Remove the old caulking by digging a plastic scraper or utility knife between the window frame and the actual window.
Go inside the RV, and remove the window by unscrewing it from the frame. Leave enough space to remove the window from the outside.
Step outside the RV and grab the window, pulling it towards you to fully remove it from the frame.
Cut the tip off the tube of caulk according to the diameter of the bead of caulk you'd like to lay. For example, if you'd like to lay a 1/8 bead of caulk, cut the tip of the caulk tube off at the 1/8 inch marking.
Place the caulk nozzle on the top of the window frame. Squeeze the caulk, moving along the top of the window frame, down the right side, along the bottom and up to the original starting point.
Pull the caulk gun or tube towards you at a 45-degree angle, releasing it as you move it away from the frame.
Replace the window from the outside, and screw it back into place from the inside. Double check that the entire window has caulking around it.
Smooth the caulk with your fingers. Be sure there are no gaps in the caulking, which can lead to leaking in the future.
