When and how to use RV roof sealants

By Cheri Sicard
Josh the RV Nerd, one of our readers’ favorite RV experts, is going to teach us all about RV roof sealants in the video below. Josh covers what RV roof sealants are, when to use them, and how to use them.

Unless you have a molded fiberglass RV, chances are you will need this video at some point in your RV journey.

Considering the many different RV roof sealant brands on the market, according to Josh, if you call an RV store and ask what kind of sealant do you need to seal your RV’s roof, you will most often be told, “lap sealant.” But did you know there are two different types of lap sealant?

Josh says they do the same things in different ways, and depending on what you are sealing, one may be preferable over the other. Let’s explore.

Self-leveling lap sealant

Josh compares self-leveling lap sealant to thick pancake batter in that it will ooze out and spread. A dollop the size of a nickel will spread out to the size of a quarter. In other words, it flattens itself out over time and a little of it can go a long way.

Where to use self-leveling lap sealant

Use self-leveling lap sealant around big fixtures on your RV’s roof, for instance, vents and skylights.

When to use self-leveling lap sealant

Josh says to use it for touchups anytime you see little cracks starting to form or any air bubbles in your current RV roof sealants. Watch the video for details.

If, however, you touch the old seal and it leaves a chalky residue, or it starts to crumble, you will need to peel off the old sealant and replace it. Josh discusses how to do this in the video. However, be prepared—it is not easy.

Non-leveling/non-sag sealant

Conversely, this sealant does not spread out later but rather maintains its shape. Be aware—this stuff is not easy to clean up.

Where to use non-sag lap sealant

Use non-sag sealant where you don’t want the excess to drip over, for instance on the roofline and on corners of your RV.

So, this is the material to use along the roofline. See video for details.

That said, Josh says most RVers will be using the self-leveling type of RV roof sealant most often.

[BTW, Josh is now at Bish’s RV.]

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