Google ďRV sealantĒ and youíll find what you need. Generally, use self leveling lap sealant on roofs (Dicor is a leading brand name but there are others). On windows and sidewalls you can use a similar product but NOT self leveling so it wonít run. You also can use polyurethane sealant from big box stores on the sidewalls. This is really good stuff though itís not especially easy to do neatly as itís super sticky. General rule is not to use silicone on anything in an RV. Good for you being proactive on your sealing. Water is relentless and evil in our machines.