with all due respect that detail is reverse lapped,installing it under the flange but over the zip tape sill flashing is still reverse lapped and that my friends can bite you
My window didn't have a zip tape sill pan. If it did, the flashing would have gone on before the zip tape.
Technically though, they want the zip tape sill pan to lap onto the zip wall with no flashing at the bottom flange and nothing to keep water from staying behind the siding.
At which point, the flashing in front of the Zip Tape is nothing more than a window flange extension and has nothing to do with the manufacturers specs on the zip wall. The product is installed as recommended by Zip-Wall.
When the head flange tape gives way and leaks water down to the zip tape pan, the pan will do exactly as it was intended and divert the water back out BEHIND the siding, where Zip-Wall prefers it, apparently.
However, the water that flows over the head tape, down the sides of the window and onto the aluminum flashing will be diverted to where I want it, to daylight.
It's not that it took him an hour to make 100 bucks, it's that it didn't take you 10 hours to save 100 bucks.