We have a new inspection article:
“Inspecting the Kitchen Exhaust”](http://www.nachi.org/kitchen-exhaust.htm)
Not sure I agree.
Photo captions at the end of the article say aluminum tape bad- but mastic good, with no further explanation on that subject.
Do not recall seeing mastic being used past commercial stuff on micro hood venting.
Not sure of the issue with that here either…
All kitchen exhaust ducts should be air tight, fastened and sealed, preferably with mastic.
We’ve updated the article to include additional information about mastic. Take another look at the article www.nachi.org/kitchen-exhaust.htm
I still think its not entirely accurate, but I’m not going to debate with Ben Gromicko 
Some nationalities I deal with will not even consider a vent-less hood of any kind because of the heavy wok cooking which produces lots of grease.
My original issue was with the photo showing metal tape as bad however on my big screen see you referring to the unsealed portion which I would agree with.
Installed over 1,000 of those things Micro and hoods so have interest in the article.
No doubt mastic may be better however see no issue with aluminum tape either as it is made for heat.
I used to recommend charcoal filters but they are almost a waste of money as they become costly and do not get changed often as need in many cases.
Condos are where you almost never see them especially in high rises (over 8 stories)
I like it…Down here in Fl. I often find the microwave recirculating exhaust. Somehow the flippers seem this is acceptable. Nice article to pass on to the clients. Thanx