I am covering my 10ft 2inch high garden shed in vinyl. The outside corner channels I have are 10 feet long. In order to span the entire height, is there a particular way of joining two corner pieces besides using a butt joint? I noticed on my 25 year old home the corners were joined with pop rivets and an spline apparently. Its a south facing wall and will get hot. The pieces to join would be a 8 foot piece and a 2 foot plus piece.

Thanks