My Class C has a leak and I see water in the bunk window track. What should I do?

Dear Dave,
I noticed a leak in one of the overhead windows a while ago and caulked the top and sides outside and thought this cured the problem. On our way home the other day, through heavy rain, my wife started getting dripped on. When we got home, I climbed up in the overhead and found that the window tracks were filled with water, and it was dripping down onto the sill and down the wall. On the bottom of the outside of the window are 4 slits. Are these drains, and is there a way to clear these out? Do I need to remove the window and reseal it to the body? Or do I need to replace the window? —Steven, 2019 Sunseeker 3010

Dear Steven,
Your Sunseeker is a Class C, and the photo you provided is the overhead bunk window on the passenger side. The four slots on the bottom of the frame are weep holes and are designed to allow water to escape from outside points and not let water inside the unit.

The window is a two-piece design with the outer window and frame mounting into the cutout opening with a butyl tape (putty) between the frame and the sidewall and an interior frame that securing the window by sandwiching it to the sidewall. The butyl tape should be sufficient to seal the entire window frame so I would believe you have a leak somewhere else that is migrating to the passenger side. Some manufacturers also run a bead of silicone on the top side of the window frame called a cap seal. However, if the butyl tape is applied correctly, this is not necessary.

Clean the drain slots in the window frame

First, I would make sure the drain slots are clean and not clogged with dirt and dust. You can do this with a flat head screwdriver or air compressor. The window is easy to remove and reseal. That might be a good idea as it will allow you to visually inspect the opening and might be able to see the path the moisture is taking. Have someone outside holding the window or use painters’ tape around the edge to the sidewall to keep the outer window and frame from falling out. Remove the inside frame by taking out the screws and pulling off the frame. You might have to cut some of the butyl tape outside or silicone, if it was cap sealed.

You can then remove the window from the outside and clean off all the butyl tape and additional silicone or sealant. Check around the edges of the opening to see if there are any signs of moisture penetration. Before reinstalling the window, I like to apply a layer of rubberized moisture sealant similar to what you would coat a basement foundation with. Just brush on a coat thick enough to get into all the nooks and crannies of the block foam, then apply new butyl tape around the edge of the outer frame and reinstall the inside frame. You may need to trim some of the butyl tape off that gets squished outside the frame.

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Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

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