration, leaving tiny gaps that let water creep in - a common issue on riveted trailers like Airstreams.
Caravan and motorhome shower trays are lighter than a home tray and flex with movement and changing temperatures, so hairline cracks in the sealant are common.
Grab handles, roof vents, awning rails, roof lights, and other fittings bolted through the bodywork all rely on a seal around each fixing point to keep water out.
