Residential Exhaust Codes and Best Practices

Licensed mechanical engineer Tony Amadio joins the podcast to talk about residential exhaust codes and best practices. He also put together a presentation about the topic, which you can view at

When choosing duct materials for residential exhaust, you will want to stick to sheet metal and mind the gauge; flex ductwork can easily be damaged and will rack up a high total equivalent length in a way that sheet metal will not.

Exhaust air should always discharge outdoors, not into an attic or crawl space, and that air needs to be replaced by air entering the conditioned space; makeup air is the air we draw in to replace the exhausted air, and we need appropriate undercuts to make sure we're getting the right amount of makeup air.

Domestic cooking exhaust may also come in a few different varieties, each of which has different code requirements (with downdrafts needing much more CFM per ASHRAE). Range hood shape is also important for capturing as many particles as possible, but makeup air kits are usually unnecessary (and could be more of a hassle than they're worth).

When it comes to bathroom exhaust, the CFM requirements differ between residential and light commercial, as well as intermittent and continuous exhaust. Steam generators may also be present, and they require extra consideration.

Tony and Bryan also cover:

  • Tony's education and career background
  • Discharging and terminating exhaust air
  • Insect screens
  • Makeup air in light commercial applications
  • Clothing dryer vs. bathroom vents
  • Ductless clothes dryers and condensate piping
  • Home Ventilation Institute (HVI) guidelines
  • Pressure imbalance in a structure
  • Residential vs. light commercial bathroom exhaust
  • Static pressure, blower sizing, and exhaust duct sizing

You can ask Tony questions by email at

Learn more about the 5th Annual HVACR Training Symposium at

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