Butyl tape is typically used between the item (rain gutter end caps) and the unit to seal screw hole, etc. Sealing vertical items (gaps and edges) you'll find silicone (DOW) products. Roof top, flat surfaces use (DICOR) self leveling type lap sealants. The roof should NEVER get silicone products . . . DICOR (with the picture of the bald guy on it) is the best thing for roof. So in answer to your question, it's probably black silicone, or could be butyl squeeze out. Hope this helps?
|