What changed our mind about stripping the roof was two things:

1. When we cut back the ridge the mess from that coupled with the fact that walking on the roof loosen untold 'trash' we figured we couldn't get the purlins installed without there being mounds of loose shingles laying against them before we were done. Also we would have had to trim off any overhang of shingles on the eaves and gables.

2. Our carpenter friend, each time we talked to him, asked if we were going to strip the roof. There has to be some wisdom there that we are missing, and he never has given us an exact reason, but now with the roof stripped we can work easier and know what 'lays beneath' the roof.

Here I am with a rock climbing harness on roped to the peak of the roof with a shingle stripping shovel removing the previous patch work. Because we are installing the purlins we don't need to remove all the nails, if we were going with asphalt we would need a smooth clean deck. But, the purlins hold the steel up off of the deck and away from the nails.