A leaky RV can be a big problem. Wood can warp, mold can grow, and fiberglass can delaminate. The best way to limit this type of damage is by preventing leaks before they happen or catching them fast when they do. Quite often I check on mine during a big rainstorm (by check I mean freak the fuck out). Checking an RV for leaks is a little more involved than it sounds. Water can hide in the corners and leak behind walls. While it can leak in places you will never find, there are plenty of places you can find so be proactive and check it out.
I start checking by feeling around each window. Most RV windows have something called weep holes. Weep holes are used in sliding windows they allow water to drain outside the track and not collect around the track where it could leak into the rv.
Clogged weep holes can be a cause for the windows on your RV to leak. The easiest way to unclog a weep hole is by using a can of compressed air, and a pipe cleaner.
After checking windows I check all the corners, especially in slides. Some slides have furniture that blocks getting to the corner, while it’s a hassle it’s worth taking the top of the bench off your dinette or unfolding your couch to get behind it and check for any dampness.
Another place to look is anywhere there is a fitting for something that runs outside. On our RV we have a 50 amp power cord. It’s quite heavy and the weight pulled the plug assembly forward a little creating space between the gasket and the wall. No matter how much I tried to tighten this I could not stop the leak. I finally had to use some clear silicone to fix the problem. This is a great example and it’s not commonplace to find a leak there, but since I was feeling around the floor during a rainstorm I was able to find it.
I also check the storage compartment doors. In newer designs the compartment doors are constructed in layers. The main door then the trim is glued around it. You’ll notice that the seam around the trim has been sealed by the factory. After a time that seal weakens and it will let water in. If you see drips on the inside by opening the door after a rainstorm or feeling around inside the cabinet that a sign you need to re-seal it. Another sign is if you gently push your fingernail around it and catches or digs in. Generally, these seals need to be re-sealed with clear silicone every 2 to 3 years.
It actually only takes a few minutes to check around the RV and doing a walk-through during a rain storm monthly is totally worth the effort.