On Tue, 10 Dec 2013 12:44:27 -0700, jamesgang
wrote:

...snip...

The common distance is 2 inches I believe. You can't have it contacting
the wood framing. Everywhere I have seen it, it is hung with metal
straps. And flashed around it like yours when it passes through fire
barriers such as a room ceiling.

Thanks, that's about the distance at the minimal spot between the pipe and
across the flashing.