I'm finishing up my coop - thank goodness, cuz the teenagers need to move out now! - and I've run into a couple of problems on the roof. First is that the caulking I got isn't filling in the gaps between the plywood. It's Blacktop and Roof Caulking, so that should be good, right? Not so much - it's as thick as tar and was really hard just to get out of the container. I've applied it twice and I've still got gaps - any suggestions? Second is the flashing, which I've never installed before. I was told that I should use my 3/4" roofing nails to install the flashing, however, those nails won't break through the aluminum. I tried nailing guide holes through the aluminum but they're not big enough for the roofing nails to go through. This may sound stupid, but do I need to pre-drill guide holes in the aluminum? Or should I just use regular nails? Thanks in advance - really appreciate any advice.