Remove the old sealant with a utility knife once the source of the leak is found.
Clean the area with water and soap that doesn't contain petroleum. The best brand to use is Dawn dish washing soap.
Fill the area that was leaking with sealant, using a caulk gun. Keep in mind that the sealant needs to dry flexible so it doesn't crack.
Spread the sealant smoothly with the plastic putty knife. Make sure you fill all gaps and leave a little extra because as it dries it will shrink a little.
Check that the sealant is good around any holes in the roof or around any fasteners or screws. Fill in if you missed these spots.
Allow the sealant dry for at least 24 hours before using the RV.
