I sent this to John Carroll (author of the top-down roofing article), but it looks like he hasn’t posted on BT in a while so I thought I would throw this out to everyone:
“I was intringued by your top down roofing idea and tried it on my shed as a test before doing on my whole house. I loved it! I have always distrusted metal roof jacks, and much preferred the solid scaffold you designed. I am having some issues trying to work out the logistics of doing the top down method on my house, and thought you might be able to help.
My issue is step flashing when the roof meets a wall or a skylight. My house is a series of 3 stacked gables, so I have some long walls that need to be step flashed and sided. I nailed the step flashing on one of them yesterday with shingle scraps as spacers, with the intent of doing the siding from your homemade roof jacks, then doing a conventional roof job from the bottom up (sliding the shingles into the gaps under the step flashing, and dealing with skylights, vents, etc. as I get to them). I had written off the top down method a while ago as incompatible with step flashing, but decided I should ask you.
It seems that nailing the last shingle of a lower section under the first shingle of a higher section would be difficult because one side of the top shingle is held down by the step flashing. Maybe you don’t need a nail on that side because the step flashing is holding it down, so it isn’t an issue…
Have you done this? Does it work out?”