I live in a mobile home where the previous owner put a unfinished addition on that i use as a work shop and storage.. Both roofs are metal roofing but the addition is 6" lower than the main roof. The previous owner used some old printing press aluminum by the looks of it to create a joint between the 2. Iv been fighting it for years as water runs through the seams and under the metal roofing for the shed. I finally got it to stop after using a bucket of roofing tar but i know that's only a temp fix. I have not been able to figure out how to make a reliable transition between the roof's, the other issue being the addition is about 6" away from the mobile home so now i have to make a reliable connection 6" up but 6" across.. I was going to replace the roof this year and extend it so it was up against the home but never made it that far and now that i found the leak id rather not spend the money on a new roof if i can come up with a better way to fix