[Papa]

Originally Posted by Thefireguy

Microwaves are generally not vented
Im not familiar with the layout of your kitchen but the important issues on this type addition include...
1) Make sure the fan for your vent is rated to overcome the friction losses in the duct length
2) Grease laden exhaust fumes must be sealed at all joints in the duct to prevent grease deposits from dripping into the attic
3) If the duct is terminated above the roof some grease stains may be visible on light roof shingles
4) Never allow anyone to install an open discharge into the attic due to the obvious fire consequences
This is work for an accomplished HVAC guy unless you are really good at understanding building and fire codes.

Thanks for the insight