Twinster- If you check "Fun Finder Solar Install Part 3" on the search, you can see a photo of a completed installation. I did not use butyl tape, although I don't see any reason why you couldn't. Instead, I puddled a small amount of Dicor lap sealant on each of the 8 well nuts just before carefully lowering the panel's four feet onto the roof. I also puddled some sealant on top of each exposed stainless bolt head/washer to prevent top down water penetration. If you want to do the belt and suspenders approach, you might just pool Dicor under and over the entire bracket and onto the surrounding roof skin. My current TT is a different brand. I recently bought it used from someone who had paid the dealership to add two 200 watt panels to the roof. That dealership pooled Dicor over each bracket foot.