We put on two complete layers of roofing paper, overlapping by about half. It was cut a little long, which we trimmed later.
This is just a test fitting to determine what it looks like to have the first course doubled, and a five inch exposure.
Fast forward a few courses later, we're running through the end of the bundle of shingles. I developed a strategy of lining up the new course of shingles across the entire width of the roof and paid attention to where the edges (not the ends side to side) lined up. I made sure no two courses had any shingles that had edges that lined up. Once I knew which shingles would be placed in which order, I then used a five inch wide shingle to determine how much of the undershingle to leave exposed, nailed down the first shingle, then slid the measuring board along, squaring up shingles along the way, nailing them down as I went.
Looks nice, doesn't it? By the way, it smells divine. Almost done here.
