Supporting Class A through a metal roof

[Ohlen Corbett]

I'm installing ~15 feet of 6" SuperVent. I want to support it from the roof. It is a metal roof. The manufacturer's instructions are sparse. If I understand the chain of events properly, I:

1. Build and install a support frame 10" wide and long enough so that there is a vertical space of 10" when installed, centered over the desired location.
   1. The rubber boot instructions say that the lower support should be parallel to the shield, why is that?
2. Cut an oblong hole in the roof for the pipe to pass through.
3. Place the chimney in the hole at the correct height.
4. Attach the roof support to the chimney.
5. Check for plumb and attach the roof support to the support frame.
6. Assemble the boot flashing/shield and notch around the roof support.
7. Nail the shield to the support frame.
8. Cut and slide on the boot
9. Apply silicone to the underside of the boot and install in a diamond pattern.
10. Install the mesh screen
11. Assemble, install, and seal the storm collar.

Are there any important steps I have missed? Any common mistakes I need to avoid?

Here is my proposed framing:

 

[Holiday]

I can't help much as far as the support part is concerned. The only input I have is I used a metal flashing from excel instead of the rubber which works very well for the metal roof.

 

[Ohlen Corbett]

I thought about using that one, but I didn't think it would work with my Supervent pipe. I was also thinking that a compressed silicone seal would seal better than the silicone at the edges of the cut. I also worried that I would mess up the cut and have to try and seal a gash in the roof.