Dear Gary,
I sure wish I had the ability to attend more of your workshops. Do most RV manufacturers use butyl tape under the items they attach to the exterior of the RV? Is using multiple 1-inch strips under all of the area of the accessory necessary or can I just go around the edges of, say, a 4″ x 4″ item? —Robert W.
Dear Robert,
Yes, it is the norm for manufacturers to apply a layer of butyl tape (otherwise known as putty tape), or some form of sealant/weather-proofing, between components and the exterior surfaces of the RV during installation. In fact, to prevent leaks, it’s a mandate.
However, it’s only necessary to apply the sealant (personally, I use Eternabond DoubleStick tape) under all the screw locations or around the flanges. You don’t need to place additional strips unless it creates a mounting or balance problem for that device. I’ve never seen that happen, by the way. But just a layer under the flange perimeter of whatever the widget is, where the screws go through, should do the trick. Just be sure there are no voids or gaps between the accessory and the roof or sidewall. Notice how the window in the photo here needs new sealant!
Read more from Gary Bunzer at the RVdoctor.com. See Gary’s videos about RV repair and maintenance.
##RVT802
I’d like to add a little to the discussion on butyl tape. I have an 07 Winnebago Outlook that I have been redoing all the leakable joints on. I have found a product called non-sagging lap sealant that is actually made for roofing, but works extremely well for sealing the gap between the trim and outside fiberglass. It is tricky to work with because it “skins” quickly, but once you get the hang of it, I have found nothing better for sealing up the RV.