Microwave venting - expert opinions needed, other opinions welcome

[Nava]

@Alessan

I’m with Nava - I have a hard time visualizing the situation. How high is the microwave above the stove?

If I’m understanding it correctly it’s a microwave-hood combo. So what actually needs venting is neither the stove nor the microwave: it’s the hood.

[Ann_Hedonia]

@Dag_Otto

Although the building exhaust system you describe doesn’t actually have ducts but uses spaces between walls and ceilings, I still consider this a code violation. Rather than ducts, what the building exhaust system uses is what is technically called a plenum, and no fire inspector would allow a kitchen hood exhaust into such a plenum.

I will certainly look into this. It is also possible that I misunderstood what they did.