Caulking a window

Dicor sealant, the kind for vertical surfaces, not the self leveling kind.

Yep Dicor non sag is what you want for that application.

In construction caulk is NOT the primary means of sealing a window or anything else. Remove the window and replace the butal sealant...reinstall. If you want then use a caulk like the verticle surface dycor or clear polyseal (same as used on the shower door).

I use "tacky Tape" and the name is written on inside of the cardboard roll. Go to a RV store and stick you finger nail into a couple different types. See which one feels best to you. I have a dab of "tacky tape" stuck on top of a fence post (exposed to weather) for many years and it still is pliable. Finger nail mashes right in. I usually buy 1 inch wide as its easy to trim.

I'm hesitant to post, but here goes...most window leaks are from old dried out caulking or poor install. But there are other causes of window leaks as well and HEHR make a lot of different type of windows. Some caulking might come back to bite you in the rear if you ever have to replace the window again because window got broken somehow.

Some questions that you might want to explore before fixing. Do you know for sure if your water leak is the window to the window frame OR the window frame to the window cut out of the RV? Are the weeps hole clear of debris? Have you removed the plastic "ribbon seal" to make sure water can drain to outside and water not build up and leak to inside? Pull a screw at each corner, very much rust on screw? If a lot of rust might be leaking from above the window?

Is the window a slider? Maybe it's not the first time the window has leaked. Make sure someone didn't re-install the slider the wrong way and your getting water because window got turned wrong? That's if slider is horizontal; not vertical.

RV windows are expensive IMO. What ever the cause maybe, I would write down those little tiny numbers and letters you see at one of the corners (think size #1 font; small and hard to see) in case you break the window, you'll be able to get a replacement that is same (radius corners, tint, size, etc)

Some leaks are a bear to find but easy to fix. Hardest one I had was on an older 2003 class C front overhead window. Had the window in and out many times before I finally found the problem. And it was a one piece (non slider) how hard can that be to fix? Lets just say some windows can be a pain. And you do realize that if the leak was caused by just old caulking, it's time to do re-do all the windows. No big deal, just a heads up. First one is the hardest.

And by the way, I do use silicone but just as an "umbrella" for the tacky tape to keep the rain water flowing and draining and not sitting on the window frame every time it rains.

PM me if you want to. I've re-done our windows on about every RV we've owned over the years. It's cheap insurance against water leaks at least windows leaking.

Thanks for the info on the product name - "Dicor Non Sag". Is there a equivalent Home Depot type. Shipping or traveling to a RV store is more expense than the product.

Path1 - Yes, I agree with you best move is to remove and repair. However, I believe I have the location of the leak and if I caulk that location and it stops the leak then I have time to prepare for a removal and replacement/repair of the complete rubber sealing ring.

It appears that the sealing ring slipped slightly out of position during the original installation and left a gap along the top edge.

Regards
MrBHamilton