The rubber actually seals pretty good to the glass without anything. I did one for another member without any sealant to the glass and it did not leak, As said above, I used the windoweld urethane in caulk tube between rubber and glass on mine (added after it was in place). The butyl rope around the outside of seal (in the groove of the rubber) will do great to seal the metal EXCEPT for under the front. Use the liquid butyl there.