Nashua 557 Duct Tape - How does it hold up??

This weekend I'm going to spend some time in my crawl space tuning up my duct system (flex duct). By tuning up I plan to ensure runs are adequately supported and well connected to junction boxes. I also plan to check for any leaks and repair as necessary. I also want to insulate the plenum from my downdraft AH that goes from garage into crawlspace.
I see that Nashua has a duct tape that's code approved for flex duct called 557. How does it hold up over time? I am generally not a fan of duct tape for ducts but will this stuff actually work?? I also bought some king size tie wraps to reinforce joint connections.
Also what's the best insulation for T junction boxes and plenums. I see rolls of 12" self adhesive insulation but R value is only 3 or so. Would a couple cans of Great Stuff be better at encasing metal connectors with insulation?
P.S. Unfortunately I've had previous problems with flex duct seperations due to a lazy contractor who failed to use good tape, failed to use tie wraps, and failed to adequtely support the flex runs.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@gmail.com wrote:

cloth backed duct tape such as yours is outlawed in California. For good reason. Ammend that. you can use it as long as you also apply mastic to each point of connection as well AND install draw bands.
wrap all exposed metal with 1.5" FSK, secure with FSK Tape, and 18ga galv tie wire 12" on centers.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Most of duct tape in plain language stinks
However there is tape made by TYCO that
does hold and stays, but to save my sole
I am unable to get P/N from them
Dido
wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The only stuff approved in Ca is Venture Tape 1599B
http://www.venturetape.com/final/vt1599.pdf
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thank You Gofish
Dido
wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.