How To Seal An RV Slide Out To Keep Water Out
It has been a rainy spring in Idaho. We have had several weeks of rain pouring down.
I was sitting working at my desk with my feet on the carpet when I suddenly felt that my feet were wet.
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At first, I thought my wife had spilled something, but when I took a closer look, I felt the water all along the side of my slide out. The carpet was soaked!
It was still raining cats and dogs, but I had to go out and check how the water was getting in, and I quickly found the issue.
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The seal where the slide-out wall meets the floor had cracks in it.
The sealant hadn’t been replaced and reapplied since the trailer was manufactured back in 2013.
This is where the water got in:


With cracks in the sealant, water was able to go in behind the strip and into the screw holes.
Of course, we should have looked at this and noticed the big crack and realized that it would cause issues, but at least we have learned our lesson!
We’re hoping that by posting this, others will check their slides and prevent leaks before they happen.
Resealing the slide-out strip
What we did to fix the leak was to remove the strip. It was about six screws that had to come out. Then we cleaned the strip, the wall and let them both dry off.
Putting it back on is as easy as taking it off, and we did so after putting non-leveling lap sealant (click to view on Amazon) throughout the whole back of the strip and screwing it back on.
We finished it off with sealant on both the top and the bottom of the strip to create a completely watertight seal.
Maintaining a Watertight Seal
Now, to maintain the watertight seal you need to check this seal every month to make sure the sealant hasn’t cracked or fallen off.
Of course, it’s also a good idea to go over your whole trailer and check every seal there is.
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There are a lot of places on your RV where sealant keeps the water out of your RV, and each of these places needs to be maintained and resealed if damaged.
If you have found water leaks in your RV, or have something to add to this post, please leave a comment down below.
I found a puddle of water on my window ledge in the slide out. Then i noticed the carpet really wet under the couch below the window. Not sure what to do?
Hi Marilyn,
It sounds like there may be water coming in through either the window seal or the slide out roof.
First, check the caulk around the outside of the window you found water on. If it has gaps and chips in it you should remove it and recaulk it.
If the window caulk job seemed watertight the problem is probably on the roof or sides of the slide out. You will need to inspect around the areas where there’s caulk to see where the water is getting in and then repair it.
Hopefully, you find the source of the leak. Water inside an RV is never fun and it can take a few tries before finding the exact spot that’s leaking.