soon as this weather breaks , I will be ready to cut out the roof and install the chimmey, I have a metal roof and had to order a rubber boot kit to install this chimmey system the instructions state to use a silcone sealant under the edges of the boot to give it a waterproof seal. my question is would roofing cement or (aka) black jack be better to seal the boot with or silcone? which one would last the longest they sell black jack in tube form to be use in clauking gun.